vvEPA
           United States
           Environmental Protection
           Agency
             Office of Research and
             Development
             Washington DC 20460
         EPA/600/4-91/010
         June 1991
Methods for the
Determination of
Metals in Environmental
Samples
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                                        10|ig/L
               ICP-AES    ICP-MS     GF-AA   1C
               COLD  VAPOR    HPLC-ECD     GC-ECD
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                                             EPA-600/4-91-010
                                                    June 1991
       METHODS FOR THE DETERMINATION

                 OF METALS

          IN  ENVIRONMENTAL SAMPLES
ENVIRONMENTAL MONITORING SYSTEMS  LABORATORY
     OFFICE OF RESEARCH AND DEVELOPMENT
   U.S.  ENVIRONMENTAL PROTECTION AGENCY
          CINCINNATI, OHIO  45268
                                            Printed on Recycled Paper

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                                  DISCLAIMER

     This manual has been reviewed by the Environmental Monitoring Systems
Laboratory - Cincinnati, U.S. Environmental Protection Agency, and approved
for publication.  Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.

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                                   FOREWORD


      Environmental measurements  are required to determine the quality of
ambient waters and the character of waste  effluents.  The Environmental
Monitoring Systems Laboratory -  Cincinnati  (EMSL-Cincinnati) conducts research
to:

      o    Develop and evaluate analytical  methods to identify and measure the
          concentration of chemical pollutants in drinking waters, surface
          waters, groundwaters,  wastewaters, sediments, sludges, and solid
          wastes.

      o    Investigate methods for the identification and measurement of
          viruses, bacteria and  other microbiological organisms in aqueous
          samples and to determine the responses of aquatic organisms to water
          quality.

      o    Develop and operate a  quality assurance program to support the
          achievement of data quality objectives in measurements of pollutants
          in drinking water, surface water, groundwater, wastewater, sediment
          and solid waste.

      This EMSL-Cincinnati publication, "Methods for the Determination of
Metals in Environmental Samples" was prepared to gather together under a
single cover a set of 13 laboratory analytical  methods for metals in a variety
of sample types.   We are pleased to provide this manual  and believe that it
will  be of considerable value to many public and private laboratories that
wish  to determine metals in environmental media for regulatory or other
reasons.
                                        Thomas A.  Clark,  Director
                                        Environmental  Monitoring Systems
                                        Laboratory - Cincinnati

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                                   ABSTRACT


     Thirteen analytical methods covering 35 analytes which may be present in
a variety of environmental sample types are described in detail.  Three of
these methods are sample preparation procedures that require a separate
determinate step found in other methods in this manual or elsewhere.  These
methods involve a wide range of analytical instrumentation including
inductively coupled plasma (ICP)/atomic emission spectroscopy (AES), ICP/mass
spectroscopy (MS), atomic absorption (AA) spectroscopy, ion chromatography
(1C), and high performance liquid chromatography (HPLC).  Application of these
techniques to a diverse group of sample types is a somewhat unique feature of
this manual.  Sample types include waters ranging from drinking water to
marine water as well as industrial and municipal wastewater, groundwater and
landfill leachate.  Also included are methods that will accommodate biological
tissues, sediments, and soils.
                                      IV

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                               TABLE OF CONTENTS
Method
Number






200.1
200.2
Title Revision Date
Disclaimer 	 	
Foreword 	
Abstract 	 	
Analyte - Method Cross Reference 	
Acknowledgement. . . . 	
Introduction and General Comments ....
Determination of Acid Soluble 2.0 4/91
Metals
Sample Preparation Procedure for 2.3 4/91
Page





1
3
13
         Spectrochemical Determination of
         Total Recoverable Elements

200.3    Sample Preparation Procedure for         1.0
         Spectrochemical Determination of Total
         Recoverable Elements in Biological
         Tissues

200.7    Determination of Metals and Trace        3.3
         Elements in Water and Wastes by
         Inductively Coupled Plasma-Atomic
         Emission Spectrometry

200.8    Determination of Trace Elements in       4.4
         Water and Wastes by Inductively
         Coupled Plasma - Mass Spectrometry

200.9    Determination of Trace Elements by       1.2
         Stabilized Temperature Graphite Furnace
         Atomic Absorption Spectrometry

200.10   Determination of Trace Elements in       1.4
         Marine Waters by On-Line Chelation
         Preconcentration and Inductively
         Coupled Plasma - Mass Spectrometry

200.11   Determination of Metals in Fish          2.1
         Tissue by Inductively Coupled Plasma-
         Atomic Emission Spectrometry
4/91




4/91




4/91



4/91



4/91




4/91
 23
 31
 83
123
153
177

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218.6    Determination of Dissolved Hexavalent    3.2       4/91        211
         Chromium in Drinking Water,
         Groundwater, and Industrial Wastewater
         Effluents by Ion Chromatography

245.1    Determination of Mercury in Water by     2.3       4/91        227
         Cold Vapor Atomic Absorption
         Spectrometry

245.3    Determination of Inorganic Mercury       1.1       4/91        241
         (II) and Selected Organomercurials
         in Drinking and Ground Water by High
         Performance Liquid Chromatography
         (HPLC) with Electrochemical Detection
         (ECD)

245.5    Determination of Mercury in Sediment     2.3       4/91        267
         by Cold Vapor Atomic Absorption
         Spectrometry

245.6    Determination of Mercury in Tissues      2.3       4/91        281
         by Cold Vapor Atomic Absorption
         Spectrometry
                                      VI

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                                ACKNOWLEDGEMENT

     This methods manual was prepared and assembled by the Inorganic Chemistry
Branch of the Chemistry Research Division, Environmental-Monitoring Systems
Laboratory - Cincinnati.  John Creed, Otis Evans, Larry Lobring, Theodore
Martin and Billy Potter were major contributors to this effort.  Special
thanks and appreciation are due to Diane Schirmann, Patricia Hurr and Helen
Brock for providing outstanding secretarial and word processing support and
for format improvements in presentation of the manual.  James O'Dell is also
recognized for his contributions in both methods development and design of
this manual's cover.

     In addition, Elizabeth Arar and Stephen Long, Technology Applications,
Inc., and William McDaniels, USEPA Region 4, are recognized for their
significant contributions.  Finally, all method authors and contributors wish
to thank William Budde, Director of the Chemistry Research Division, and
Thomas Clark, Director of the Environmental Monitoring Systems Laboratory -
Cincinnati, for their cooperation and support during this project.

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                                 INTRODUCTION

     An integral component of the role of the Environmental Protection Agency
(EPA) in assessing and protecting the quality of the environment is the
provision of means for monitoring environmental quality.  In keeping with this
role, EPA develops and disseminates analytical methods for measuring chemical
and physical parameters affecting this most important resource, including
contaminants which may have potential adverse effects upon the health of our
environment.  This manual provides 13 analytical methods for 35 analytes which
may be present in a variety of environmental sample types.  Three of the
methods are sample preparation procedures that refer to instrumental
techniques in other methods for multi-analyte or single-analyte quantitation.
The remaining 11 analytical methods were written to stand-alone, that is, each
method may be removed from the manual, photocopied, inserted into another
binder, and used without loss of information.  Revisions of these methods will
be made available in a similar stand-alone format to facilitate the
replacement of existing methods as new technical developments occur.  This
flexibility comes at the cost of some duplication of material, for example,
the definitions of terms section of each method is nearly identical.  The
authors believe that the added bulk of the manual is a small price to pay for
the format flexibility.

     An important feature of the methods in this manual is the consistent use
of terminology, and this feature is especially helpful in the quality control
sections where standardized terminology is not yet available.  The terms were
carefully selected to be meaningful without extensive definition, and
therefore should be easy to understand and use.  The names of authors of the
methods are provided to assist users in obtaining direct telephone support
when required.
                               GENERAL  COMMENTS

     The methods in this manual are not intended to be specific for any single
EPA regulation, compliance monitoring program, or specific study.  In the
past, manuals have been developed and published that respond to specific
regulations, such as the Safe Drinking Water Act (SDWA) or to special studies
such as the Environmental Monitoring and Assessment Program (EMAP) Near
Coastal Demonstration Project.  These methods are,  however, available for
incorporation into several regulatory programs due to their applicability to
such diverse sample types.  The ICP/AES, ICP/MS and AA methods have been or
will be approved for use in the drinking water and the permit programs.  The
methods applicable for use in marine and estuary waters will be available for
use in the Agency's National  Estuary Program and subsequent EMAP studies that
may involve the determination of toxic metals in the water column.

     The quality assurance sections are uniform and contain minimum
requirements for operating a reliable monitoring program: initial
demonstration of performance, routine analyses of reagent blanks, analyses of
fortified reagent blanks and fortified matrix samples, and analyses of quality
control (QC) samples.  Other QC practices are recommended and may be adopted
to meet the particular needs of monitoring programs e.g., analyses of field
reagent blanks, instrument control samples and performance evaluation samples.

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              METHOD  200.1

   DETERMINATION OF ACID-SOLUBLE METALS
  Theodore D. Martin and James W. O'Dell
         Inorganic Chemistry Branch
        Chemistry Research Division

                    and

              Gerald D. McKee
          Office of the Director
               Revision 2.0
                April  1991
ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
    OFFICE OF RESEARCH AND DEVELOPMENT
   U.S.  ENVIRONMENTAL PROTECTION AGENCY
          CINCINNATI, OHIO  45268

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                                METHOD 200.1

                    DETERMINATION OF ACID-SOLUBLE METALS


1.   SCOPE AND APPLICATION

     1.1  This method can be used to determine acid-soluble metals1 in ambient
          waters and aqueous wastes.  Results from this method may be used to
          calculate or estimate the potential impact on aquatic life and water
          quality. It is applicable to the analysis of arsenic (As), cadmium
          (Cd), chromium (Cr), copper (Cu), and lead (Pb).

     1.2  This method provides instructions for sample handling, preservation,
          and preparation prior to analysis using spectrochemical methods
          given in this manual.  Specific references are listed in Sect. 11.3
          of this method.

     1.3  This method is designed to be a supplement to approved EPA
          spectrophotometric and spectrochemical methods, however, it does not
          provide for oxidation state or organometallic speciation.  For a
          summary and description of the analytical techniques employed, their
          estimated instrumental detection limits, definition of terms
          specific to each technique, types of interferences encountered,
          instrumental requirements, reagents and standards required for
          analysis, calibration, general instrumental operating procedures,
          instrumental quality control, data calculation and reporting, see
          appropriate parts of the methods referenced in Sect. 11.3 of this
          method.

2.   SUMMARY OF METHOD

     2.1  This method describes procedural instruction for treating an
          aqueous sample for determination of acid-soluble metals prior to
          either atomic absorption or atomic emission spectrochemical
          analysis.  The aqueous sample is acidified to a pH of 1..75 ±0.1 and
          held for a period of at least 16 h before being filtered through a
          0.45-#m membrane filter and appropriately processed for analysis.

3.   DEFINITIONS

     3.1  Acid-Soluble Metal:  That portion of the metal concentration that
          will pass through a 0.45-jum membrane filter after the solution to
          be filtered has been adjusted to within a pH 1.75 ±0.1 and held for
          a period of 16 h.

4.   INTERFERENCES

     4.1  Contamination is of primary concern in determining acid-soluble
          metals.  All sample containers, labware, filtering and sample
          processing apparatus should be washed as described in Sect. 8.1.

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5.   SAFETY

     5.1  Ammonium hydroxide and nitric acid are moderately toxic and
          irritating to skin and mucus membranes.  Use concentrated reagents
          in a hood and if eye or skin contact occurs, flush with large
          volumes of water.  Always wear safety glasses or a shield for eye
          protection when working with these reagents.

6.   APPARATUS

     6.1  pH Meter-laboratory or field model:  A wide variety of instruments
          are commercially available with various specifications and optional
          equipment. The instrument must be capable of measuring pH to 0.1
          units and should be a meter equipped with a combination electrode.

     6.2  Filter funnel and support:  Only glass or plastic filtering
          apparatus should be used.  The support should be capable of
          accepting both the prefilter and fine filter while maintaining a
          no-leak seal between the funnel and support.  The Gelman model 4201
          or equivalent is acceptable.

     6.3  Suction flask, 500-mL capacity.

     6.4  Membrane filter discs:  Because the sample solution to be filtered
          will be of low pH (1.75 ±0.1), the filter media may be either a
            polyvinyl chloride acrylic copolymer or mixed esters of cellulose
            material.  The following 47-mm membrane filters or equivalent are
            acceptable.

          6.4.1   Fine prefilter:  DM-800, 0.8-jum (Gelman No.64502)

          6.4.2   Fine filter:  DM-450, 0.45-/Jtn  (Gelman No. 64515) or
                  HAWP-047, 0.45 /im (Millipore No. HAWP 047 00)

     6.5  Sample collection containers:  Cubitainer, polyethylene, 1 quart
          (0.95L) capacity or equivalent.

     6.6  Sample storage bottles:  Wide-mouth high-density polyethylene with
          polypropylene screw cap closure, 500-mL capacity.

     6.7  Glassware:  Class A volumetric flasks  and pipets of various volumes.

     6.8  For the apparatus and equipment needed for the analytical technique
          employed, see the specific references.

7.   REAGENTS AND STANDARDS

     7.1  Deionized, distilled water:  Prepare by passing distilled water
          through a mixed  bed of cation  and  anion exchange resins.  Use
          deionized, distilled water for the preparation of all  reagents and
          as dilution or rinse water.  The purity of this water  must be
          equivalent to ASTM Type  II reagent water of Specification D 1193  .

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     7.2  Nitric acid, cone,  (sp.gr. 1.41), ultra-high purity grade or
          equivalent.  Redistilled acid is acceptable.

          7.2.1   Nitric acid,  (1+1):  Add 500 mL cone. HNO, (Sect. 7.2) to
                  400 mL deionized, distilled water (Sect. 7.1) and dilute to
                  •L L. •

     7.3  Hydrochloric acid,  cone. (sp. gr. 1.19).

          7.3.1   Hydrochloric  acid, (1+1):  Add 500 ml cone. HC1  (Sect. 7.3)
                  to 400 ml deionized, distilled water (Sect. 7.1) and dilute
                  to 1 L.

     7.4  Ammonium Hydroxide, (1+9):  Dilute 10 ml cone, ammonium hydroxide,
          NH4OH (analytical  reagent grade),  to 100 ml  with deionized,
          distilled water (Sect. 7.1).

     7.5  Buffer solutions:  Two buffer solutions are required, one in the
          range of pH 2 and the other at pH 7.  These may be prepared or
          purchased as commercially available certified solutions.  The use
          of purchased buffer solutions certified at a pH of 2 and 7 is
          recommended.

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  For the determination of acid-soluble metals, contamination and
          loss are of prime concern.  Dust in the laboratory environment,
          impurities in reagents and improperly cleaned laboratory apparatus
          which the sample contacts are all  potential  sources of
          contamination.   Sample containers can introduce either positive or
          negative errors in the measurement of metals by (a) contributing
          contaminants  through leaching or surface desorption and/or (b) by
          depleting concentration through adsorption.   Laboratory glassware,
          including the sample collection cubitainer and the polyethylene
          sample storage  bottle, as well  as the filtering apparatus should be
          thoroughly washed with detergent and tap water;  thoroughly rinsed
          with (1+1) nitric acid, tap water,  (1+1) hydrochloric acid,  tap
          water and finally deionized distilled water  in that order (See
          Notes 1 and 2).

          NOTE 1:  To remove difficult organic deposits from glassware,  a
          commercial product,  NOCHROMIX,  available from Godax Laboratories,
          480 Canal  Street,  New York,  New York  10013  may be used.  This
          product should  not be used on plastic containers or filtering
          apparatus.

          NOTE 2:  If it  can be documented through an  active analytical
          quality control program using spiked samples,  laboratory control
          standards  and reagent blanks  that  certain steps  in the cleaning
          procedure  are not required,  those  steps may  be eliminated from the
          procedure.

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     8.2  At the time of sample collection,  the sample cubitainer is rinsed
          with the sample solution and the rinse portion discarded.   The
          cubitainer is then filled with approximately 800 ml of sample,
          acidified with 2 ml of (1+1) nitric acid and mixed.  For most
          ambient waters the acid addition will lower the pH to near 2, but
          not lower than 1.75.  The cubitainer is sealed, placed in an ice
          chest at 4°C, and returned to the laboratory.  Note the date and
          time of preservation on the sample tag.

     8.3  The sample should not be held more than 3 days at 4°C from the day
          of collection before processing is started.  The filtrate is
          estimated to be stable for 30 days.

9.   CALIBRATION AND STANDARDIZATION
     9.1
     9.2
          Calibration of pH meter -  Because of the  wide  variety of pH meters
          and accessories,  detailed  operating  procedures cannot be
          incorporated into this method.   Each analyst must  be  acquainted
          with the operation of the  system being used and familiar with  all
          instrument functions.   Special  attention  to care of the combination
          electrode is recommended.   See  Method 150.1 given  in  EPA
          600/4-79-020,  March 19832.

          Each instrument/electrode  system must be  calibrated at a
          minimum of two points, one at or near pH  2, the other at pH 7.
          Calibrate according to manufacturer's instructions and measure the
          pH of each sample.  Using  deionized  distilled  water (Sect.  7.1),
          rinse the electrode system after each pH  measurement.

10.   QUALITY CONTROL

     10.1 The following quality assurance procedures represent  5% of  the
           analyzed sample load for  20 samples.

     10.2 To measure recovery and cross contamination between samples that
          may occur, 300 ml of a laboratory control standard containing  all
          six metals, each at a concentration  above 10X  its  determined method
          detection limit (MDL), is  transferred to  a cleaned cubitainer,
          adjusted to a pH range of  1.75  ± 0.1 and  allowed to stand for  a
          minimum of 16 h.   At a selected point midway through  the group of
          samples to be analyzed, the control  standard  is filtered.  The
          analyzed values should be  within the warning limits of ±2 standard
          deviations of an established mean value as determined from  seven
          prior replicate analyses.   If an analyzed value was greater than  ±3
          standard deviations from the mean, the analysis was out of  control.

     10.3 To determine the MDL of each metal,  prepare seven  aliquots  of  the
          sample matrix of concern,  spike the  aliquots with  each metal to a
          concentration of 3 to 5 times its estimated detection limit and
          follow the procedure - "Definition and Procedure for  the
          Determination of the Method Detection Limit.

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11.  PROCEDURE

     11.1 SAMPLE pH ADJUSTMENT - For the determination of acid-soluble
          metals, the pH of the sample must be 1.75 ± 0.1.   Upon receiving the
          sample in the laboratory, check the sample tag for proper
          preservation and to see that the holding time has not been
          exceeded.  Allow the sample to come to room temperature,  calibrate
          the pH meter and measure the pH of the sample in  the cubitainer.
          Using deionized distilled water (Sect. 7.1), rinse the electrode
          system after each pH measurement.  Do not wipe the electrode.

          11.1.1  If the sample pH is between 1.65 and 1.85, mix the sample
                  and allow to stand at room temperature for a minimum of
                  16 h for required dissolution.  At the end of the extraction
                  period, measure the pH again to verify that the proper pH
                  was maintained, and if so, filter according to paragraph
                  11.2.  If pH was not maintained, a new sample should be
                  requested and more care and time taken in the initial  pH
                  adjustment.

          11.1.2  If the sample pH is above 1.85, add (1+1) nitric  acid  in a
                  dropwise manner, mix the sample in the cubitainer by
                  inverting and shaking and redetermine the pH.   Continue
                  adding small  increments of the (1+1) nitric acid  and mix
                  until the sample is within the desired pH range.   If the
                  pH should go below 1.65,  add (1+9) ammonium hydroxide
                  (Sect. 7.3) in a dropwise manner until  the sample is within
                  the pHrange of 1.65 to 1.85.  Once the pH of the  sample is
                  properly adjusted and thoroughly mixed, set the sample
                  aside for a minimum of 16 h for the required
                  dissolution to occur.  At the end of the  extraction
                  period, measure the pH again to verify the proper pH was
                  maintained, and if so,  filter according to paragraph 11.2.
                  If pH was not maintained,  a new sample should  be
                  requested and more care and time taken in the  initial  pH
                  adjustment.

          11.1.3  If upon receipt the sample has a pH below 1.65, the
                  sample should be discarded and the collection  of  a new
                  sample requested.   The sample collection  team  should be
                  informed of the reason  why the previous sample was
                  rejected.

     11.2 SAMPLE FILTRATION - For determination of acid-soluble  metals,
          the pH-adjusted sample is  filtered through a 0.45-jum membrane
          filter.   To prevent clogging  of the filter,  the sample is first
          passed through a fine prefilter.

          11.2.1  Before filtering any  sample make certain  that  the
                  filtering apparatus (Sects.  6.2 and  6.3),  polyethylene
                  storage bottles (Sect.  6.7)  and other necessary glassware
                  have been cleaned  by  the  procedure described  in Sect.  8.1.

                                      8

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      11.2.2   Insert the filter support of the filtering  apparatus through
              the proper size rubber stopper and wrap the stopper with
              1  in. PTFE laboratory tape to prevent contamination.  Secure
              the flask in an upright position and place  the support  in
              the neck of the suction flask.  Connect the suction flask to
              the vacuum line.

      11.2.3   Place the membrane filters (Sect. 6.4) on the filter support
              in the following order:  first the 0.45-/zm  fine filter  and
              then the 0.8-pi prefilter.  Assemble the filter funnel  to
              the support as recommended by the manufacturer.

      11.2.4   Do not mix the sample, but carefully decant approximately
              50 ml of sample from the cubitainer into the filtering
              funnel and apply the vacuum.  After filtration, break the
              vacuum, remove the filtering apparatus, rinse the suction
              flask with the filtrate and discard.

      11.2.5   Reassemble the filtering apparatus and suction flask,
              reapply the vacuum and carefully decant approximately 250 ml
              of additional sample into the filtering apparatus.

      11.2.6  When filtration is complete, break the vacuum, transfer
             the filtrate to a labeled, cleaned, polyethylene storage
              bottle (Sect. 6.7) and store until  all  analyses have been
             completed,  not to exceed 30 days.   The remaining unfiltered
             portion of the sample may be discarded.

      11.2.7  Before filtering additional  samples, discard the filters,
             rinse the suction flask and filtering apparatus with copious
             amounts of deionized distilled water (Sect.  7.1),  discard
             the rinse water and drain away any excess water.

     11.2.8  Repeat the  above procedure until  all samples and quality
             control  aliquots have been filtered.

11.3 SAMPLE ANALYSES - The level  of metal  concentration will   determine
     the analytical  method selected to complete  the  analysis.

     11.3.1  Inductively  coupled plasma-atomic  emission (ICP)
             spectrometric analyses -  The acid-soluble metals  As,  Cd, Cr,
             Cu and Pb can be analyzed by direct aspiration ICP
             spectrometry using the procedure described in  Method 200.7
             of this  manual.   To prepare  the  sample  for analyses,  pipet
             2 mL (1+1) hydrochloric  acid  into  a 50-mL volumetric flask
             and dilute to the mark with  sample  filtrate.  This dilution
             requires  an  appropriate  factor be  applied to the  final
             calculations.   In the absence  of an established  MDL
             (Sect.  10.2.1),  the  following  estimated  instrumental
             detection limit  for  each  element should  be considered  the
             limit  of  analysis.

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                                  Estimated Detection Limit
                Element           	mg/L	

                   As                      0.03
                   Cd                      0.02
                   Cr                      0.007
                   Cu                      0.003
                   Pb                      0.03

11.3.2  Direct aspiration flame atomic absorption (FLAA) analyses
        - The acid-soluble metals Cd,  Cr,  Cu and Pb can be
        analyzed by procedures given in approved FLAA methods
        without requiring additional processing of the filtrate
        before analysis.  Listed below are the method numbers and
        estimated instrumental detection limits, which in the
        absence of an established MDL (Sect. 10,2.1), should be
        considered the FLAA limit of analysis for direct aspiration.
        In addition to the individual  methods, for the proper
        analysis procedure, see parts 9.1  of Section 200.0:
        Atomic Absorption Methods given in EPA 600/4-79-020,
        March 19832 .

                               Method         Estimated Detection
          Element              Number           Limit. mq/L	

            Cd                  213.1                0.005
            Cr                  218.1                0.05
            Cu                  220.1                0.02
            Pb                  239.1                0.1

11.3.3  Stabilized Temperature Graphite Furnace Atomic Absorption
        (STGFAA) ANALYSES - For STGFAA analysis of the acid-soluble
        metals As, Cd, Cr, Cu and Pb,  an aliquot of the filtrate
        must be treated with the appropriate matrix modifiers
        before analysis.  For proper instrumental STGFAA calibration
        and suggested operating conditions see Method 200.9 of this
        manual.  In the absence of an established MDL
        (Sect. 10.2.1), the following estimated STGFAA instrumental
        detection limit for each element should be considered the
        limit of anaysis.

                                    Estimated Detection Limit
             El ement                	ng/L	

               As                             0.9
               Cd                             0.05
               Cr                             0.2
               Cu                             1.0
                            10

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12.  CALCULATIONS

     12.1 See the appropriate section of the recommended methods of analysis.

     12.2 Final results of these calculations should be reported as mg/L acid-
          soluble metal.

13.  PRECISION AND RECOVERY

     13.1 Precision and recovery data for Cd, Cr, Cu, and Pb by this method
          using inductively coupled plasma-atomic emission spectrometric
          analyses are given in Table 1.  The data are for three levels of
          concentration using varying amounts of the same sludge material
          spiked into river water.  Seven replicate samples were prepared for
          each level  of concentration.  River water controls were subtracted
          from each level  of spike.  The percent recovery calculation is based
          on "total-recoverable" analysis of the same samples.  Accuracy data
          on actual samples cannot be obtained.

     13.2 Precision data  on the determination of acid-soluble metals by this
          method using atomic absorption spectrophotometric analyses are
          estimated to be similar to the data in the methods referenced.

14.  REFERENCES

     1.    Water Quality Criteria; Availability of Documents, Federal Register,
          Vol. 50, No. 145, July 29, 1985,  pp. 30784-30796.

     2.    Chemical Analysis of Water and Wastes, EPA 600/4-79-020,  (Revised,
          March 1983), U.S. Environmental Protection Agency, Office of
          Research and Development, Environmental Monitoring and Support
          Laboratory, Cincinnati, Ohio.

     3.    Annual Book of  ASTM Standards, Part 31, American Society  for Testing
          and Materials,  1916 Race St.,  Philadelphia, PA, 19103.

     4.    Code of Federal  Regulations 40, Ch. 1, Pt. 136 Appendix B.
                                      11

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                  METHOD 200.2

SAMPLE PREPARATION PROCEDURE FOR SPECTROCHEMICAL
  DETERMINATION OF TOTAL RECOVERABLE ELEMENTS
       Theodore D. Martin, John T. Creed
           Inorganic Chemistry Branch
          Chemistry Research Division

                      and

                Stephen E. Long
         Technology Applications, Inc.
                  Revision 2.3
                   April  1991
  ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
       OFFICE  OF RESEARCH AND DEVELOPMENT
     U. S. ENVIRONMENTAL PROTECTION AGENCY
            CINCINNATI, OHIO  45268
                       13

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                                 METHOD 200.2

        SAMPLE PREPARATION PROCEDURE FOR SPECTROCHEMICAL  DETERMINATION
                         OF TOTAL RECOVERABLE ELEMENTS
1.   SCOPE AND APPLICATION

     1.1  This method provides sample preparation  procedures  for the
          determination of total recoverable  elements  in  groundwaters,  surface
          waters, drinking waters, wastewaters,  and, with the exception of
          silica, sediments,  sludges and  solid waste samples.

     1.2  This method is applicable to  the  following analytes:
             Analyte

            Aluminum
            Antimony
            Arsenic
            Boron
            Barium
            Beryl 1i urn
            Cadmium
            Calcium
            Chromi urn
            Cobalt
            Copper
            Iron
            Lead
            Lithium
            Magnesium
            Manganese
            Mercury
            Molybdenum
            Nickel
            Phosphorus
            Potassium
            Selenium
            Silica
            Silver
            Sodium
            Strontium
            Thallium
            Thorium
            Tin
            Uranium
            Vanadium
            Zinc
            Chemical  Abstract Services
            Registry Numbers (CASRW
(Al)
(Sb)
(As)
(B)
(Ba)
(Be)
(Cd)
(Ca)
(Cr)
(Co)
(Cu)
(Fe)
(Pb)
(Li)
(Mg)
(Mn)
(Hg)
(Mo)
(Ni)
(P)
(K)
(Se)
(Si02)
(Ag)
(Na)
(Sr)
(Tl)
(Th)
(Sn)
(U)
(V)
(Zn)
7429-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7439-
7439-
7439-
7439-
7439-
7439-
7439-
7440
7723
7440
7782
7631
7440
7440
7440
7440
7440
7440
7440
7440
7440
90-5
36-0
38-2
•42-8
•39-3
•41-7
•43-9
-70-2
•47-3
•48-4
-50-8
-89-6
-92-1
-93-2
-95-4
-96-5
-97-6
-98-7
-02-0
-14-0
-09-7
-49-2
-86-9
-22-4
-23-5
-24-6
-28-0
-29-1
-31-5
-61-1
-62-2
-66-6
                                       14

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 1.3  Samples  prepared  by this method can be analyzed by the following
     methods  given  in  this manual:  Method 200.7, Determination of Metals
     and Trace  Elements by Inductively Coupled Plasma-Atomic Emission
     Spectrometry;  Method 200.8, Determination of Trace Elements By
     Inductively Coupled Plasma-Mass Spectrometry; and Method 200.9,
     Determination  of  Trace Elements by Stabilized Temperature Graphite
     Furnace  Atomic Absorption Spectrometry.  Also, the direct aspiration
     flame atomic absorption methods given in "Methods for Chemical
     Analysis of Water and Wastes", EPA 600/4-79-020, March 1983 can be
     used for analysis.  See the analytical methodology mentioned for
     selection  of the  appropriate method for the determination of a
     specific analyte.
1.4
1.5
1.6
1.7
 This method  is  applicable  to the  preparation of drinking water
 samples  for  the determination of  metal  and metalloid contaminants.
 However,  it  can only  be  used prior to  an approved  analytical method
 for compliance  monitoring  when  included in the approved method or
 when listed  as  a separately approved method in the Federal Register.
 It should  be noted that  some primary drinking water metal
 contaminants require  that  a 4X  preconcentration be used prior to
 analysis  instead of the  2X preconcentration described  in this
 method.

 This method  is  suitable  for preparation of aqueous samples
 containing silver concentrations  up to 0.1 mg/L.   For  the analysis
 of wastewater samples containing  higher concentrations of silver,
 succeeding smaller volume, well mixed aliquots must be prepared
 until the analysis solution contains < 0.1 mg/L silver.

 When using this  method for determination of boron  and  silica in
 aqueous samples,~only plastic or  quartz labware should be used from
 the time of  sample collection to  the completion of the analysis.
 For accurate determinations of  boron in solid sample extracts at
 concentrations  below  100 mg/Kg, only quartz beakers should be used
 in the digestion  with the  immediate transfer of an extract aliquot
 to a plastic centrifuge tube following dilution of the digestate to
 volume. For  these determinations,  borosilicate glass must not be
 used in order to  avoid sample contamination of these analytes from
 the glass.

 This method will  solubilize and hold in solution only minimal
 concentrations of barium,  as barium sulfate.   In addition,  the
 stability of solubilized barium is greatly affected when free
 sulfate is available in solution.   The concentration of barium that
will  remain  in solution decreases  as the free sulfate concentration
 increases.   [For example, when a 100 ml aliquot of drinking water
containing 60 mg/L sulfate was fortified with 5 mg of BaSO,  salt
 (equivalent to 59 mg/L Ba  in the 2X analysis  solution)  only 33 mg/L
Ba was initially solubilized using the procedure given  in Sect.
 11.2.   Upon standing one week,  the barium concentration decreased to
 12 mg/L.  When 100 mL of deionized  distilled water was fortified,  the
entire 5  mg of BaS04 was  solubilized  and remained  in  solution  over
                                 15

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          the same time period.]  For more accurate determinations of barium
          in samples having varying and unknown concentrations of sulfate,
          samples should be analyzed as soon as possible after preparation is
          completed.

2.   SUMMARY OF METHOD

     2.1  Solid and aqueous samples are prepared in a similar manner for
          analysis.  Metals and toxic elements are extracted from either solid
          samples or the solid phase portion of aqueous samples by refluxing
          the sample for 30 min in a mixture of nitric and hydrochloric acids.
          After extraction, the solubilized analytes are diluted to specified
          volumes with ASTM type I water.  Diluted samples are to be analyzed
          by mass and/or atomic spectrometry methods as soon as possible after
          preparation.

3.   DEFINITIONS

     3.1  TOTAL RECOVERABLE - The concentration of analyte determined to be in
          either a  solid sample or an unfiltered aqueous sample following
          treatment by refluxing with hot dilute mineral acid.

4.   INTERFERENCES

     4.1  In sample preparation, contamination is of prime concern.  The work
          area, including  bench top and fume hood, should be periodically
          cleaned in order to eliminate environmental contamination.

     4.2  Chemical  interferences are matrix dependent and cannot be documented
          previous  to analysis.

     4.3  Boron and silica from the glassware will grow into the sample
          solution  during  and following sample processing.  For critical
          determinations of boron and silica, only quartz and/or plastic
          labware should be used.  When quartz beakers are not available  for
          digestion of solid samples, to  reduce boron contamination,
          immediately transfer  an aliquot of the diluted digestate to a
          plastic centrifuge tube for storage until time of analysis. A series
          of laboratory reagent blanks can  be used to monitor and  indicate  the
          contamination effect.

5.   SAFETY

     5.1  All  personnel handling environmental samples  known  to contain or  to
          have been in contact  with  human waste should  be immunized  against
          known disease causative agents.

     5.2  Material  safety  data  sheets  for all chemical  reagents should be
          available to and understood  by  all  personnel  using  this  method.
          Specifically, concentrated  hydrochloric  acid  and concentrated nitric
          acid are  moderately toxic  and  extremely  irritating  to skin  and  mucus
          membranes.   Use  these reagents  in a  hood whenever possible  and  if

                                       16

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          eye or skin contact occurs, flush with large volumes of water
          Always wear safety glasses or a shield for eye protection when
          working with these reagents.2'3'4

6.   APPARATUS AND EQUIPMENT

     6.1  LABWARE - For determination of trace levels of elements,
          contamination and loss are of prime consideration.  Potential
          contamination sources include improperly cleaned laboratory
          apparatus and general contamination within the laboratory
          environment from dust, etc.  A clean laboratory work area designated
          for trace element sample handling must be used.  Sample containers
          can introduce positive and negative errors in the determination of
          trace elements by (1) contributing contaminants through surface
          desorption or leaching,  (2) depleting element concentrations through
          adsorption processes.  All reusable labware (glass,  quartz,
          polyethylene,  Teflon, etc.),  including the sample container, should
          be cleaned prior to use.   Labware should be soaked overnight and
          thoroughly washed with laboratory-grade detergent and  water, rinsed
          with water,  and soaked for four hours in a mixture of  dilute nitric
          and hydrochloric acid (1+2+9),  followed by rinsing with water,  ASTM
          type I  water and oven drying.

          NOTE:   Chromic acid must  not  be used for cleaning glassware.

          6.1.1   Labware - Volumetric flasks,  graduated cylinders,  funnels  and
                 centrifuge tubes  (glass  and/or metal  free  plastic).

          6.1.2   Assorted calibrated pipettes.

          6.1.3   Conical  Phillips beakers,  250-mL  with  50-mm watch  glasses.
                 Griffin  beakers, 250-mL  with  75-mm  watch glasses.
                 Teflon  and/or  quartz beakers,  250-mL with  Teflon covers
                 (optional).

          6.1.4   Wash  bottle  -  One piece  stem,  Teflon FEP bottle with  Tefzel
                 ETFE  screw closure,  125-mL capacity.

    6.2   SAMPLE  PROCESSING EQUIPMENT

          6.2.1   Hot plate: Ceramic  top, graduated dial 90°C to 450°C
                 (Corning  PC100 or equivalent).

          6.2.2   Single pan balance:  Balance capable of weighing to the
                 nearest 0.01 g.

          6.2.3  Analytical balance:  Balance capable of weighing to the
                nearest 0.0001 g.
                                     17

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          6.2.4  Centrifuge:  Steel cabinet with guard bowl,  electric timer
                 and brake.  (International Centrifuge, Universal  Model  UV or
                 equivalent.)

          6.2.5  Drying oven:  Gravity convection oven, with thermostatic
                 control capable of maintaining 180°C ±'5°C.

7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1  Reagents may contain elemental impurities which might affect
          analytical data.  High-purity reagents should be used whenever
          possible.  All acids used for this method must be of ultra high-
          purity grade.

          7.1.1  Nitric acid, concentrated (sp.gr. 1.41).

          7.1.2  Nitric acid (1+1) - Add 500 ml cone, nitric acid to 400 ml of
                 ASTM type  I water and dilute to 1 L.
                    \
          7.1.3  Hydrochloric acid, concentrated (sp.gr. 1.19).

          7.1.4  Hydrochloric acid (1+1) - Add 500 ml cone, hydrochloric acid
                 to 400 ml  of ASTM type I water and dilute to 1 L.

          7.1.5  Hydrochloric acid (1+4) - Add 200 ml cone, hydrochloric acid
                 to 400 ml  of ASTM type I water and dilute to 1 L.

     7.2  WATER -  For all  sample preparation and dilutions, ASTM type I water
          (ASTM D1193)5 is required.   Suitable water may be prepared by
          passing  distilled water through  a mixed bed of anion and cation
          exchange resins.

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  For determination of total recoverable elements  in aqueous samples,
          acidify  with  (1+1) nitric acid at the time of collection to pH <2
          normally, 3 ml  of (1+1)  nitric acid per liter of sample is
          sufficient for  most ambient  and  drinking water samples).  The sample
          should not be filtered prior to  analysis.

          NOTE:  Samples  that cannot be acid preserved at  the time of
          collection because of sampling limitations or transport
          restrictions, should be  acidified with nitric acid to a pH <2 upon
          receipt  in the  laboratory.   Following acidification, the sample
          should be held  for 16 h  before withdrawing an aliquot for sample
          processing.

     8.2  Solid  samples usually require no preservation prior to  analysis
          other  than storage at 4°C.
                                       18

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9.   CALIBRATION AND STANDARDIZATION

     9.1  Not applicable.  Follow instructions given in the analytical  method
          selected.

10.  QUALITY CONTROL

     10.1 Each laboratory determining total  recoverable elements is required
          to operate a formal  quality control  (QC) program.  The minimum
          requirements of a QC program consist of an initial  demonstration of
          laboratory capability, and the analysis of laboratory reagent
          blanks, fortified blanks and quality control  samples as a continuing
          check on performance.  The laboratory is required to maintain
          performance records  that define the  quality of data generated.

     10.2 Specific instructions on accomplishing the described aspects  of the
          QC program are discussed in the analytical methods  (Sect. 1.3).

11.  PROCEDURE

     11.1 Sample Preparation - Aqueous Samples

          For determination of total recoverable elements in  water or
          wastewater, take a 100 mL (± 1 ml) aliquot from a well mixed, acid
          preserved sample containing not more than 0.25% (w/v) total solids
          and transfer to a 250-mL Griffin beaker.  (If total solids are
          greater than 0.25% reduce the size of the aliquot by a proportionate
          amount.)  Add 2 ml of (1+1) nitric acid and 1 ml of (1+1)
          hydrochloric acid.  Heat on a hot  plate at 85°C until the volume has
          been reduced to approximately 20 ml, ensuring that  the sample does
          not boil.  (A spare  beaker containing approximately 20 ml of  water
          can be used as a gauge).

              NOTE:  For proper heating adjust the temperature control  of the
              hot plate such that an uncovered beaker containing 50 ml  of
              water located in the center of the hot plate can be maintained
              at a temperature no higher than  85°C.  Evaporation time for
              100 ml of sample at 85°C is approximately two hours with  the
              rate of evaporation rapidly increasing as the sample volume
              approaches 20 ml.

          Cover the beaker with a watch glass  and reflux for  30 min. Slight
          boiling may occur but vigorous boiling should be avoided.  Allow to
          cool and quantitatively transfer to  either a  50-mL  volumetric flask
          or a'50-mL class A stoppered graduated cylinder. Dilute to volume
          with ASTM type I water and mix.  Centrifuge the sample or allow to
          stand overnight to separate insoluble material.  The sample is now
          ready for analysis by either inductively coupled plasma-atomic
          emission spectrometry or direct aspiration flame and stabilized
          temperature graphite furnace atomic  absorption spectroscopy
          (Sect. 1.3).   For analyses by inductively coupled plasma-mass
                                      19

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12.
     spectrometry, pipette 20 ml of the prepared solution into a 50-mL
     volumetric flask, dilute to volume with ASTM type I water and mix.
     (Internal standards are added at the time of analysis.)  Because the
     effects of various matrices on the stability of diluted samples
     cannot be characterized, all analyses should be performed as soon as
     possible after the completed preparation.

11.2 Sample Preparation - Solid Samples

     For determination of total recoverable elements in solid samples
     (sludge, soils, and sediments), mix the sample thoroughly to achieve
     homogeneity and weigh accurately a 1.0 ± 0.01 g portion of the
     sample.  Transfer to a 250-mL Phillips beaker.  Add 4 mL (1+1)
     nitric acid and 10 ml (1+4) hydrochloric acid.  Cover with a watch
     glass.  Heat the sample on a hot plate and gently reflux for 30 min.
     Very slight boiling may occur, however vigorous boiling must be
     avoided to prevent the loss of HC1-H20 azeotrope.

         NOTE:  For proper heating adjust the temperature control of the
         hot plate such than an uncovered Griffin beaker containing 50 ml
         of water located in the center of the hot plate can be
         maintained at a temperature approximately but no higher than
         85°C.

     Allow the sample to cool and quantitatively transfer to a 100-mL
     volumetric flask.  Dilute to volume with ASTM type I water and mix.
     Centrifuge the sample or allow to stand overnight to separate
     insoluble material.  The sample is now ready for analysis by either
     inductively coupled plasma-atomic emission spectrometry or direct
     aspiration flame and stabilized temperature graphite furnace atomic
     absorption spectroscopy (Sect. 1.3).  For analysis by inductively
     coupled plasma-mass spectrometry, pipette 10 ml into a 50-mL
     volumetric flask, dilute to volume with ASTM type I water and mix.
     (Internal standards are added at the time of analysis.)  Because the
     effects of various matrices on the stability of diluted samples
     cannot be characterized, all analyses should be performed as soon as
     possible after the completed preparation.

         NOTE:  Determine the percent solids in the sample for use in
         calculations and for reporting data on a dry weight basis.  To
         determine the dry weight transfer a separate,  uniform 1 gram
         aliquot to an evaporating dish and dry to a constant weight at
         103°-105°C.

11.3 Sample Analysis - Use an analytical method listed in Sect. 1.3.

CALCULATIONS

12.1 Not applicable.  Discussed in analytical methods listed in
     Sect. 1.3.
                                      20

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13.  PRECISION AND ACCURACY

     13.1 Not applicable.  Available data included in analytical methods
          listed in Sect. 1.3.

14.  REFERENCES

     1.    Martin,  T.D. and E.R. Martin, "Evaluation of Method 200.2 Sample
          Preparation Procedure for Spectrochemical Analyses of Total
          Recoverable Elements", December 1989, U.S.  Environmental Protection
          Agency,  Office of Research and Development, Environmental Monitoring
          Systems  Laboratory,  Cincinnati, Ohio  45268.

     2.    "OSHA Safety and Health Standards,  General  Industry", (29 CFR 1910),
          Occupational Safety  and Health Administration,  OSHA 2206, revised
          January  1976.

     3.    "Safety  in Academic  Chemistry Laboratories", American Chemical
          Society  Publication, Committee on  Chemical  Safety, 3rd Edition,
          1979.

     4.    "Proposed OSHA Safety and Health Standards, Laboratories",
          Occupational Safety  and Health Administration,  Federal  Register,
          July 24,  1986.

     5.    Annual Book of ASTM  Standards, Volume 11.01.
                                     21

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                           METHOD  200.3

         SAMPLE  PREPARATION PROCEDURE  FOR SPECTROCHEMICAL
DETERMINATION OF TOTAL RECOVERABLE ELEMENTS IN BIOLOGICAL TISSUES
                         William McDanlel

                 Environmental Services Division
                            Region IV
              U. S. Environmental Protection Agency
                           Revision 1.0
                            April  1991
                           Adapted by:
           ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
                OFFICE OF RESEARCH AND DEVELOPMENT
              U. S. ENVIRONMENTAL PROTECTION AGENCY
                     CINCINNATI, OHIO  45268
                                23

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                                 METHOD  200.3

        SAMPLE PREPARATION PROCEDURE  FOR SPECTROCHEMICAL  DETERMINATION
               OF TOTAL RECOVERABLE ELEMENTS IN  BIOLOGICAL  TISSUES
1.   SCOPE AND APPLICATION

     1.1  This method provides sample preparation  procedures  for the
          determination of total recoverable  elements  in  biological  tissue
          samples.
     1.2  This method is applicable to the  following  elements:


             Analyte
     1.3
            Aluminum
            Antimony
            Arsenic
            Barium
            Beryl 1i urn
            Cadmi urn
            Calcium
            Chromium
            Cobalt
            Copper
            Iron
            Lead
            Lithium
            Magnesium
            Manganese
            Mercury
            Molybdenum
            Nickel
            Phosphorus
            Potassium
            Selenium
            Silver
            Sodium
            Strontium
            Thallium
            Thorium
            Uranium
            Vanadium
            Zinc
                (Al)
                (Sb)
                (As)
                (Ba)
                (Be)
                (Cd)
                (Ca)
                (Cr)
                (Co)
                (Cu)
                (Fe)
                (Pb)
                (Li)
                (Mg)
                (Mn)
                (HG)
                (Mo)
                (Ni)
                (P)
                (K)
                (Se)
                (Ag)
                (Na)
                (Sr)
                (Tl)
                (Th)
                (U)
                (V)
                (Zn)
                            Chemical  Abstract Services
                            Registry Numbers
7429-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7439-
7439-
7439-
7439-
7439-
7439-
7439-
7440-
7723-
7440-
7782-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
-90-5
-36-0
-38-2
-39-3
-41-7
-43-9
-70-2
-47-3
-48-4
•50-8
-89-6
•92-1
•93-2
•95-4
•96-5
•97-6
•98-7
•02-0
•14-0
09-7
49-2
22-4
23-5
24-6
28-0
29-1
61-1
62-2
66-6
Samples prepared by this method can  be  analyzed  by  inductively
coupled plasma-atomic emission spectrometry  (ICP-AES)  Method 200.7,
"Determination of Metals and Trace Elements  by  Inductively Coupled
Plasma-Atomic Emission Spectrometry," inductively coupled  plasma-
mass spectrometry (ICP-MS) Method 200.8,  "Determination  of Metals
                                      24

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     and Trace Elements by Inductively Coupled Plasma-Mass Spectrometry,"
     and stabilized temperature platform graphite furnace atomic
     absorption (STGFAA), Method 200.9, "Determination of Trace Elements
     by Stabilized Temperature Graphite Furnace Atomic Absorption
     Spectrometry".  See analytical methods mentioned for selection of
     the appropriate method for determination of a specific analyte.

SUMMARY OF METHOD

2.1  Up to 5 g of a frozen tissue sample is transferred to a 125 mL
     flask.  The tissue is digested with nitric acid, hydrogen peroxide
     and heat.  This digestion results in a clear solution that is then
     analyzed by mass or atomic Spectrometry methods.  The determined
     metal concentration is reported in microgram/gram (/jg/g) wet tissue
     weight.

DEFINITIONS

3.1  TOTAL RECOVERABLE - The concentration of analyte determined to be in
     either a solid sample or an unfiltered aqueous sample following
     treatment by refluxing with hot dilute mineral acid.

3.2  LABORATORY REAGENT BLANK (LRB) - A solution of reagents that is
     treated exactly as a sample including exposure to all glassware and
     equipment that are used with other samples.  The LRB is used to
     determine if method analytes or other interferences are present in
     the laboratory environment, reagents, or apparatus.

INTERFERENCES

4.1  Chromium contamination of biological samples from the use of
     stainless steel has been reported.4  Use of special  cutting
     implements and dissecting board made from materials that are not of
     interest is recommended.  Knife blades made of titanium with Teflon
     handles have been successfully used.

4.2  In sample preparation, contamination is of prime concern.  The work
     area, including bench top and fume hood, should be periodically
     cleaned in order to eliminate environmental contamination.

4.3  Chemical interferences are matrix dependent and cannot be predicted.

SAFETY

5.1  All personnel handling environmental samples known to contain or to
     have been in contact with human waste should be immunized against
     known disease causative agents.

5.2  Material safety data sheets for all chemical reagents should be
     available to and understood by all personnel using this method.
     Concentrated nitric and hydrochloric acids are moderately toxic and
     extremely irritating to skin and mucus membranes.  Hydrogen peroxide

                                 25

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          is a strong oxidizing reagent.  Use these reagents in a hood
          whenever possible and if eye or skin contact occurs,  flush with
          large volumes of water.  Always wear safety glasses or a shield for
          eye protection when working with these reagents.

6.   APPARATUS AND EQUIPMENT

     6.1  LABWARE - For determination of trace levels of elements,
          contamination and loss are of prime consideration.  Potential
          contamination sources include improperly cleaned laboratory
          apparatus and general contamination within the laboratory
          environment from dust, etc.  A clean laboratory work area designated
          for trace element sample handling must be used.  Sample containers
          can introduce positive and negative errors in the determination of
          trace elements by contributing contaminants through surface
          desorption/leaching, or depleting element concentrations through
          adsorption processes.  All reusable labware (glass, quartz,
          polyethylene, Teflon, etc.), including the sample container, should
          be cleaned prior to use or shown to be contaminant free.  Labware
          should be soaked overnight and thoroughly washed with laboratory-
          grade detergent and water, rinsed with water, and soaked for four
          hours in a mixture of dilute nitric and hydrochloric acid (1+2+9),
          followed by rinsing with water, ASTM type I water and oven drying.

          NOTE:  Chromic acid must not be used for cleaning glassware.

          6.1.1  Glassware - Volumetric flasks, graduated cylinders and  125-mL
                 Erlenmeyer flasks.

          6.1.2  Assorted calibrated pipettes.

          6.1.3  Wash bottle - One piece stem, Teflon FEP bottle with Tefzel
                 ETFE screw closure, 125-mL capacity.

     6.2  SAMPLE PROCESSING EQUIPMENT

          6.2.1  Balance - Analytical, capable of accurately weighing to
                 0.1 mg.

          6.2.2  Hot Plate - (Corning PC100 or equivalent).  An oscillating
                 hot plate will aid in sample digestion.

     6.3  TISSUE DISSECTING EQUIPMENT

          6.3.1. Dissecting Board: Polyethylene or other inert, nonmetallic
                 material, any non-wetting, easy-to-clean or disposable
                 surface is suitable.  Adhesive backed Teflon or plastic
                 film may be convenient to use.

          6.3.2  Forceps:  Plastic, Teflon or Teflon coated.
                                      26

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          6.3.3  Surgical  Blades: Disposable stainless steel  with stainless
                 steel  or plastic handle (Sect. 4.1).

          6.3.4  Scissors:  Stainless steel.

          6.3.5  Plastic bags with watertight seal, metal free.

          6.3.6  Label  tape:  Self-adhesive, vinyl coated marking tape,
                 solvent resistant, usable for temperatures from +121°C
                 to -23°C.

          6.3.7  Polyvinyl chloride or rubber gloves,  talc-free.

7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1  Reagents may contain elemental impurities which might affect
          analytical data.  High-purity reagents should be used whenever
          possible.  All acids used for this method must be of ultra high-
          purity grade.

          7.1.1  Nitric acid, concentrated  (sp.gr. 1.41).

          7.1.2  Hydrochloric acid, concentrated (sp.gr. 1.19).

          7.1.3  Hydrogen peroxide (30%)

     7.2  WATER - For all sample preparation and dilutions, ASTM type  I water
          (ASTM D1193) is required.  Suitable water may be prepared by passing
          distilled water through a mixed bed of anion and cation exchange
          resins.

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  Appropriate individual tissue samples should be taken soon after
          collection and must be taken prior to freezing .   If  dissection of
          the tissue cannot be performed immediately after collection, it
          should be placed  in a plastic bag  (Sect. 6.3.5), sealed and  placed
          on ice or refrigerated at approximately 4°C.

     8.2  Prior to dissection, the tissue should be rinsed with metal-free
          water and blotted dry.  Dissection should be performed within
          24 hours of collection.  Each individual tissue sample should also
          be rinsed with metal-free water,  blotted dry, and frozen at  <-20°C
          (dry ice).

     8.3  Tissue samples  of up to 5 g should be taken using a  special
          implement (Sect.  4.1)  and handled with plastic forceps
          (Sect. 6.S.2)3'4.

     8.4  A maximum holding time for frozen  samples has not been determined.
                                      27

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9.   CALIBRATION AND STANDARDIZATION

     9.1  Not applicable.  Follow instructions given in the analytical method
          selected.

10.  QUALITY CONTROL

     10.1 Each laboratory determining total recoverable elements is required
          to operate a formal quality control (QC) program.  The minimum
          requirements of a QC program consist of an initial demonstration of
          laboratory capability and analysis of laboratory reagent blanks and
          fortified blanks and samples as a continuing check on performance.
          The laboratory is required to maintain performance records that
          define the quality of data generated.

     10.2 Specific instructions on accomplishing the described aspects of the
          QC program are discussed in the analytical methods.

11.  PROCEDURE

     11.1 Sample Preparation - Place up to a 5 g subsample of frozen tissue
          into a 125-mL erlenmeyer flask.  Any sample spiking  solutions should
          be added at this time and allowed to be in contact with the sample
          prior to addition of acid.

     11.2 Add 10 ml of concentrated nitric acid  and warm on a  hot plate until
          the tissue is solubilized.  Gentle swirling the samples or use of an
          oscillating hot plate will aid in this process.

     11.3 Increase temperature to near boiling until  the solution begins to
          turn brown.   Cool  sample,  add an additional  5 ml of  concentrated
          nitric acid and return to the hot plate until the solution once
          again  begins  to turn brown.

     11.4 Cool  sample,  add an additional  2 ml of concentrated  nitric acid,
          return to the hot plate and  reduce the volume to 5-10 mL.   Cool
          sample,  add 2 mL of 30% hydrogen peroxide,  return sample  to the hot
          plate  and reduce the volume  to 5-10 mL.

     11.5 Repeat Sect.  11.4 until  the  solution is  clear or until  a  total  of
          10 mL  of peroxide has been added.   NOTE:  A laboratory reagent blank
          is especially critical  in  this  procedure because the procedure
          concentrates  any reagent  contaminants.

     11.6 Cool the sample,  add 2  mL  of concentrated  hydrochloric  acid,  return
          to the hot  plate and reduce  the volume to  5 mL.
     11
.7 Allow the sample to cool  and quantitatively transfer to a 100-mL
   volumetric flask.   Dilute to volume with  ASTM type I water,  mix,  and
   allow any insoluble material  to separate.   The sample is now ready
   for analysis by either ICP-AES or STGFAA.   For analysis by ICP-MS an
   additional  dilution (1+4) is required.

                               28

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     11.8 Sample Analysis - Use one of the analytical  methods listed in
          Sect.  1.3.

12.   CALCULATIONS

     12.1 Not applicable.  Discussed in analytical  methods listed in Sect.
          1.3.

13.   PRECISION AND ACCURACY

     13.1 Not applicable.  Available data included  in  analytical  methods
          listed in Sect. 1.3.

14.   REFERENCES

     1.   Versieck, J., and F.  Barbier, "Sample Contamination as  A Source of
          Error in Trace-Element Analysis of Biological  Samples," Talanta.
          Vol. 29, pp. 973-984, 1982.

     2.   Ney, J. J., and M. G. Martin, "Influences of Prefreezing on Heavy
          Metal  Concentrations  in Bluegill Sunfish," Water Res..  Vol. 19,
          No. 7, pp.  905-907, 1985.

     3.   "The Pilot National Environmental  Specimen Bank," NBS  Special
          Publication 656, U. S. Department of Commerce,  August,  1983.

     4.   Koirtyohann, S. R., and H. C. Hopps, "Sample Selection, Collection,
          Preservation and Storage for Data Bank on Trace Elements in Human
          Tissue," Federation Proceedings, Vol. 40, No.  8, June,  1981.
                                      29

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                            METHOD  200.7

         DETERMINATION OF METALS AND TRACE ELEMENTS IN WATER
AND WASTES BY INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROMETRY
      Theodore D. Martin, Carol A. Brockhoff and John T. Creed
                      Inorganic Chemistry Branch
                     Chemistry Research Division

                                 and

                           Stephen E. Long
                    Technology Applications, Inc.
                             Revision 3.3
                              April 1991
             ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
                  OFFICE OF RESEARCH AND DEVELOPMENT
                U. S. ENVIRONMENTAL  PROTECTION AGENCY
                        CINCINNATI, OHIO  45268

                                  31

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                            METHOD 200.7

             DETERMINATION OF METALS AND TRACE ELEMENTS
     BY  INDUCTIVELY  COUPLED PLASMA-ATOMIC  EMISSION SPECTROMETRY
1.2
1.   SCOPE AND APPLICATION

     1.1  This method provides procedures for determination of dissolved
          elements in ground waters, surface waters, and drinking water
          supplies.  It may also be used for determination of total
          recoverable element concentrations in these waters and wastewaters
          and, with the exception of silica, in sediments, sludges and solid
          waste samples.

          Dissolved elements are determined after suitable filtration and acid
          preservation.   Acid digestion procedures are required prior to the
          determination  of total  recoverable elements.  To reduce potential
          interferences, dissolved solids should be < 0.2% (w/v)
          (Sect.  4.1.2).                                   v '  ''

          Estuarine water may be  analyzed by this method,  however,  matrix
          matched standards or the method of standard addition  (Sect. 9.8)
          must be used  following  sample preparation (Sect.  11.2.2).   Prepared
          samples may require dilution  prior to analysis to avoid physical
          interferences  (Sect.  4.1.2)  and problematic operation of the sample
          introduction system.

     1.4   This method is applicable to  the  following analytes:
1.3
        Analvte

       Aluminum
       Antimony
       Arsenic
       Barium
       Beryl 1i urn
       Boron
       Cadmium
       Calcium
       Chromium
       Cobalt
       Copper
       Iron
       Lead
       Lithium
       Magnesium
       Manganese
       Mercury
       Molybdenum
       Nickel
                                     Chemical  Abstract Services
                                     Registry  Numbers  fCASRN)
                         (Al)
                         (Sb)
                         (As)
                         (Ba)
                         (Be)
                         (B)
                         (Cd)
                         (Ca)
                         (Cr)
                         (Co)
                         (Cu)
                         (Fe)
                         (Pb)
                         (Li)
                         (Mg)
                         (Mn)
                         (Hg)
                         (Mo)
                         (Ni)
7429-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7440-
7439-
7439-
7439-
7439-
7439-
7439-
7439-
7440-
-90-5
-36-0
-38-2
-39-3
-41-7
•42-8
•43-9
•70-2
•47-3
•48-4
50-8
89-6
92-1
93-1
95-4
96-5
97-6
98-7
02-0
                                32

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       Phosphorus
       Potassium
       Selenium
       Silica
       Silver
       Sodium
       Strontium
       Thallium
       Tin
       Vanadium
       Zinc
(P)
(K)
(Se)
(Si02)
(Ag)
(Na)
(Sr)
(Tl)
(Sn)
(V)
(Zn)
7723-14-0
7440-09-7
7782-49-2
7631-86-9
7440-22-4
7440-23-5
7440-24-6
7440-28-0
7440-31-5
7440-62-2
7440-66-6
     Listed in Table 1 are the recommended wavelengths for these analytes
     along with adjacent locations for background correction.   Also
     listed in Table 1 are typical instrument detection limits (IDLs
     Sect. 3.3) determined using reagent acid ASTM type I water and
     conventional  pneumatic nebulization sample introduction into the
     plasma.   These IDLs are intended as a guide and may vary  for each
     laboratory depending on instrumentation and selected operating
     conditions.  Wavelengths and background correction locations other
     than those recommended may be substituted if they provide the needed
     sensitivity and are properly corrected for interelement spectral
     interferences.

1.5  Specific instrumental operating conditions are given in Table 4.
     However, because of the differences between various makes and models
     of spectrometers, the analyst should follow the instrument
     manufacturer's instructions and if possible, approximate  the
     recommended conditions given (Table 4).

1.6  When using this method for determination of boron and silica in
     aqueous  samples, only plastic,  Teflon or quartz labware should be
     used from time of sample collection to completion of analysis.  For
     accurate determinations of boron in solid sample extracts at
     concentrations below 100 mg/kg, only quartz beakers should be used
     in the digestion with immediate transfer of an extract aliquot to a
     plastic  centrifuge tube following dilution of the digestate to
     volume.   For these determinations,  borosilicate glass must not be
     used in  order to avoid sample contamination of these analytes from
     the glass.

1.7  This method is applicable to analysis of drinking water for the
     determination of primary and secondary contaminant metals.  However,
     it can only be used for compliance monitoring of a drinking water
     contaminant when listed in the Federal Register as an approved
     method and laboratory performance data meet the required  method
     detection limit (MDL) or practical  quantification limit (PQL)
     established by the Office of Ground Water and Drinking Water.  All
     drinking water samples must be pretreated with acid prior to
     analysis.  When pneumatic nebulization is used for these
     determinations, certain analytes require 4X preconcentration prior
     to analysis instead of the 2X preconcentration procedure  given in
                                 33

-------
          Sect. 11.2.1 of this method.  Analytes requiring 4X preconcentration
          are noted in the Federal Register at the time the method is
          promulgated.

     1.8  This method is suitable for determination of silver in aqueous
          samples containing concentrations up to 0.1 mg/L.  For the analysis
          of wastewater samples containing higher concentrations of silver,
          succeeding smaller volume, well mixed aliquots should be prepared
          until the analysis solution contains < 0.1 mg/L silver.

     1.9  The sample preparation procedures given in Sects. 11.2 and 11.3 will
          solubilize and hold in solution only minimal concentrations of
          barium, as barium sulfate.  In addition, the stability of
          solubilized barium is greatly affected when free sulfate is
          available in solution.  The concentration of barium that will remain
          in solution decreases as the free sulfate concentration increases.
          [For example, when a 100 ml aliquot of drinking water containing
          60 mg/L sulfate was fortified with 5 mg of BaS04 salt  (equivalent to
          59 mg/L Ba in the 2X analysis solution) only 33 mg/L Ba was
          initially solubilized using the procedure given Sect.  11.2.1.  Upon
          standing one week, the barium concentration decreased to 12 mg/L.
          When 100 mL of deionized distilled water was fortified, the entire
          5 mg of BaSO, was  solubilized and remained in solution over the same
          time period.]  For more accurate determinations of barium in samples
          having varying and unknown concentrations of sulfate,  samples should
          be analyzed as soon as possible after sample preparation is
          completed.

     1.10 With the exception of estuarine waters, once the samples have been
          collected, approximately 20 samples including the mandatory quality
          control samples can be analyzed using this method during a 1.5 work
          day period.

2.   SUMMARY OF METHOD

     2.1  This method describes a technique for simultaneous or sequential
          multielement determination of metals and trace elements in solution.
          The basis of the method is the measurement of atomic emission by an
          optical spectrometric technique.  Samples are nebulized and the
          aerosol that is produced is transported to the plasma torch where
          desolyation and excitation occur.  Characteristic atomic-line
          emission spectra are produced by a radio-frequency inductively
          coupled plasma (ICP).   The spectra are dispersed by a grating
          spectrometer, and line intensities are monitored by a photosensitive
          device (e.g. photomultiplier tube or diode array).  Photocurrents
          from the photosensitive device are processed and controlled by a
          computer system.  A background correction technique is required to
          compensate for variable background contribution to the determination
          of the analytes.  Background must be measured adjacent to analyte
          lines on samples during analysis.  The position selected for the
          background intensity measurement, on either or both sides of the
          analytical line, will  be determined by the complexity of the

                                      34

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          spectrum adjacent to the analyte line.   The position used must
          either be free of spectral  interference or adequately corrected to
          reflect the same change in  background intensity as occurs at the
          analyte wavelength  measured.  Background correction is not required
          in cases of line broadening where a background correction
          measurement would actually  degrade the analytical result.  The
          possibility of additional  interferences named in Sect. 4.1 (and
          tests for their presence as described in Sect. 4.2) should also be
          recognized and appropriate  corrections made.

3.   DEFINITIONS

     3.1  DISSOLVED - The concentration of analyte that will pass through a
          0.45-/im membrane filter  assembly, prior to  sample acidification.

     3.2  TOTAL RECOVERABLE - The concentration of an analyte determined in an
          unfiltered sample following treatment by refluxing with hot, dilute
          mineral acid.

     3.3  INSTRUMENTAL DETECTION LIMIT (IDL) - The concentration equivalent to
          the analyte signal which is equal to three times the  standard
          deviation of a series of ten replicate measurements of a reagent
          blank signal at the same wavelength.

     3.4  METHOD DETECTION LIMIT (MDL) - The minimum concentration of an
          analyte that can be identified, measured and reported with 99%
          confidence that the analyte concentration is greater than zero
          (Sect. 10.2.2).

     3.5  LINEAR DYNAMIC RANGE (LDR)  - The concentration range over which the
          analytical curve remains linear (Sect. 10.2.3).

     3.6  METHOD OF STANDARD ADDITION - The standard  addition technique
          involves the use of the  unknown and the unknown plus a known amount
          of standard  (Sect. 9.8.1).

     3.7  LABORATORY REAGENT BLANK (LRB)  (preparation blank) - An aliquot of
          reagent water that is treated exactly as a  sample including exposure
          to all glassware, equipment, reagents, and  acids that are used with
          other samples.  The LRB  is used to determine if method analytes or
          other interferences are  present in the laboratory environment, the
          reagents or  apparatus (Sects. 7.5.2 and 10.3.1).

     3.8  CALIBRATION  BLANK - A volume of ASTM type I water acidified with the
          same acid matrix as in the calibration standards.  The calibration
          blank is a zero standard and is used to calibrate the  ICP instrument
          (Sect. 7.5.1).

     3.9  STOCK STANDARD SOLUTION  - A concentrated solution containing one
          analyte prepared in the  laboratory using assayed reference materials
          or purchased from a reputable commercial source  (Sect. 7.3).  Stock


                                      35

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      standard solutions are used to prepare calibration  solutions  and
      other needed analyte solutions.

 3.10 CALIBRATION STANDARD (CAL)  - A solution prepared from the  dilution
      of stock standard solutions.  The CAL solutions  are used to
      calibrate the instrument response with respect to analyte
      concentration (Sect. 7.4).

 3.11 LABORATORY PERFORMANCE CHECK SOLUTION (LPC)  - A  solution of method
      analytes,  used to evaluate  the performance  of the instrument  system
      with respect to a defined set of method criteria (Sects. 7.8  and
      9.6).

 3.12 PLASMA SOLUTION - A solution that is  used to determine the optimum
      height above the work coil  for viewing the  plasma (Sects.  7.6 and
      9.3.3).

 3.13 TUNING SOLUTION - A solution which is used  to determine acceptable
      instrument performance prior to  calibration  and  sample analyses
      (Sects.  7.7 and 9.4).

 3.14 SPECTRAL INTERFERENCE CHECK SOLUTION  (SIC)  - A solution of selected
      method analytes of higher level  concentrations which  is used  to
      evaluate the procedural  routine  for correcting known  interelement
      spectral  interferences with respect to a defined  set  of method
      criteria (Sects.  7.9 and 9.7).

 3.15 LABORATORY FORTIFIED BLANK  (LFB)  - An  aliquot of  reagent water to
      which  known quantities of the  method  analytes are added in the
      laboratory.   The  LFB is  analyzed  exactly like a  sample, and its
      purpose  is to determine  whether method  performance  is  within
      acceptable control  limits (Sects.  7.11  and  10.3.2).

 3.16  LABORATORY FORTIFIED SAMPLE MATRIX (LFM) - An aliquot  of an
      environmental  sample to  which  known quantities of the  method
      analytes are  added  in  the laboratory.   The LFM is analyzed exactly
      like a sample,  and  its purpose is to determine whether  the sample
      matrix contributes  bias  to  the analytical results.  The background
      concentrations  of the  analytes in the  sample matrix must be
      determined  in  a separate  aliquot  and the measured values in the LFM
      corrected  for  the concentrations  found  (Sect. 10.4).

3.17  FIELD DUPLICATES  (FD1 AND FD2) - Two separate samples collected at
      the same time  and place  under  identical circumstances  and treated
      exactly the same throughout  field and laboratory procedures.
     Analyses of FD1 and  FD2 give a measure of the precision associated
     with sample collection, preservation,  and storage, as well  as with
      laboratory procedure.

3.18 QUALITY CONTROL SAMPLE (QCS) - A solution of method  analytes  of
      known concentrations which  is used to fortify an  aliquot of LRB
     matrix.  The QCS is obtained from a source external  to the

                                 36

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          laboratory, and is used to check laboratory performance (Sects. 7.12
          and 10.2.4).

4.   INTERFERENCES

     4.1  Several types of interference effects may contribute to inaccuracies
          in the determination of an analyte by ICP-AES.  They can be
          summarized as follows:

          4.1.1  Spectral interferences - Can be categorized as (1) overlap of
                 a spectral line from another element; (2) unresolved overlap
                 of molecular band spectra; (3) background contribution from
                 continuous or recombination phenomena; and (4) background
                 contribution from stray light from the line emission of high
                 concentration elements.1  The first of these effects can be
                 compensated by utilizing a computer correction of raw data,
                 requiring monitoring and measurement of the interfering
                 element. -3  The second  effect may require selection of  an
                 alternative wavelength.  The third and fourth effects can
                 usually be compensated  by a background correction adjacent to
                 the analyte line.

                 Given in Table 3 is a listing of the interelement spectral
                 interferences that can  occur between method analytes when
                 using the recommended wavelengths and locations for back-
                 ground corrections listed in Table 1.  Table 3 is not a
                 complete listing of all possible interelement interferences;
                 however, those not included are interferences from elements
                 either not readily solubilized by the sample preparation
                 procedures described in this method or from elements rare  in
                 nature.  The correction factors listed in Table 3 indicate
                 the magnitude of the interference.  The factors were
                 experimentally determined at EMSL-Cincinnati using an
                 instrument with a specified wavelength dispersion of 0.53
                 nm/mm and a spectral bandpass resolution of 0.036 nm in the
                 first order.  The factors have been rounded to the tenth-
                 thousand place or reported to one significant number.   The
                 listing is presented as a guide for users of this method for
                 determining interelement  interference effects.  The reader is
                 cautioned that other analytical systems may exhibit somewhat
                 different levels of interference than those shown in Table 3
                 and  that the interference effects must be evaluated for each
                 individual instrumental system.

                 The  correction factors  given in Table 3 were determined by
                 analyzing single element  solutions of each  interfering
                 element.  The concentration of each single  element  solution
                 was  within the LDR of that element.  For most elements  a
                 100  mg/L  solution was used with the numerical value of  most
                 correction factors being  confirmed by analyzing lesser
                 dilutions of the single element solution.   Because  Ca,  Fe, Mg
                 and  Na  can normally be  present at concentrations  in excess of

                                      37

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4.1.2
 100 mg/L,  the interferences  attributed  to  these elements  were
 determined at concentrations near their linear limits.  The
 criteria for listing a spectral  interference  was an  apparent
 analyte concentration from the  interfering single element
 solution that was  outside  the 95% confidence  interval
 estimates  for the  determined MDL limits4 of the  analyte using
 the 2x preconcentration procedure described in Sect.  11.2.1
 (See Table 2).   The  correction  factor was  calculated  by
 dividing the blank subtracted apparent  analyte concentration
 by  the determined  concentration  of the  interfering element.

 Positive values  in Table 3 are  interferences  that occur on
 the wavelength peaks,  while  negative values indicate  an
 interference at  the  location used for background correction.
 In  practice,  during  analysis, the correction  factor  is used
 to  calculate the apparent  concentration from  interfering
 element and is then  subtracted  from the instrumental  analyte
 concentration to determine the  net, or  sample analyte
 concentration (while positive values are subtracted,  negative
 values are actually  added).   Without these corrections when
 interference effects are present,  either false positive or
 false negative determinations will  result.  Also,  the
 reliability of an  applied  correction depends  on  the variance
 surrounding the  measurement  of the  interfering element.   As
 the concentration  of the interfering element  increases, the
 variance increases;  this is  reflected in the  calculated
 apparent analyte concentration.   Extreme caution  should be
 exercised  when reporting analyte  concentrations  where the
 apparent analyte concentration from an  interfering element
 accounts for 90% of  the  measured  analyte concentration.   Once
 a routine  procedure  for  correcting  interelement  spectral
 interferences has  been  established, it  should  be  periodically
 tested  to  evaluate its  operational effectiveness  and
 continued  reliability  (Sect.  7.9).

 Physical interferences  - Are  generally  considered to be
 effects  associated with  the  sample nebulization  and
 transport  processes.   Such properties as change  in viscosity
 and  surface  tension  can  cause significant  inaccuracies
 especially  in samples which may contain high dissolved solids
 and/or  high  acid concentrations.  The use  of a peristaltic
 pump may lessen  these interferences.  If these types of
 interferences are operative,  they must  be  reduced by sample
 dilution and/or  utilization of standard addition techniques
 (Sect.  9.8).  Another problem which can occur  from high
 dissolved solids is  salt buildup at the tip of the nebulizer.
 This affects aerosol  flow rate causing  instrumental drift.
 Wetting  the argon prior to nebulization, use of a tip washer,
 or sample dilution have been used to control this problem.
Also, it has been reported that better control of the argon
 flow rate improves instrument performance.   This is
 accomplished with the use of mass flow controllers.
                            38

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     4.1.3  Chemical Interferences - Are characterized by molecular
            compound formation, ionization effects and solute vaporiza-
            tion effects.  Normally these effects are not pronounced
            with the ICP technique, however, if observed they can be
            minimized by careful selection of operating conditions (i.e.,
            incident power, observation position, etc.), by buffering the
            sample, matrix matching, or standard addition procedures.
            These types of interferences can be highly dependent on
            matrix type and the specific analyte element.

     4.1.4  Memory interferences - Result when analytes in a previous
            sample contribute to the signals measured in a current
          ;:  sample.  Memory effects can result from sample deposition on
            the uptake tubing to the nebulizer or from build-up of sample
            material in the plasma torch and spray chamber.  The site
            where these effects occur is dependent on the element and can
            be minimized by flushing the system with a rinse blank
            between samples (Sect. 7.5.3).  The possibility of memory
            interferences should be  recognized within an analytical run
            and suitable rinse times should be used to reduce them.  The
            rinse times necessary for a particular element should be
            estimated prior to analysis.  This may be achieved by
            aspirating a standard containing elements corresponding to
            either their LDRs or concentrations ten times those usually
            encountered.  The aspiration time should be the same as a
            normal sample analysis period, followed by analysis of the
            rinse blank at designated intervals.  The length of time
            required to reduce analyte signals to within a factor of two
            of the method detection limit should be noted.  Until the
            required rinse time is established, this method recommends a
            rinse period of 60 sec between samples and standards.  If a
            memory interference is suspected, the sample should be
            reanalyzed after a long rinse period.

4.2  The occurrence of interferences described in Sects. 4.1.1, 4.1.2 and
     4.1.3 are primarily attributed to the sample matrix.  If an
     interference caused by a particular sample matrix is known, in many
     cases it can be circumvented.  However, when the nature of the
     sample is unknown, tests as outlined in Sects. 4.2.1 through 4.2.4
     can be used to ensure the analyst that neither positive nor negative
     interference effects are operative on any of the analyte elements
     thereby distorting the accuracy of the reported values.

     4.2.1  Serial dilution - If the analyte concentration is
            sufficiently high (minimally a factor of 10X the MDL after
            dilution), an analysis of a dilution should agree within 10%
            of the original determination or within an established
            acceptable control limit.5  If not,  a chemical  or physical
            interference effect should be suspected.

     4.2.2  Analyte addition - A post digestion analyte addition added at
            a minimum level of 20X the MDL (maximum 100X) to the original

                                 39

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                 determination should be recovered to within 90% to 110% or
                 within an established control limit.  If not, a matrix effect
                 should be suspected.  The use of a standard addition analysis
                 procedure can usually compensate for this effect.  CAUTION:
                 The standard addition technique does not detect coincident
                 spectral overlap.  If suspected, use of computerized
                 compensation, an alternative wavelength, or comparison with
                 an alternative method is recommended (Sect. 4.2.3).

          4.2.3  Comparison with alternative method of analysis - When
                 investigating a sample matrix, comparison tests may be
                 performed with other analytical techniques, such as atomic
                 absorption spectrometry, ICP-mass spectrometry, or other
                 approved methodology.

          4.2.4  Wavelength scanning of analyte line region - If the appro-
                 priate equipment is available, wavelength scanning can be
                 performed to detect potential spectral  interferences.

5.   SAFETY

     5.1  The toxicity or carcinogenicity of each reagent used in this method
          has not been fully established.  Each chemical should be regarded as
          a potential health hazard, and exposure to these compounds should be
          as low as reasonably achievable.  Each laboratory is responsible for
          maintaining a current file of OSHA regulations regarding the safe
          handling of chemicals specified in this method 6"9.  A reference
          file of material data handling sheets should also be made available
          to all personnel involved in the chemical analysis.  Specifically,
          concentrated nitric and hydrochloric acids are moderately toxic and
          extremely irritating to skin and mucus membranes.  Use these
          reagents in a hood whenever possible and if eye or skin contact
          occurs, flush with large volumes of water.  Always wear safety
          glasses or a shield for eye protection when working with these
          reagents.

     5.2  Analytical plasma sources emit radiofrequency radiation and intense
          UV radiation.  Suitable precautions should be taken to protect
          personnel from such hazards.

     5.3  All personnel handling environmental samples known to contain or to
          have been in contact with human waste should be immunized against
          known disease causative agents.

     5.4  Precautions should also be taken to minimize potential hazards.
          Basic good housekeeping and safety practices such as the use of
          rubber or plastic gloves and safety glasses during cleaning of
          labware are highly recommended.

6.   APPARATUS AND EQUIPMENT

     6.1  ANALYTICAL INSTRUMENTATION

                                      40

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     6.1.1  The ICP instrument may be a simultaneous or sequential
            spectrometer system that uses ionized argon gas as the
            plasma.  However,  the system and processing of background
            corrected signals  must be computer controlled.  The
            instrument must be capable of meeting and complying with the
            requirements and description of the technique given in  Sect.
            2.1 of the method.  In particular, it is the responsibility
            of the analyst to  investigate the spectral  interference
            (Sect. 4.1.1) operative about each analytical wavelength used
            and to verify and  periodically confirm that the instrument
            configuration and  operating conditions used satisfy the
            analytical requirements.

     6.1.2  Argon gas supply - Liquid, high purity grade (99.99%).

     6.1.3  A variable speed peristaltic pump is required to deliver both
            standard and sample solutions to the nebulizer.

     6.1.4  Mass flow controllers to regulate the argon flow rates,
            especially the aerosol transport gas, are highly recommended.
            Their use will provide more exacting control of reproducible
            plasma conditions.

     6.1.5  For routine analyses of solutions containing dissolved  solids
            >1%, a high solids nebulizer and a torch injector tube  having
            an i.d. >1.0 mm are recommended. (Consult the instrument
            manufacturer for guidance.)

     6.1.6  For sustained analyses of solutions containing alkali
            concentrations >0.5%, an alumina torch injector tube is
            recommended to prevent devitrification of the normally-used
            quartz injector tube.

            NOTE: Regular periodic cleaning of the quartz torch assembly
            and injector tube  by soaking in aqua regia (Sect. 7.1.9)
            reduces background signal noise, calibration drift and
            potential memory effects.

6.2  SAMPLE PROCESSING EQUIPMENT

     6.2.1  Air Displacement Pipetter:  Digital pipet capable of
            delivering volumes ranging from 0.1 to 2500 #L with an
            assortment of high quality disposable pipet tips.

     6.2.2  Hot Plate:  Ceramic top, graduated dial 90°C to 450°C
            (Corning PC100 or  equivalent).

     6.2.3  Single pan balance:  Balance capable of weighing to the
            nearest 0.01 g.
                                 41

-------
          6.2.4  Analytical balance:  Balance capable of weighing to the
                 nearest 0.0001 g.

          6.2.5  Centrifuge:  Steel cabinet with guard bowl, electric timer
                 and brake.  (International Centrifuge, Universal Model UV or
                 equivalent.)

          6.2.6  Drying oven:  Gravity convection oven, with thermostatic
                 control capable of maintaining 180°C ± 5°C.

     6.3  LABWARE - For the determination of trace levels of elements,
          contamination and loss are of prime consideration.  Potential
          contamination sources include improperly cleaned laboratory
          apparatus and general contamination within the laboratory
          environment from dust, etc.  A clean laboratory work area,
          designated for trace element sample handling must be used.  Sample
          containers can introduce positive and negative errors in the
          determination of trace elements by (1) contributing contaminants
          through surface desorption or leaching, (2) depleting element con-
          centrations through adsorption processes.  All reuseable labware
          (glass, quartz, polyethylene, Teflon, etc.), including the sample
          container, should be cleaned prior to use.  Labware should be soaked
          overnight and thoroughly washed with laboratory-grade detergent and
          water, rinsed with water, and soaked for four hours in a mixture of
          dilute nitric and hydrochloric acid (1+2+9), followed by rinsing
          with water, ASTM type I water, and oven drying.

          NOTE: Chromic acid must not be used for cleaning glassware.

          6.3.1  Glassware - Volumetric flasks, graduated cylinders, funnels
                 and centrifuge tubes (glass and/or metal-free plastic).

          6.3.2  Assorted calibrated pipettes.

          6.3.3  Conical Phillips beakers, 250-mL with 50-mm watch glasses.
                 Griffin beakers, 250-mL with 75-mm watch glasses.  Teflon
                 and/or quartz beakers, 250-mL with Teflon covers (optional).

          6.3.4  Wash bottle - One piece stem, Teflon FEP bottle with Tefzel
                 ETFE screw closure, 125-mL capacity.

7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1  Reagents may contain elemental impurities which might affect
          analytical data.  Only high-purity reagents should be used whenever
          possible.  All acids used for this method must be of ultra high-
          purity grade.  Suitable acids are available from a number of
          manufacturers or may be prepared by sub-boiling distillation.

          7.1.1  Nitric acid, concentrated (sp.gr.  1.41) (CASRN 7697-37-2).
                                      42

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     7.1.2  Nitric acid (1+1) - Add 500 ml cone, nitric acid to 400 ml of
            ASTM type I water and dilute to 1 L.

     7.1.3  Nitric acid (1+9) - Add 100 ml cone, nitric acid to 400 ml of
            ASTM type I water and dilute to 1 L.

     7.1.4  Hydrochloric acid, concentrated (sp.gr. 1.19) (CASRN 7647-01-
            0).

     7.1.5  Hydrochloric acid (1+1) - Add 500 ml cone, hydrochloric acid
            to 400 ml of ASTM type I water and dilute to 1 L

     7.1.6  Hydrochloric acid (1+4) - Add 200 ml cone, hydrochloric acid
            to 400 ml ASTM type I water and dilute to 1 L.

     7.1.7  Ammonium hydroxide, concentrated (sp. gr. 0.902) (CASRN 1336-
            21-6).

     7.1.8  Tartaric acid, ACS reagent grade (CASRN 87-69-4).

     7.1.9  Aqua regia - Add 100 ml cone, nitric acid to 300 ml cone.
            hydrochloric acid and 100 ml ASTM type I water.

7.2  WATER - For all sample preparation and dilutions, ASTM type I water
     (ASTM D1193)   is  required.  Suitable water  maybe  prepared  by
     passing distilled water through a mixed bed of anion and cation
     exchange resins.

7.3  STANDARD STOCK SOLUTIONS - May be purchased from a reputable
     commercial source or prepared from ultra high-purity grade chemicals
     or metals (99.99 - 99.999% pure).  All  salts should be dried for one
     hour at 105°C, unless otherwise specified.  (CAUTION: Many metal
     salts are extremely toxic if inhaled or swallowed.  Wash hands
     thoroughly after handling).  Stock solutions should be stored in
     Teflon bottles.

     The following procedures may be used for preparing standard stock
     solutions:

     NOTE: Some metals, particularly those which form surface oxides
     require cleaning prior to being weighed.  This may be achieved by
     pickling the surface of the metal in acid.  An amount in excess of
     the desired weight should be pickled repeatedly, rinsed with water,
     dried and weighed until the desired weight is achieved.

     7.3.1  Aluminum solution, stock 1 ml = 1000 jug Al: Pickle aluminum
            metal in warm (1+1) hydrochloric acid to an exact weight of
            0.100 g. Dissolve in 10 ml cone, hydrochloric acid and 2 ml
            cone, nitric acid, heating to effect solution.  Continue
            heating until volume is reduced to 4 ml.  Cool and add 4 ml
                                 43

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       ASTM type I water.  Heat until volume is reduced to 2 mL.
       Cool and dilute to 100 mL with ASTM type I water.

7.3.2  Antimony solution, stock 1 mL = 500 /ig Sb: Dissolve 0.100 g
       Sb powder in 2 mL (1+1) nitric acid and 1.0 mL cone.
       hydrochloric acid. Add 10 mL ASTM type I water and 0.15 g
       tartaric acid.  Warm slightly to effect complete solution.
       Cool and dilute to 200 mL with ASTM type I water.

7.3.3  Arsenic solution, stock 1 mL = 1000 p,g As: Dissolve 0.1320 g
       As203  in  a mixture of  50 mL  ASTM type  I water  and 1  mL  cone.
       ammonium hydroxide.   Heat gently to dissolve.   Cool and
       acidify the solution with 2 mL cone, nitric acid.  Dilute to
       100 mL with ASTM type I water.

7.3.4  Barium solution, stock 1 mL = 500 /Ltg Ba: Dissolve 0.1437 g
       BaC03  in  a  solution  mixture of 10  mL ASTM type I water and 5
       mL cone,  nitric acid.   Heat and stir to effect solution and
       degassing.   Dilute to 200 mL with ASTM type I  water.

7.3.5  Beryllium solution,  stock 1 mL = 500 jLig Be: Dissolve 1.965 g
       BeS04.4H20  (DO  NOT DRY)  in  50  mL ASTM Type  I water.  Add  2 mL
       cone,  nitric acid.  Dilute to 200 mL with ASTM type I water.

7.3.6  Boron  solution, stock 1 mL = 1000 fig B:  DO NOT  DRY.
       Dissolve 0.5716 g anhydrous H3B03  in 20 mL  ASTM  type I  water.
       Dilute to 100 mL with ASTM type I water, mix and immediately
       transfer to a Teflon bottle for storage.  Use  a reagent
       meeting ACS specifications, keep the bottle tightly stoppered
       and store in a desiccator to prevent the entrance of
       atmospheric moisture.

7.3.7  Cadmium solution, stock 1 mL = 1000 /itg Cd: Pickle cadmium
       metal  in (1+9) nitric acid to an exact weight  of 0.100 g.
       Dissolve in 5 mL  (1+1) nitric acid, heating to effect
       solution.  Cool and dilute to 100 mL with ASTM type I water.

7.3.8  Calcium solution, stock 1 mL = 1000 p.g Ca: Suspend  0.2498 g
       CaC03  dried  at 180°C for 1 hour before weighing, in 20 mL of
       ASTM type I water.  Dissolve cautiously (reaction is
       vigorous) by adding dropwise,  10 mL (1+1) hydrochloric acid.
       Dilute to 100 mL with ASTM type I water.

7.3.9  Chromium solution, stock 1 mL = 500 /xg Cr: Dissolve 0.1923g
       Cr03 in  a solution mixture of  10 mL ASTM type  I  water and 2
       mL cone, nitric acid.
       water.
Dilute to 200 mL with ASTM type I
7.3.10 Cobalt solution, stock 1 mL = 1000 /ng Co: Pickle cobalt
       metal in (1+9) nitric acid to an exact weight of 0.100 g.
                            44

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        Dissolve in 5 ml (1+1) nitric acid, heating to effect
        solution.   Cool  and dilute to 100 ml with ASTM type I water.

 7.3.11 Copper solution, stock 1 mL = 1000 /zg Cu: Pickle copper
        metal  in (1+9) nitric acid to an exact weight of 0.100 g.
        Dissolve in 5 mL (1+1) nitric acid, heating to effect
        solution.   Cool  and dilute to 100 ml with ASTM type I water.

 7.3.12 Iron solution, stock, 1 ml = 1000 jzg Fe:  Pickle iron metal
        in  (1+1) hydrochloric acid to an exact weight of 0.100 g.
        Dissolve in 10 ml (1+1) hydrochloric acid,  heating to effect
        solution.   Cool  and dilute to 100 mL with ASTM type I water.

 7.3.13 Lead solution, stock 1 mL = 1000 /zg Pb: Dissolve 0.1599 g
        PbN03  in 5  mL  (1+1)  nitric  acid.   Dilute  to  100  mL  with ASTM
        type I water.

 7.3.14 Lithium solution,  stock 1 mL = 500 jug Li: Dissolve 0.5324 g
        Li?C03 in 20 mL ASTM type I water.  Add 2 mL cone, nitric
        acid and dilute  to  200 mL with ASTM type  I  water.

 7.3.15 Magnesium solution,  stock 1 mL = 1000 /zg Mg: Dissolve
        0.100  g  cleanly  polished magnesium ribbon in 5 mL  (1+1)
        hydrochloric  acid.   (Add acid  slowly,  reaction is  vigorous)
        Add  2  mL (1+1) nitric acid  and dilute to  100 mL  with  ASTM
        type I water.

 7.3.16 Manganese solution,  stock 1  mL = 1000 /zg  Mn: Pickle
        manganese flake  in  (1+9)  nitric  acid  to an  exact weight of
        0.100  g.  Dissolve  in  5  mL  (1+1)  nitric acid,  heating  to
        effect solution.  Cool  and  dilute  to  100  mL  with ASTM  type  I
        water.

 7.3.17  Mercury solution, stock  1 mL =  500  /zg Hg: DO NOT DRY,  highly
        toxic, poison.   Dissolve  0.1354  g HgCl, in 20 mL ASTM type I
        water.  Add 10 mL cone,  nitric  acid and dilute to 200 mL with
        ASTM type I water.

 7.3.18  Molybdenum  solution,  stock  1 mL  = 1000 /zg Mo:  Dissolve
        0.1500 g Mo03 in  a solution mixture of 10 mL ASTM type I
       water and 1 mL cone, ammonium  hydroxide, heating to effect
        solution.   Cool  and dilute to  100 mL with ASTM type I water.

7.3.19 Nickel  solution,  stock 1 mL =  1000 /zg Ni: Dissolve  0.100 g
       nickel  powder  in 5 mL cone, nitric acid, heating to effect
        solution.  Cool and dilute to 100 mL with ASTM type I water.

7.3.20 Phosphorus solution, stock 1 mL = 1000 /zg P: Dissolve
       0.3745 g NH4H2P04 in 20 mL ASTM type I water.  Dilute to 100
       mL with ASTM type I water.
                            45

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7.3.21 Potassium solution, stock, 1 ml = 1000 M9 K:  Dissolve
       0.1907 g KC1, previously dried at 110°C for 3 hrs in 20 ml
       ASTM type I water.  Add 2 mL (1+1) hydrochloric acid and
       dilute to 100 ml with ASTM type I water.

7.3.22 Selenium solution, stock 1 ml = 500 jug Se: Dissolve 0.1405 g
       Se02 in 20 ml ASTM type I water.   Dilute to  200 ml with ASTM
       type I water.

7.3.23 Silica solution, stock, 1 ml = 1000 /ug Si02:  Do not dry.
       Dissolve 0.2964 g NH4SiF6 in  20 ml solution  mixture  of  ASTM
       type I water and 1 ml cone, hydrochloric acid, heating at
       85°C for 5 min to effect solution.  Cool, dilute to 100 ml
       with ASTM type I water, mix and immediately transfer to
       Teflon bottle for storage.

7.3.24 Silver solution, stock 1 ml = 250 p.g Ag: Dissolve 0.125 g
       silver metal in 10 ml (1+1) nitric acid, heating to effect
       solution.  Cool and dilute to 500 ml with ASTM type I water.
       Store in amber container.

7.3.25 Sodium solution, stock 1 ml = 1000 p.g Na: Dissolve  0.2542 g
       NaCl in 20 mL ASTM type  I water.  Add 2 ml  (1+1) nitric acid
       and dilute to 100 ml with ASTM type I water.

7.3.26 Strontium solution, stock 1 mL =  500 /ug  Sr: Suspend 0.1685 g
       SrC03 in 20 mL ASTM type I water.  Dissolve continuously by
       adding dropwise 10 mL (1+1) hydrochloric acid.  Dilute to 200
       mL with ASTM type  I water.

7.3.27 Thallium solution, stock  1 mL = 500 jig  Tl:  Dissolve 0.1303 g
       T1N03 in a solution mixture of 10 mL ASTM type I water and 2
       mL cone, nitric acid.  Dilute to  200 mL with ASTM type I
       water.

7.3.28 Tin solution, stock 1 mL = 1000 /jg Sn:  Dissolve 0.100  g  Sn
       shot in 20 mL (1+1) hydrochloric  acid, heating to effect
       solution.  Cool and dilute to 100 mL with (1+1) hydrochloric
       acid.

7.3.29 Vanadium solution, stock  1 ml =  1000 >tg  V:  Pickle  vanadium
       metal  in  (1+9) nitric acid to an  exact weight of 0.100 g.
       Dissolve in  5 mL  (1+1) nitric acid, heating to effect
       solution.  Cool and dilute to 100 mL with ASTM type I water.

7.3.30 Yttrium solution,  stock  1 mL = 1000 /jg Y: Dissolve  0.1270 g
       Y20, in 5 mL (1+1) nitric acid,  heating  to effect  solution.
       Cool and dilute to 1000  mL with ASTM type I water.

7.3.31 Zinc solution, stock 1 mL =  500 jitg Zn:  Pickle  zinc metal  in
       (1+9)  nitric acid  to an  exact weight of  0.100 g.   Dissolve  in

                            46

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            10 ml (1+1) nitric acid, heating to effect solution.
            and dilute to 200 ml with ASTM type I water.
                                        Cool
7.4  MIXED CALIBRATION STANDARD (CAL) SOLUTIONS—Prepare mixed CAL
     solutions (Sects. 7.4.1 thru 7.4.5) by combining appropriate volumes
     of the stock standard solutions in 500-mL volumetric flasks.
     First, add 20 mL of (1+1) nitric acid and 20 mL of (1+1)
     hydrochloric acid,  then add the appropriate stock standard aliquots
     and dilute to 500 mL with ASTM type I water.  Prior to preparing the
     mixed CAL solutions, each stock solution should be analyzed
     separately to determine the presence of impurities.  Transfer the
     freshly prepared mixed CAL solutions to an acid clean, not
     previously used FEP fluorocarbon or polyethylene bottles for
     storage.   Fresh mixed CAL solutions should be prepared as needed
     with the realization that concentration can change on aging.  The
     CAL solutions must  be initially verified using a quality control
     sample and monitored weekly for stability (Sect. 7.12).   Although
     not specifically required, the listed CAL solution combinations
     should be followed  when using the specific wavelengths and
     recommended background correction locations listed in Table 1.   If
     different combinations are used,  the mixture should be verified for
     compatibility,  stability and absence of spectral interference
     between analytes.  This same requirement would apply if different
     wavelengths and/or  background correction locations are utilized.

     7.4.1  CAL Solution I (Volume = 500.0 mL)
            Analvte

              Ag
              As
              B
              Ba
              Ca
              Cd
              Cu
              Mn
              Sb
              Se
 Stock
Solution

 7.3.24
 7.3.3
 7.3.6
 7.3.4
 7.3.8
 7.3.7
 7.3.11
 7.3.16
 7.3.2
 7.3.22
Aliquot
Vol. mL

  1.0
  5.0
  1.0
  1.0
  5.0
  1.0
  1.0
  1.0
  5.0
  5.0
  Analyte
Cone. uq/mL

    0.5
   10.0
    2.0
    1.0
   10.0
    2.0
    2.0
    2.0
    5.0
    5.0
             NOTE:   If  the  addition of  silver to the recommended
             acid combination  results in an  initial precipitation, add
             15 mL  of ASTM  type  I water and  warm the flask until the
             solution clears.  For the  acid  concentration used  in the
             CAL solutions, the  silver  concentration should be  limited
             to 0.5 mg/L.   Higher concentrations of silver require
             additional hydrochloric acid.
                                47

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    7.4.2  CAL Solution  II  (Volume = 500.0 ml)
           Analvte

             K
             Li
             Mo
             Na
             Sr
 Stock
Solution
 7.3.21
 7.3.14
    ,18
    .25
7.3.
7.3,
 7.3.26
Aliquot
Vol. ml

 10.0
  5.0
  5.0
  5.0
  1.0
  Analyte
Cone, uq/ml

   20.0
    5.0
   10.0
   10.0
    1.0
     7.4.3   CAL  Solution  III  (Volume  =  500.0 mL)
                                        Aliquot
                                        Vol. mL

                                           1.0
                                           1.0
                                           5.0
                                      500.0  mL)

                                         Aliquot
                                         Vol.  mL

                                          5.0
                                          5.0
                                          2.0
                                          5.0
                                          2.0
                                          5.0
Analvte
Co
V
P
7.4.4 CAL Solution
Analvte
Al
Cr
Hg
Si02
Sn
Zn
">Stock
Solution
7.3.10
7.3.29
7.3.20
IV (Volume
Stock
Solution
7.3.1
7.3.9
7.3.17
7.3.23
7.3.28
7.3.31
                               Analyte
                             Cone. uq/mL

                                 2.0
                                 2.0
                                10.0
                               Analyte
                             Cone. uq/mL

                                10.0
                                 5.0
                                 2.0
                                10.0
                                 4.0
                                 5.0
     7.4.5  CAL Solution V (Volume = 500.0 mL)
            Analvte

              Be
              Fe
              Mg
              Ni
              Pb
              Tl
  Stock
 Solution

  7.3.5
  7.3.12
  7.3.15
  7.3.19
  7.3.13
  7.3.27
              Aliquot
              Vol. mL
                  ,0
                  .0
                  ,0
                  .0
                5.0
                5.0
                 Analyte
               Cone.  uq/mL

                   1.0
                  10.0
                  10.0
                   2.0
                  10.0
                   5.0
7.5  BLANKS - Three types of blanks are required for this method.  A
     calibration blank is used to establish the analytical calibration
     curve, a laboratory reagent blank is used to assess possible
     contamination from the sample preparation procedure and a rinse
                                 48

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     blank is used to flush the instrument uptake system and nebulizer
     between standards and samples to reduce memory interferences.

     7.5.1  Calibration blank - Prepare by diluting a mixture of 20 ml of
            (1+1) nitric acid and 20 ml of (1+1) hydrochloric acid to 500
            ml with ASTM type I water.  Store in a Teflon bottle.

     7.5.2  Laboratory reagent blank (LRB) - Contains all the reagents in
            the same volumes used in processing the samples.  The LRB
            must be carried through the entire preparation procedure and
            analysis scheme.  The final solution should contain the same
            acid concentrations as sample solutions for analysis.

     7.5.3  Rinse blank - Prepare this acid wash solution in the same
            manner as the calibration blank and store in a convenient
            manner.

7.6  PLASMA SOLUTION - This solution is used for determining the optimum
     viewing height of the plasma above the work coil  prior to using the
     method (Sect. 9.3.3).  The solution is prepared by adding a 5 mL
     aliquot from each of the stock standard solutions of arsenic
     (Sect. 7.3.3) and lead (Sect. 7.3.13), and a 10 mL aliquot from each
     of the stock standard solutions of selenium (Sect. 7.3.22) and
     thallium (Sect.  7.3.27), to a mixture of 20 mL (1+1) nitric acid and
     20 mL (1+1) hydrochloric acid and diluting to 500 mL with ASTM type
     I water.  Store in a Teflon bottle.

7.7  TUNING SOLUTION - This solution is used for adjusting the aerosol
     argon gas flow prior to calibration and analysis  (Sect. 9.4).  The
     solution  is prepared by adding a 5 mL aliquot from each of the stock
     standard  solutions of copper (Sect. 7.3.11) and lead (Sect. 7.3.13)
     to a mixture of 20 mL (1+1) nitric acid and 20 mL (1+1) hydrochloric
     acid and  diluting to 500 mL with ASTM type I water.   Store in a
     Teflon bottle.

7.8  LABORATORY PERFORMANCE CHECK (LPC) SOLUTION - This solution is
     prepared  by adding the following listed aliquot volumes of the
     individual  stock standards to the mixture of 20 mL (1+1)  nitric acid
     and 20 mL (1+1)  hydrochloric acid and diluting to 500 mL with ASTM
     type I water.  Immediately transfer the freshly prepared LPC to an
     acid cleaned, not previously used, Teflon bottle.

                           Stock         Aliquot         Analyte
            Analvte       Solution       Vol.  mL       Cone.  uq/mL

              Ag           7.3.24          1.0             0.5
              Al            7.3.1           1.0             2.0
              As           7.3.3           1.0             2.0
              B            7.3.6           1.0             2.0
              Ba           7.3.4           2.0             2.0
              Be           7.3.5           2.0             2.0


                                 49

-------
              Ca
              Cd
              Co
              Cr
              Cu
              Fe
              Hg
              K
              Li
              Mg
              Mn
              Mo
              Na
              Ni
              P
              Pb
              Sb
              Se
              Si02
              Sn
              Sr
              Tl
              V
              Zn
7.3.8
7.3.7
7.3.10
7.3.9
7.3.11
7.3.12
7.3.17
7.3.21
7.3.14
7.3.15
7.3.16
7.3.18
7.3.25
7.3.19
7.3.20
7.3.13
7.3.2
7.3.22
7.3.23
7.3.28
7.3.26
7.3.27
7.3.29
7.3.31
2.0
5.0
1.0
5.0
1.
2,
  0
  0
2.0
5.0
1.0
2.0
2.0
1.0
2.0
 2.0
 2.0
 2.0
 2.0
 2.0
 2.0
 2.0
10.0
  .0
  .0
  .0
  .0
  .0
 2.0
10.0
 2.0
 2.0
 2.0
10.0
  .0
  .0
  .0
 2.0
 2.0
                2.
                2.
                2.
                2.
                2,
                2.
                2.
                2.
7.9  SPECTRAL INTERFERENCE CHECK (SIC) SOLUTIONS - Once the interelement
     spectral interference correction factors have been determined (Sect.
     4.1.1) and the procedural routine for their use has been
     established, the operative process should be periodically tested and
     updated as needed.  It is usually not practical to test and update
     the entire corrective process on a daily or weekly basis.  The
     frequency of confirming and/or updating the entire corrective
     process is the responsibility of the analyst and should be dictated
     by instrument stability, type of samples analyzed and the expected
     interference encountered.  The following procedure is recommended
     for testing and verifying the interelement spectral correction
     process.  A general description of the procedure is given in
     Sect. 7.9.1.  In Sect. 7.9.2 thru 7.9.4 instructions are given for
     the preparation of SIC solutions that are specific to the
     wavelengths and background correction locations given in Table 1.
     The SIC solutions are designed to monitor and detect a 10% change in
     a partial list of the interference correction factors given in Table
     3.  The factors selected for monitoring were determined by dividing
     each of the listed correction factors by 10 and multiplying the
     quotient by the concentration of the interfering element in the
     respective SIC solution given below.  If the resulting product was a
     number equal to or greater than two times the analyte MDL, the
     correction factor was included for monitoring.

     7.9.1  Prepare an acid matrix solution of the interfering element at
            a high level of concentration (e.g., 50 mg/L).  Complete 10
            analyses of the solution and determine the standard deviation
                                 50

-------
       of the mean concentration.  From the data calculate a
       concentration equal to 4.52 times the standard deviation.
       (This calculated concentration estimates the 95% confidence
       interval of the interferent mean concentration).  Multiply
       the calculated concentration by the correction factor to be
       tested.  Disregarding the numerical sign of the product, add
       a concentration value equivalent to 2.2X the MDL of the
       analyte that is being corrected.  The sum of the two
       concentrations, when bisected by the calibration blank,
       describes an acceptable apparent analyte concentration range.
       If the apparent analyte concentration from the analysis of
       the interferent solution is within the acceptable range, the
       correction process is considered to be in control.  If the
       apparent analyzed concentration is outside the range, as
       either a positive or negative concentration, a change in the
       correction process is indicated and an update of the process
       may be required.

       NOTE:  The interfering solution should be analyzed more than
       once to confirm a change occurred with adequate rinse time
       between solutions and before the subsequent analysis of the
       calibration blank.

7.9.2  SIC solution I (50 mg/L Mo) - Add a 5 ml aliquot of the stock
       standard solution of molybdenum (Sect. 7.3.18)  to a mixture
       of 4 ml (1+1)  nitric acid and 4 ml  (1+1) hydrochloric acid
       and dilute to  100 ml with ASTM type I water.  Store in a
       Teflon bottle.  This solution is used to evaluate the
       molybdenum interelement spectral  correction factors on the
       analytes:  Al,  Sb,  Se,  Sn, and V.  (See Table 3).

7.9.3  SIC solution II (10 mg/L Co; 20 mg/L Cr, Mn and  V;  and 40
       mg/L Cu)  - Add a 1 mL aliquot from the stock standard
       solution  of cobalt (Sect. 7.3.10),  a 2 mL aliquot from each
       of the stock standard solutions of manganese (Sect.  7.3.16)
       and vanadium (Sect.  7.3.29) and a 4 mL aliquot  from the stock
       standard  solutions of chromium (Sect.  7.3.9) and copper
       (7.3.11)  to a  mixture of 4 mL (1+1)  nitric acid  and 4 mL
       (1+1)  hydrochloric acid and dilute  to 100 mL with ASTM Type I
       water.   Store  in a Teflon bottle.   This  solution is used to
       evaluate  the following list of interelement spectral
       correction factors (See Table 3).

                      Analvte              Interferent

                         Pb                     Co
                         Sb                     Cr
                         Mo                     Mn
                         As                     V
                         Be                     V
                         Zn                     Cu
                            51

-------
    7.9.4
SIC Solution III (20 mg/L Ni,  30 mg/L Al and 150 mg/L Fe) -
Add a 2 ml aliquot from the stock standard solution of nickel
(Sect. 7.3.19), a 3 ml aliquot from the stock standard
solution of aluminum (Sect. 7.3.1) and a 15 ml aliquot from
the stock standard solution of iron (Sect. 7.3.12) to a
mixture of 4 mL (1+1) nitric acid and 4 ml (1+1) hydrochloric
acid and dilute to 100 ml with ASTM Type 1 water.  Store in a
Teflon bottle.  This solution is used to evaluate the
following list of interelement spectral correction factors
(See Table 3).
                          Analvte

                             Sb
                             In
                             As
                             Ag
                             Cr
                             Mn
                             V
                                    Interferent

                                         Ni
                                         Ni
                                         Al
                                         Fe
                                         Fe
                                         Fe
                                         Fe
.10  LABORATORY  FORTIFYING STOCK SOLUTION  -  This  solution  is  used  in
    preparing the  laboratory fortified blank and the  laboratory
    fortified sample matrix.  Prepare the solution  in a 200-mL
    volumetric  flask by adding the  following listed aliquot  volumes  of
    the  individual  stock solutions  to a mixture  of  4  mL (1+1)  nitric
    acid and 20 mL (1+1) hydrochloric acid.   Dilute to the mark with
    ASTM type I water.   Transfer the freshly prepared solution to a
    Teflon  bottle  for storage.
           Stock
           Analvte

             Ag
             Al
             As
             B
             Ba
             Be
             Cd
             Co
             Cr
             Cu
             Fe
             Hg
             Li
             Mn
             Mo
             Ni
             P
             Pb
              Aliquot
              Solution
               7.3,
               7.3,
   ,24
   .1
7.3.3
7.3.6
7.3.4
7.3.5
7.3.7
   ,10
 .3.9
   ,11
   ,12
               7.3.
               7.
               7.3.
               7.3.
               7.3.
               7.3.
               7.3.
               7.3,
               7.3,
               7.3.
    17
    14
    16
    18
    19
    20
               7.3.13
Analyte
Vol. mL

  2.0
  5.0
  5.0
  5.0
 10.0
  2.0
  2.0
  2.0
 10.0
  5.0
  5.0
  2.0
 10.0
  5.0
  2.0
  5.0
 10.0
  5.0
Cone. ug/mL

    2.5
   25
   25
   25
   25
    5
   10
   10
   25
   25
   25
    5
   25
   25
   10
   25
   50
   25
                                52

-------
              Sb
              Se
              Si02
              Sn
              Sr
              Tl
              V
              Zn
7.3.2
7.3.22
7.3.23
    28
7.3
7.3
7.3
   ,26
    27
7.3.29
7.3.31
10.0
10.0
 5.0
 2.0
10.0
10.0
 2.0
10.0
25
25
25
10
2S
25
10
25
            NOTE:  The analytes Ca, K, Mg, and Na are not included in the
            fortifying stock solution because their concentrations vary
            widely in environmental samples.  The analytes B and Si02
            should be disregarded if samples are processed and diluted in
            borosilicate labware because of the known contamination that
            occurs from borosilicate glass.

7.11 LABORATORY FORTIFIED BLANK (LFB) - To a 100 mL aliquot of ASTM type
     water add 2 mL of (1+1) nitric acid, 1.0 mL (1+1) hydrochloric acid
     and 2 mL of the laboratory fortifying stock solution (Sect. 7.10).
     The LFB must be carried through the entire sample preparation
     procedure and analysis scheme.  The final  solution should be diluted
     to 50 mL as are the samples.   Listed below is the expected
     concentration of each analyte based on the original  100 mL of water.
               Analvte

                 Ag
                 Al
                 As
                 B
                 Ba
                 Be
                 Cd
                 Co
                 Cr
                 Cu
                 Fe
                 Hg
                 Li
                 Mn
                 Mo
                 Ni
                 P
                 Pb
                 Sb
                 Se
                 Si02
                 Sn
                 Sr
                 Tl
                 V
                 Zn
                     Cone.  uq/mL

                         0.05
                         0.5
                         0.5
                         0.5
                         0.5
                         0.1
                         0.2
                         0.2
                         0.5
                         0.5
                         0.5
                         0.1
                         0.5
                         0.5
                         0.2
                         0.5
                         1.0
                         0.5
                         0.5
                         0.5
                         0.5
                         0.2
                         0.5
                         0.5
                         0.2
                         0.5
                                53

-------
     7.12 QUALITY CONTROL SAMPLE - The quality control  sample (Sect.  3.18)
          should be prepared in the same acid matrix as the calibration
          standards at a concentration near 1 mg/L, except silver,  which must
          be limited to a concentration of 0.5 mg/L.  Follow the instructions
          provided by the supplier and store the sample in a Teflon bottle.
          The Quality Assurance Research Division of EMSL-Cincinnati  will
          either supply a quality control sample or provide information where
          one of equal quality can be procured.

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  Prior to collection of an aqueous sample, consideration should be
          given to the type of data required, (i.e., dissolved or total
          recoverable), so that appropriate preservation and pretreatment
          steps can be taken.  Filtration, acid preservation, etc., should be
          performed at the time of sample collection or as soon thereafter as
          practically possible.

     8.2  For determination of dissolved elements, the sample must be filtered
          through a 0.45-/im membrane  filter.   (Glass or plastic filtering
          apparatus is recommended to avoid possible contamination.  Only
          plastic apparatus should be used when determination of boron or
          silica is critical (Sect.1.6).  Use a portion of the filtered sample
          to rinse the filter flask, discard this  portion and collect the
          required volume of filtrate.  Acidify the filtrate with  (1+1) nitric
          acid immediately following filtration to a pH < 2.

     8.3  For the determination of total recoverable elements in aqueous
          samples, acidify with (1+1) nitric acid  at the time of collection to
          a pH < 2 (normally, 3 mL of (1+1) acid per liter of sample is
          sufficient  for most ambient and drinking water samples).  The sample
          should not  be filtered prior to analysis  (Sect. 1.6).

          NOTE: Samples that cannot be acid preserved  at the time  of
          collection  because of sampling limitations or transport  restrictions
          should be acidified with nitric acid to  a pH < 2  upon receipt in
          the laboratory.  Following  acidification, the sample  should  be held
          for 16 hours before withdrawing an aliquot for sample processing.

     8.4  Solid samples usually require  no preservation prior to analysis
          other than  storage at 4°C.

 9.   CALIBRATION AND  STANDARDIZATION

     9.1  Recommended wavelengths  and background  correction locations  are
          listed  in Table  1.   Other  wavelengths  and background correction
          locations may be substituted  if they can provide  the  needed
          sensitivity and  are  corrected  for  spectral interference.   In Table 4
          specific  instrument  operating  conditions are recommended.  However,
          because  of  the difference  among various  makes and models of  spectro-
          meters,  the analyst  should  follow  the  instrument  manufacturer's
                                       54

-------
     instructions, and if possible, approximate the recommended operating
     conditions.

9.2  Allow the instrument to become thermally stable before beginning.
     This usually requires at least 30 min of operation prior to plasma
     optimization, plasma tuning and/or calibration.

9.3  PLASMA OPTIMIZATION - Prior to the use of this method optimize the
     plasma operating conditions using the following procedure. The
     purpose of plasma optimization is to provide a maximum signal  to
     background ratio for the least sensitive element in the analytical
     array. The use of a mass flow controller to regulate the nebulizer
     gas flow rate greatly facilitates the procedure.

     9.3.1  Select an appropriate incident rf power with minimum
            reflected power (see Table 4 for recommendations) and
            aspirate the 1000 fig/ml solution of yttrium (Sect. 7.3.30).
            Following the instrument manufacturer's instructions adjust
            the aerosol  carrier gas flow rate through the nebulizer so a
            definitive blue emission region of the plasma extends
            approximately from 5 to 20 mm above the top of the work
            coil.     Record the nebulizer gas flow rate or pressure
            setting for future reference.

     9.3.2  After establishing the nebulizer gas flow rate, determine the
            solution uptake rate of the nebulizer in mL/min by aspirating
            a known volume acid blank for a period of at least 3 min.
            Divide the spent volume by three and record the uptake  rate.
            Set the peristaltic pump to deliver the uptake rate in  a
            steady even flow.

     9.3.3  After horizontally aligning the plasma and/or optically
            profiling the spectrometer, use the selected instrument
            conditions from Sects. 9.3.1 and 9.3.2,  and aspirate the
            plasma solution (Sect. 7.7), containing 10 jug/mL each of As,
            Pb, Se and Tl.  Collect intensity data at the wavelength peak
            for each analyte at 1 mm intervals from 14 to 18 mm above the
            top of the work coil. (This region of the plasma is commonly
            referred to as the analytical zone.)12  Repeat the process
            using the calibration blank.  Determine the net signal  to
            blank intensity ratio for each analyte for each viewing
            height setting. Choose the height for viewing the plasma that
            provides the largest intensity ratio for the least sensitive
            element of the four analytes.  If more than one position
            provides the same  ratio,  select the position that provides
            the best compromise of intensity ratios of all  four analytes.

     9.3.4  The instrument operating condition finally selected as  being
            optimum should provide the lowest reliable IDLs and MDLs
            similar to those listed in Table 2.
                                 55

-------
     9.3.5  If either the instrument operating conditions, (such as
            incident power and/or nebulizer gas flow rate) are changed,
            or a new torch injector tube having a different orifice i.d.
            is installed, the plasma and plasma viewing height should be
            reoptimized.

     9.3.6  Before daily calibration and after the instrument warm-up
            period (Sect. 9.2), the nebulizer gas flow must be reset to
            the determined optimized flow.  If a mass flow controller is
            being used, it should be either reset to the recorded
            optimized flow-rate or the optional plasma tuning procedure
            given in Sect. 9.4 should be followed to reconfigure the
            plasma.  In order to provide and maintain valid interelement
            spectral correction factors the nebulizer gas flow rate must
            be well controlled.  The change in signal intensity with a
            change in nebulizer gas flow rate for both "hard" (Pb 220.353
            nm) and "soft" (Cu 324.754 nn) lines is illustrated in
            Figure 1.

9.4  PLASMA TUNING (Optional) - This procedure can be used on a daily
     basis to collect the data necessary for fine tuning the plasma to a
     set Cu/Pb concentration ratio that reflects the optimized conditions
     determined in Sect. 9.3.  The analytical zone of the plasma can be
     altered by varying the aerosol carrier gas flow entering the plasma.
     This procedure requires the use of a mass flow controller for
     adjusting the nebulizer gas flow rate to reset the Cu/Pb
     concentration ratio.  (This procedure can be used even when the
     front surface entrance optics degrade in a non-uniform manner over
     the visible and ultraviolet wavelength regions.)

     9.4.1  Set the instrument to the optimized operating conditions
            (Sect. 9.3).  After instrument warm-up, horizontal alignment
            of the plasma and/or optical profiling of the spectrometer,
            aspirate the tuning solution (Sect. 7.7) and collect 10
            replicate measurements of the Cu (324.75 nm) and Pb (220.35
            nm) intensity signals at every 25 mL/min interval over the
            flow rate range of 500 to 800 mL/min.  Repeat the operation
            using the calibration blank solution.  Subtract the
            respective mean blank value and calculate the net mean
            intensity value for both metals at each flow rate.  Plot the
            net mean intensity values versus flow rate as illustrated in
            Figure 1.  From the plot determine the maximum signal
            intensity flow rate for each metal.

     9.4.2  To determine the Cu/Pb concentration ratio,  set the
            instrument to the optimized operating conditions.  After
            warm-up and optical profiling, calibrate the instrument for
            both Cu (324.75 nm) and Pb (220.35 nm) at their respective
            maximum intensity flow rates (See Figure 1,  Cu 750 mL/min, Pb
            535 mL/min) with the calibration blank set at the optimum
            flow (e.g., 620 mL/min).


                                 56

-------
     9.4.3  Reset the nebulizer gas flow to the rate established in Sect.
            9.3.1 (e.g., 620 mL/min) and collect data from 10 replicate
            analyses of the tuning solution (Sect. 7.6).  Ratio the
            determined copper concentration to the  determined lead
            concentration on each analysis and compute the standard
            deviation and mean value of the 10 ratios.  (Note: Disregard
            the fact that the determined concentrations do not equal the
            prepared concentrations of the tuning solution.)  The mean
            value is used for resetting the ratio on a daily basis.

     9.4.4  For tuning the plasma on a daily basis calibrate the
            instrument as described in Sect. 9.4.2.  Reset the nebulizer
            gas flow rate to the optimum flow (e.g. 620 mL/min) and
            analyze the tuning solution.  Calculate the Cu/Pb
            concentration ratio from the analysis.  If the calculated
            ratio is not within two standard deviations of the mean value
            established in Sect. 9.4.3, adjust the nebulizer gas flow and
            reanalyze the tuning solution until  the ratio is within
            range.  Lowering the gas flow rate will increase the lead
            concentration, decrease the copper concentration, and,
            therefore, lower the ratio.  The opposite is true when the
            gas flow is increased.  Day-to-day variations in the
            nebulizer gas flow should be < ± 10 mL/min.  Larger changes
            should alert the analyst to possible instrumental problems.

     9.4.5  Once an acceptable ratio is achieved, the instrument is ready
            for analytical calibration.

     9.4.6  If either the selected instrument operating conditions are
            changed or instrument components replaced that require the
            plasma to be reoptimized (Sect. 9.3.5), the Cu/Pb
            concentration ratio must be reestablished.

9.5  CALIBRATION - Calibrate the instrument according to the instrument
     manufacturer's instructions using the prepared calibration blank
     (Sect. 7.5.1) and CAL solutions (Sect. 7.4).  The following
     operational steps should be used for both CAL solutions and samples.

     9.5.1  Using a peristaltic pump introduce the standard or sample to
            nebulizer at a uniform rate (e.g., 1.2 mL/min).

     9.5.2  To allow equilibrium to be reached in the plasma, aspirate
            the standard or sample solution for  30 sec after reaching the
            plasma before beginning integration  of the background
            corrected signal.

     9.5.3  When possible use the average value  of four 5 sec background
            corrected integration periods as the atomic emission signal
            to be correlated to analyte concentration.

     9.5.4  Between each standard^or sample,  flush the nebulizer and
            solution uptake system with the rinse blank acid solution

                                 57

-------
            (Sect. 7.5.3) for 60 sec or for the required period of time
            to ensure that analyte memory effects are not occurring.

9.6  Analyze the LPC solution (Sect. 7.8) and calibration blank (Sect.
     7.5.1) immediately following calibration, after every tenth sample
     and at the end of the sample run.  The analyzed value of each
     analyte in the LPC solution should be within 95% to 105% of its
     expected value.  If an analyte value is outside the interval,
     reanalyze the LPC.  If the analyte is again outside the ± 5% limit,
     the instrument should be recalibrated and all samples following the
     last acceptable LPC solution should be reanalyzed.

9.7  Periodically verify the validity of the interelement spectral
     interference correction process.  The frequency of this testing is
     the responsibility of the analyst, however, confirmation prior to
     analysis of solid sample extracts is particularly useful.  See Sect.
     7.9 for guidance and criteria.

9.8  If methods of standard addition are required, the following
     procedure is recommended.

     9.8.1  The standard addition technique13  involves  preparing new
            standards in the sample matrix by adding known amounts of
            standard to one or more aliquots of the processed sample
            solution.  This technique compensates for a sample constitu-
            ent that enhances or depresses the analyte signal thus
            producing a different slope from that of the calibration
            standards.  It will not correct for additive interference
            that causes a baseline shift.  The simplest version of this
            technique is the single-addition method.  The procedure is
            as follows.  Two identical aliquots (Volume Vx)  of the sample
            solution, are taken.  To the first (labeled A) is added a
            small volume Vs of a standard analyte solution of
            concentration cs.   To the second (labeled B)  is  added  the
            same volume Vs of the solvent.   The analytical  signals of
            A and B are measured and corrected for non-analyte signals.
            The unknown sample concentration cx is calculated:
                    Cx  =
                                    cs
                           
-------
                 1.  The analytical  curve must be linear.

                 2.  The chemical  form of the analyte added must respond the
                    same as the analyte in the sample.

                 3.  The interference effect must be constant over the working
                    range of concern.

                 4.  The signal  must be corrected for any additive interfer-
                    ence.

10.   QUALITY CONTROL

     10.1 Each laboratory using this method is required to operate a formal
          quality control (QC)  program.  The minimum requirements of this
          program consist of an initial demonstration of laboratory capability
          and analysis of laboratory reagent blanks and fortified blanks and
          samples as a continuing check on performance.  The laboratory is
          required to maintain  performance records that define the quality of
          data generated.

     10.2 INITIAL DEMONSTRATION OF PERFORMANCE.

          10.2.1 The initial demonstration of performance is used to
                 characterize instrument performance (MDLs and linear calibra-
                 tion ranges) and laboratory performance (analysis of quality
                 control sample)  for analyses conducted by this method.

          10.2.2 MDLs should be established for all analytes, using reagent
                 water (blank)  fortified at a concentration of two to three
                 times the estimated detection limit .   To determine MDL
                 values, take seven replicate aliquots of the fortified
                 reagent water and process through the entire analytical
                 method.  Perform all calculations defined in the method and
                 report the concentration values in the appropriate units.
                 Calculate the MDL as follows:

                  MDL = (t) x (S)

                  where, t = Student's t value for a 99% confidence level and
                             a standard deviation estimate with n-1 degrees of
                             freedom [t = 3.14 for seven replicates].

                         S = standard deviation of the replicate analyses.

                 MDLs should be determined every six months or whenever there
                 is a significant change in the background or instrument
                 response.

          10.2.3 Linear calibration ranges -  The upper limit of the linear
                 calibration range should be established for each analyte by
                 determining the signal responses from a minimum of three

                                      59

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            different concentration standards, one of which is close to
            the upper limit of the linear range.  The linear calibration
            range which may be used for the analysis of samples should be
            judged by the analyst from the resulting data.  Linear
            calibration ranges should be determined whenever there is a
            significant change in instrument response and every six
            months for those analytes that periodically approach their
            linear limit.

     10.2.4 Quality Control Sample (QCS) - When beginning the use of this
            method and on a quarterly basis, verify acceptable laboratory
            performance with the preparation and analyses of a quality
            control sample (Sect. 7.12).  The QCS is carried through the
            entire analytical  operation of the method.   If the determined
            concentrations are not within ± 5% of the stated values of 1
            mg/L,  laboratory performance is unacceptable.  The source of
            the problem should be identified and corrected before
            continuing analyses.

10.3 ASSESSING LABORATORY PERFORMANCE - REAGENT AND FORTIFIED BLANKS

     10.3.1 Laboratory reagent blank (LRB) - The laboratory must analyze
            at least one LRB (Sect.  7.5.2) with each set of samples.   LRB
            data are used to assess  contamination from  the laboratory
            environment.  If an analyte value in the reagent blank
            exceeds its determined MDL, then laboratory or reagent
            contamination should be  suspected.  Any determined source of
            contamination should be  corrected and the samples reanalyzed.

     10.3.2 Laboratory fortified blank (LFB) - The laboratory must
            analyze at least one LFB (Sect.  7.11) with  each batch of
            samples.   Calculate accuracy as  percent recovery (Sect.
            10.4.2).   If the recovery of any analyte falls outside the
            control limits (Sect. 10.3.3), that analyte is judged out of
            control,  and the source  of the problem should be identified
            and resolved before continuing analyses.

     10.3.3 Until  sufficient LFB data become available  (usually a minimum
            of 20  to  30 analyses), the laboratory should assess
            laboratory performance against recovery limits of 85-115%.
            When sufficient internal  performance data becomes available,
            develop control  limits from the  percent mean recovery (x)  and
            the standard deviation (S)  of the  mean recovery.   These data
            are used  to establish upper and  lower control  limits as
            fol1ows:

                  UPPER CONTROL LIMIT = x +  3S
                  LOWER CONTROL LIMIT = x -  3S
                                 60

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                 After each five to ten  new recovery measurements,  new control
                 limits should be calculated using  only the  most  recent 20 to
                 30 data points.

     10.4 ASSESSING ANALYTE RECOVERY -  LABORATORY FORTIFIED  SAMPLE  MATRIX

          10.4.1  The laboratory must add a known  amount of each analyte to a
                 minimum of 10% of the  routine  samples  or one sample per
                 sample set,  whichever  is greater.   Ideally  for water samples,
                 the analyte concentration should be the same as  that used in
                 the LFB (Sect. 10.3.2).  This  is also  recommended  for solid
                 samples,  however,  the  concentration added should be expressed
                 as mg/kg and calculated by multiplying the  values  given in
                 Sect. 7.11 by the factor 100.  Over time, samples  from all
                 routine sample sources  should  be fortified.

          10.4.2  Calculate the percent  recovery for each analyte, corrected
                 for background concentrations  measured in the unfortified
                 sample, and compare these values to the control  limits
                 established in Sect.  10,3.3 for  the analyses of  LFBs.
                 Recovery calculations  are not  required if the concentration
                 added is less than 10%  of the  sample background  concen-
                 tration.   Percent recovery may be  calculated in  units
                 appropriate to the matrix, using the following equation:


                     R =  Cs  " C    x 100
                            s

                    where, R  = percent  recovery.
                           Cs = fortified sample  concentration.
                           C  = sample  background concentration.
                           s  = concentration equivalent of  analyte added to
                               sample.

          10.4.3  If recovery of any analyte falls outside the designated range
                 and laboratory performance for that analyte is shown to be in
                 control (Sect. 10.3),  the recovery problem  encountered with
                 the fortified sample is judged to  be matrix related, not
                 system related.  The data user should  be informed  that the
                 result for that analyte in the unfortified  sample  is suspect
                 due to matrix effects  and analysis by  method of  standard
                 addition (Sect. 9.8)  should be considered.

11.   PROCEDURE

     11.1 AQUEOUS SAMPLE PREPARATION -  DISSOLVED  ELEMENTS

          11.1.1  For the determination  of dissolved elements in ground and
                 surface waters, take a  100 mL  (± 1 mL) aliquot of the
                 filtered acid preserved sample,  add 2  mL of (1+1)  nitric acid


                                      61

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            and 1 ml (1+1) hydrochloric acid.  The sample is now ready
            for analysis.  Allowance for sample dilution should be made
            in the calculations.

            NOTE: If a precipitate is formed during acidification,
            transport or storage, the sample aliquot must be treated
            using the procedure in Sect. 11.2.1 prior to analysis.

11.2 AQUEOUS SAMPLE PREPARATION - TOTAL RECOVERABLE ELEMENTS

     11.2.1 For determination of total  recoverable elements in water or
            waste water, other than marine and estuarine water, take a
            100 mL (± 1 mL) aliquot from a well mixed, acid preserved
            sample and transfer it to a 250-mL Griffin beaker. [For
            drinking water compliance monitoring certain analytes require
            4X preconcentration prior to analysis (Sect. 1.7)].  Add 2 mL
            of (1+1) nitric acid and 1.0 mL of (1+1) hydrochloric acid.
            Heat the sample.on a hot plate at 85°C until the volume has
            been reduced to approximately 20 mL, ensuring that the sample
            does not boil.  (A spare beaker containing 20 mL of water can
            be used as a gauge.)

               NOTE: For proper heating adjust the temperature control  of
               the hot plate such that  an uncovered beaker containing
               50 mL of water located in the center of the hot plate can
               be maintained at a temperature no higher than 85°C.
               Evaporation time for 100 mL of sample at 85°C is
               approximately 2 h with the rate of evaporation rapidly
               increasing as the sample volume approaches 20 mL.

            Cover the beaker with a watch glass and reflux for 30 min.
            Slight boiling may occur but vigorous boiling should be
            avoided.   Allow to cool  and quantitatively transfer to
            either a 50-mL volumetric or a 50-mL class A stoppered
            graduated cylinder.  Dilute to volume with ASTM type I water
            and mix.  Centrifuge the sample or allow to stand overnight
            to separate insoluble material.  The sample is now ready for
            analysis.   Because the effects of various matrices on the
            stability of diluted samples cannot be characterized,  samples
            should be analyzed as soon  as possible after preparation.

     11.2.2 For determination of total  recoverable elements in marine and
            estuarine water,  take a 100 mL aliquot from a well  mixed,
            acid preserved sample and transfer to a 250-mL Griffin
            beaker.  Add 2 mL of (1+1) nitric acid and heat on a hot plate
            at 85°C until  the volume has been reduced to approximately
            25 mL,  ensuring that the sample does not boil.  (See NOTE in
            Sect.  11.2.1).   Cover the beaker with a watch glass and
            reflux for 30 min.   Slight  boiling may occur but vigorous
            boiling should be avoided.   Allow to cool  and dilute  to 100
            mL with ASTM type I water.   Centrifuge the sample or  allow  to
                                 62

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            stand overnight to separate insoluble material.   The sample
            is now ready for analysis by the method of standard addition
            (Sect. 9.8).  Because the effects of various matrices on the
            stability of diluted samples cannot be characterized, samples
            should be analyzed as soon as possible after preparation.

11.3 SOLID SAMPLE PREPARATION - TOTAL RECOVERABLE ELEMENTS

     11.3.1 For determination of total recoverable elements  in solid
            samples (sludge, soils,  and sediments), mix the  sample
            thoroughly to achieve homogeneity and weigh accurately a 1.0
            ± 0.01 g portion of the sample.  Transfer to a 250-mL
            Phillips beaker. Add 4 mL (1+1) nitric acid and  10 mL (1+4)
            hydrochloric acid.  Cover with a watch glass.  Heat the
            sample on a hot plate and gently reflux for 30 min.  Very
            slight boiling may occur, however, vigorous boiling must be
            avoided to prevent the loss of the HC1-H20 azeotrope.

               NOTE:  For proper heating adjust the temperature control
               of the hot plate such that an uncovered Griffen beaker
               containing 50 mL of water located in the center of the hot
               plate can be maintained at a temperature of approximately
               but no higher than 85°C.

            Allow the sample to cool and quantitatively transfer to 100-
            mL volumetric flask.  Dilute to volume with ASTM type I water
            and mix.  Centrifuge the sample or allow to stand overnight
            to separate insoluble material.  The sample is now ready for
            analysis.  Because the effects of various matrices on the
            stability of diluted samples cannot be characterized, samples
            should be analyzed as soon as possible after preparation.

               NOTE: Determine the percent solids in the sample  for
               calculating and reporting data on a dry weight basis.  To
               determine the dry weight, transfer a separate, uniform 1 g
               aliquot to an evaporating dish and dry to a constant
               weight at 103-1056C.

11.4 SAMPLE ANALYSIS

     11.4.1 Analyze the samples by the procedural routine described  in
            Sects. 9.5, 9.6 and 9.7.  If method of standard additions are
            required follow the instructions given in Sect.  9.8.  Samples
            having concentrations higher than the established linear
            dynamic range  (LDR) should be diluted into range and
            reanalyzed.  The sample may first be analyzed for trace
            analytes providing the elements  in high concentration do not
            cause a severe matrix effect and any interelement spectral
            interference or shift in  background intensity can be properly
            corrected.
                                 63

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           11.4.2  For  drinking  water  compliance monitoring,  if  the
                  concentration of  a  primary contaminant  is  determined to be
                  90%  of its  MCL or above  and the combined Mg and Ca
                  concentration equals  500 mg/L, the sample  should be analyzed
                  by the standard addition technique (Sect.  9.8).

 12.  CALCULATIONS

     12.1  Sample  data should be reported  in units of mg/L for  aqueous samples
           and mg/kg dry weight for solid  samples.  Do not report element
           concentrations below the determined MDL.

     12.2  For aqueous samples  prepared by total recoverable procedure (Sect.
           11.2.1), multiply  solution concentrations by the dilution factor
           0.5.  Round the data to  the thousandth place and report the data in
           mg/L up to  three significant figures.

     12.3  For estuarine  and  marine water  samples prepared by total recoverable
           procedure (Sect. 11.2.2), read  the concentration directly from the
           instrument  and calculate the sample concentration by the procedure
           described in  Sect. 9.8.  Round  the data to the thousandth place and
           report  the  data in mg/L  up to three significant figures.

     12.4  For solid samples  prepared by total  recoverable procedure (Sect.
           11.3) round the solution concentrations (fig/mi, in the analysis
           solution) to the thousandth place and multiply by the dilution
           factor  100.  Report  the data to a 0.1 mg/kg up to three significant
           figures taking into  account the percent solids as noted in Sect.
           11.3 when the  data are reported on a dry weight basis.

     12.5  If additional   dilutions were performed or if a drinking water sample
          was preconcentrated  4x for analysis,  the appropriate factor must  be
          applied to  sample values.

     12.6 The QC data obtained during sample analyses  provide an indication of
          the quality of the sample data and should be provided with the
          sample results.

13.  PRECISION AND ACCURACY

     13.1 Listed in Table 2 are MDLs  determined using  the procedure described
          in Sect. 10.2.2.   The MDLs  were determined in  the reagent blank
          matrix  (best case situation)  following sample  preparation given in
          Sect.  11.2.1.   Teflon beakers were used to avoid  boron and silica
          contamination  from glassware  with  the final  dilution  to 50 mL
          completed in polypropylene  centrifuged tubes.

     13.2 Data obtained  from single laboratory  method  testing are summarized
          in Table 5 for five types of  water samples consisting of  drinking
          water,  surface water, ground  water, and two  wastewater effluents.
          Samples  were prepared using the procedure  described in Sect.  11.2.1.
                                      64

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     For each  matrix,  five  replicate  aliquots were  prepared,  analyzed  and
     the average of the  five  determinations  used  to define  the  sample
     background concentration of each analyte.   In  addition,  two  pairs of
     duplicates were fortified at different  concentration levels.   For
     each method analyte, the sample  background concentration,  mean
     percent recovery,  standard deviation  of the  percent recovery,  and
     relative  percent difference between the duplicate fortified  samples
     are listed in Table 5.  The variance  of the  five replicate sample
     background determinations is included in the calculated  standard
     deviation of the percent recovery when  the analyte concentration  in
     the sample was greater than the  MDL.  The  tap  and well waters  were
     processed in Teflon and  quartz beakers  and diluted in  polypropylene
     centrifuged tubes.   The  nonuse of borosilicate glassware is
     reflected in the precision and recovery data for boron and silica in
     those two sample types.

13.3 Data obtained from single laboratory  method testing  are  summarized
     in Table 6 for three solid samples consisting  of EPA 884 Hazardous
     Soil, SRM 1645 River Sediment, and EPA 286 Electroplating Sludge.
     Samples were prepared  using the procedure  described  in Sect. 11.3.
     For each method analyte, the sample background concentration,  mean
     percent recovery of the fortified additions, the standard deviation
     of the percent recovery, and relative percent  difference between
     duplicate additions were determined as described in  Sect.  13.2.

13.4 Data obtained from single laboratory method testing  when using the
     procedure given in Sect. 11.2.1 but utilizing  the 4X preconcen-
     tration step prior to analysis as required for the determination  of
     certain drinking water contaminants are summarized in  Table  7.
     Seven replicate aliquots of Cincinnati, Ohio,  tapwater were  prepared
     and analyzed to determine background concentrations.   In addition,
     two more  sets of seven replicates each were fortified  at different
     levels of concentration with an attempt to bracket or match  either
     current or proposed Maximum Contaminant Level  concentrations.   For
     each method analyte,  the sample background concentration,
     concentration added,  mean percent recovery of the fortified
     addition, and relative standard deviation of the mean recovery are
     listed in Table 7.  All aliquots were processed  in Teflon beakers
     and diluted to volume in polypropylene centrifuged tubes.  The
     sample analyte less than values indicate 4X MDLs.  The 4X MDL values
     for the analytes: Al, B, Ba, Mn, Sr and Zn are 0.01,   0.002,  0.0003,
     0.0002, 0.0002 and 0.001 mg/L,  respectively.
                                  65

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14.  REFERENCES

     1.
     4.

     5.
    8.
    10,

    11.



    12.



    13.


    14.
 Larson, G.F., V.A. Fassel, R.K. Winge and R.N. Kniseley, "Ultratrace
 Analysis by Optical Emission Spectroscopy: The Stray Light Problem "
 Applied Spectroscopy 30:384 (1976).

 Botto, R. I., "Quality Assurance in Operating a Multielement ICP
 Emission Spectrometer," Spectrochem. Act. 398:95 (1984).

 Botto, R.I., "Long-term Stability of Spectral Interference
 Calibrations for Inductively Coupled Plasma Atomic Emission
 Spectrometry," Analytical Chemistry, 54:1654 (1982).,

 Code of Federal  Regulations 40, Ch. 1,  Pt. 136 Appendix B.

 Handbook for Analytical Quality Control  in Water and Wastewater
 Laboratories, EPA-600/4-79-019.

 "Carcinogens - Working With Carcinogens," Department of Health,
 Education,  and Welfare, Public Health Service,  Center for Disease
 Control,  National  Institute for Occupational  Safety and Health,
 Publication  No.  77-206, Aug.  1977.

 "OSHA Safety and Health Standards,  General Industry," (29 CFR
 1910),  Occupational  Safety and Health Administration, OSHA  2206,
 (Revised, January 1976).

 "Safety in Academic  Chemistry  Laboratories,  American Chemical
 Society Publication,  Committee on Chemical Safety,  3rd  Edition,
 J. •/ / •? •

 "Proposed OSHA Safety and Health Standards,  Laboratories,"
 Occupational  Safety  and Health Administration,  Federal  Register
 July  24,  1986.

 Annual  Book  of ASTM  Standards,  Volume 11.01.

 Wallace, G.F., "Some  Factors Affecting the Performance  of an  ICP
 Sample  Introduction  System," Atomic  Spectroscopy, Vol.  4, pp. 188-
 192 (1983).

 Koirtyohann,  S.R., J.S. Jones  and D.A. Yates, "Nomenclature System
 for the Low-Power Argon  Inductively  Coupled Plasma,"  Analytical
 Chemistry, 52:1965 (1980).

 Winefordner, J.D., "Trace Analysis:   Spectroscopic Methods for
 Elements," Chemical Analysis, Vol. 46, pp. 41-42.

ADDITIONAL BIBLIOGRAPHY

 14.1    Winge, R.K., V.A. Fassel, V.J. Peterson and M.A. Floyd,
       "Inductively Coupled Plasma-Atomic  Emission Spectroscopy: An

                            66

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       Atlas of spectral  Information," Physical  Science Data 20,
       Elsevier Science,  1985.

14.2   Winge, R.K., V.A.  Fassel,  R.N. Kniseley,  F. DeKalb and W.J.
       Haas, Jr., "Determination  of Trace Elements in Soft, Hard and
       Saline Waters by Inductively Coupled Plasma, Multi-Element
       Atomic Emission spectroscopic (ICP-AES) Technique,"
       Spectrochemica Acta, 328:327 (1977).

14.3   Garbarino, J.R. and Taylor, H.E., "An Inductively-Coupled
       Plasma Atomic Emission Spectrometric Method for Routine Water
       Quality Testing,"  Applied  Spectroscopy 33, No. 3(1979).

14.4   Method 200.7, Inductively  Coupled Plasma-Atomic Emission
       Spectrometer Method for Trace Element Analysis of Water and
       Wastes. Revision 1.0, July, 1979, U.S. Environmental
       Protection Agency, Office  of Research and Development,
       Environmental Monitoring and Support Laboratory, Cincinnati,
       Ohio  45268.

14.5   Appendix to Method 200.7,  Inductively Coupled Plasma Atomic
       Analysis of Drinking Water, Revision 1.3, March, 1987, U.S.
       Environmental Protection Agency, Office of Research and
       Development, Environmental Monitoring Systems Laboratory,
       Cincinnati, Ohio  45268.
                            67

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 TABLE  1.   RECOMMENDED WAVELENGTHS WITH LOCATIONS FOR BACKGROUND CORRECTION AND
           ESTIMATED INSTRUMENT DETECTION LIMITS (IDL)
 Analyte
Wavelength, nm1
  Location for
Bkgd. Correction
Estimated IDLs
    mg/L<2>
Ag
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Ho
Na
Ni
P
Pb
Sb
Se
Si02
Sn
Sr
Tl
V
Zn
328.068
308.215
193.696
249.678x2
493.409
313.042
315.887
226.502
228.616
205.552x2
324.754
259.940
194.227x2
766.491
670.784
279.079
257.610
203.844
588.995
231.604x2
214.914x2
220.353
206.833
196.090
251.611
189.980x2
421.552
190.864
292.402
213.856x2
+0.070 nm
+0.070 nm
+0.070 nm
+0.035 nm
-0.064 nm
-0.064 nm
+0.070 nm
+0.070 nm
-0.064 nm
-0.032 nm
-0.064 nm
+0.070 nm
-0.032 nm
-0.064 nm
+0.070 nm
-0.064 nm
+0.070 nm
-0.064 nm
+0.070 nm
+0.035 nm
+0.035 nm
-0.064 nm
+0.070 nm
+0.070 nm
-0.064 nm
-0.032 nm
+0.070 nm
-0.064 nm
+0.070 nm
+0.035 nm
0.005
0.05
0.03
0.006
0.001
0.0007
0.02
0.002
0.007
0.007
0.003
0.007
0.02
0.7
0.005
0.03
0.0008
0.02
0.03
0.009
0.09
0.03
0.03
0.08
0.02
0.02
0.0006
0.03
0.009
0.002
(1)   Wavelength x 2 indicates wavelength is read in second order.

(2)   The IDLs were estimated from three times the standard deviation of 10 replicate
     measurements of the calibration blank.*  .The calculated IDL was rounded upward and
     reported to a single digit.
                                          68

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        TABLE  2.   TOTAL RECOVERABLE  METHOD DETECTION  LIMITS  (MDL)
r~
Anal
Ag
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
|Na
FNi
P
Pb
Sb
Se
MDLs
vte Aaueous. ma/L<1)
0.002
0.02
0.008
0.003
0.001
0.0003
0.01
0.001
0.002
0.004
0.003
0.03*
0.007
0.3
0.001
0.02
0.001
0.004
0.03
0.005
0.06
0.01
0.008
0.02

Solids. ma/Kq<2)
0.3
3
2
-
0.2
0.1
2
0.2
0.4
0.8
0.5
6
2
60
2
3
0.2
1
20
1
12
2
2
5
Si02 0.02
Sn
Sr
Tl
V
Zn
(1)
(2)
0.007
0.0003
0.02
0.003
0.002
MDL concentrations are computed for original
preconcentration during preparation. Samples
diluted in 50-mL plastic centrifuge tubes.
Based on aqueous solution determination.
2
0.1
3
1
0.3
matrix with allowance for 2x sample
were processed in Teflon and

Boron not reported because of glassware contamination.
Silica not determined in solid samples. •
Elevated value due to fume hood contamination.
                                    69

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TABLE 4.  INDUCTIVELY COUPLED PLASMA INSTRUMENT OPERATING CONDITIONS
           Incident rf power
           Reflected rf power
           Viewing height above
             work coil
           Injector tube orifice i.d.
           Argon supply
           Argon pressure
           Coolant argon flow rate
           Aerosol carrier argon
             flow rate
           Auxiliary (plasma)
             argon flow rate
           Sample uptake rate
            controlled to
 1100 watts
 < 5 watts

  15 mm
   1 mm
liquid argon
  40 psi
  19 L/min

620 mL/min

300 mL/min

1.2 mL/min
                                     72

-------
 PB-CU ICP-AES EMISSION PROFILE
32

30

28

26

24

22

20

18

16

14h
  Net Emission Intensity Counts /Thousands
12
 475   525  575   625   675   725   775  825
     Nebulizer Argon Flow Rate - mL/min
              Copper
Lead
                 FIGURE 1

                   73

-------
               TABLE 5.   PRECISION AND RECOVERY DATA IN AQUEOUS  MATRICES

                                        TAP WATER
         SAMPLE     LOW
          CONC     SPIKE
ANALYTE   mg/L      mg/L
 AVERAGE
RECOVERY
          S(R)
RPD
 HIGH    AVERAGE
SPIKE   RECOVERY
 mg/L     R(%)    S(R)
RPD
Ag
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Si02
Sn
Sr
Tl
V
Zn
<0.002
0.185
<0.008
0.023
0.042
<0.0003
35.2
<0.001
<0.002
<0.004
<0.003
0.008
<0.007
1.98
0.006
8.08
<0.001
<0.004
10.3
<0.005
0.045
<0.01
<0.008
<0.02
6.5
<0.007
0.181
<0.02
<0.003
0.005
0.05
0.05
0.05
0.1
0.05
0.01
5.0
0.01
0.02
0.01
0.02
0.1
0.05
5.0
0.02
5.0
0.01
0.02
5.0
0.02
0.1
0.05
0.05
0.1
5.0
0.05
0.1
0.1
0.05
0.05
95
98
108
98
102
100
101
105
100
110
103
106
103
109
103
104
100
95
99
108
102
95
99
87
104
103
102
101
101
101
0.7
8.8
1.4
0.2
1.6
0.0
8.8
3.5
0.0
0.0
1.8
1.0
0.7
1.4
6.9
2.2
0.0
3.5
3.0
1.8
13.1
0.7
0.7
1.1
3.3
2.1
3.3
3.9
0.7
3.7
2.1
1.7
3.7
0.0
2.2
0.0
1.7
9.5
0.0
0.0
4.9
1.8
1.9
2.3
3.8
1.5
0.0
10.5
2.0
4.7
9.4
2.1
2.0
3.5
3.4
5.8
2.1
10.9
2.0
9.0
0.2
0.2
0.2
0.4
0.2
0.1
20.0
0.1
0.2
0.1
0.2
0.4
0.2
20.0
0.2
20.0
0.1
0.2
20.0
0.2
0.4
0.2
0.2
0.4
20.0
0.2
0.4
0.4
0.2
0.2
96
105
101
98
98
99
103
98
99
102
101
105
100
107
110
100
99
108
106
104
104
100
102
99
96
101
105
101
99
98
0.0
3.0
0.7
0.2
0.4
0.0
2.0
0.0
0.5
0.0
1.2
0.3
0.4
0.7
1.9
0.7
0.0
0.5
1.0
1.1
3.2
0.2
0.7
0.8
1.1
1.8
0.8
0.1
0.2
0.9
0.0
3.1
2.0
0.5
0.8
0.0
0.9
0.0
1.5
0.0
3.5
0.5
1.0
1.7
4.4
1.1
0.0
1.4
1.6
2.9
1.3
0.5
2.0
2.3
2.3
5.0
1.0
0.3
0.5
2.5
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations,
 <    Sample concentration below established method detection limit.
 *    Spike concentration <10% of sample background concentration.
                                          74

-------
       TABLE  5.   PRECISION AND  RECOVERY DATA  IN AQUEOUS MATRICES  (Cont'd.)

                                    POND WATER
          SAMPLE     LOW
          CONC     SPIKE
ANALYTE   mg/L      mg/L
                     AVERAGE
                    RECOVERY
                              S(R)
RPD
 HIGH  AVERAGE
SPIKE RECOVERY
 mg/L   R(%)   S(R)
RPD
Ag
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Si02
Sn
Sr
Tl
V
Zn
<0.002
0.819
<0.008
0.034
0.029
<0.0003
53.9
<0.001
<0.002
<0.004
0.003
0.875
<0.007
2.48
<0.001
10.8
0.632
<0.004
17.8
<0.005
0.196
<0.01
<0.008
<0.02
7.83
<0.007
0.129
<0.02
0.003
0.006
0.05
0.2
0.05
0.1
0.05
0.01
5
0.01
0.02
0.01
0.02
0.2
0.05
5
0.02
5
0.01
0.02
5
0.02
0.1
0.05
0.05
0.1
5
0.05
0.1
0.1
0.05
0.05
92
88
102
111
96
95
*
107
100
105
98
95
97
106
110
102
*
105
103
96
91
96
102
104
151
98
105
103
94
97
0.0
10.0
0.0
8.9
0.9
0.4
*
0.0
2.7
3.5
2.1
8.9
3.5
0.3
0.0
0.5
*
3.5
1.3
5.6
14.7
2.6
2.8
2.1
1.6
0.0
0.4
1.1
0.4
1.6
0.0
5.0
0.0
6.9
0.0
1.1
0.7
0.0
7.5
9.5
4.4
2.8
10.3
0.1
0.0
0.0
0.2
9.5
0.4
9.1
0.3
7.8
7.8
5.8
1.3
0.0
0.0
2.9
0.0
1.8
0.2
0.8
0.2
0.4
0.2
0.1
20.0
0.1
0.2
0.1
0.2
0.8
0.2
20.0
0.2
20.0
0.1
0.2
20.0
0.2
0.4
0.2
0.2
0.4
20.0
0.2
0.4
0.4
0.2
0.2
94
100
98
103
97
95
100
97
97
103
100
97
98
103
106
96
97
103
94
100
108
100
104
103
117
99
99
97
98
94
0.0
2.9
1.4
2.0
0.3
0.0
2.0
0.0
0.7
1.1
0.5
3.2
0.0
0.2
0.2
0.7
2.3
0.4
0.3
0.7
3.9
0.7
0.4
1.6
0.4
1.1
0.1
1.3
0.1
0.4
0.0
3.7
4.1
0.0
0.5
0.0
1.5
0.0
2.1
2.9
1.5
3.6
0.0
0.4
0.5
1.3
0.3
1.0
0.0
1.5
1.3
2.0
1.0
4.4
0.6
3.0
0.2
3.9
0.0
0.0
S(R)
RPD
 <
 *
Standard deviation of percent recovery.
Relative percent difference between duplicate spike determinations.
Sample concentration below established method detection limit.
Spike concentration <10% of sample background concentration.
                                        75

-------
        TABLE 5.   PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES (Cont'd.)

                                    WELL WATER
          SAMPLE
          CONC
ANALYTE   mg/L
             LOW    AVERAGE
            SPIKE  RECOVERY
             mg/L    R(%)    S(R)
RPD
 HIGH  AVERAGE
SPIKE  RECOVERY
 mg/L    R(%)   S(R)
RPD
Ag
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Ho
Na
Ni
P
Pb
Sb
Se
SiOe
Sn
Sr
Tl
V
Zn
<0.002
0.036
<0.008
0.063
0.102
<0.0003
93.8
0.002
<0.002
<0.004
0.005
0.042
<0.007
6.21
0.001
24.5
2.76
<0.004
35.0
<0.005
0.197
<0.01
<0.008
<0.02
13.1
<0.007
0.274
<0.02
<0.003
0.538
0.05
0.05
0.05
0.1
0.05
0.01
5.0
0.01
0.02
0.01
0.02
0.1
0.05
5.0
0.02
5.0
0.01
0.02
5.0
0.02
0.1
0.05
0.05
0.1
5.0
0.05
0.1
0.1
0.05
0.05
97
107
107
97
102
100
*
90
94
100
100
99
94
96
100
95
*
108
101
112
95
87
98
102
93
98
94
92
98
*
0.7
7.6
0.7
0.6
3.0
0.0
*
0.0
0.4
7.1
1.1
2.3
2.8
3.4
7.6
5.6
*
1.8
11.4
1.8
12.7
4.9
2.8
0.4
4.8
2.8
5.7
0.4
0.0
*
2.1
10.1
1.9
0.7
0.0
0.0
2.1
0.0
1.1
20.0
0.4
1.4
8.5
3.6
9.5
0.3
0.4
4.7
0.8
4.4
1.9
16.1
8.2
1.0
2.8
8.2
2.7
1.1
0.0
0.7
0.2
0.2
0.2
0.4
0.2
0.1
20.0
0.1
0.2
0.1
0.2
0.4
0.2
20.0
0.2
20.0
0.1
0.2
20.0
0.2
0.4
0.2
0.2
0.4
20.0
0.2
0.4
0.4
0.2
0.2
96
101
104
98
99
100
100
96
94
100
96
97
93
101
104
93
*
101
100
96
98
95
99
94
99
94
95
95
99
99
0.2
1.1
0.4
0.8
0.9
0.0
4.1
0.0
0.4
0.4
0.5
1.4
1.2
1.2
1.0
1.6
*
0.2
3.1
0.2
3.4
0.2
1.4
1.1
0.8
0.2
1.7
1.1
0.4
2.5
0.5
0.8
1.0
2.1
1.0
0.0
0.1
0.0
1.1
1.0
1.5
3.3
3.8
2.3
1.9
1.2
0.7
0.5
1.5
0.5
0.9
0.5
4.0
3.4
0.0
0.5
2.2
3.2
1.0
1.1
S(R)
RPD
 <
 *
Standard deviation of percent recovery.
Relative percent difference between duplicate spike determinations.
Sample concentration below established method detection limit.
Spike concentration <10% of sample background concentration.
                                        76

-------
  TABLE 5.  PRECISION AND RECOVERY DATA IN AQUEOUS  MATRICES (Cont'd.)


SAMPLE LOW
CONC SPIKE
ANALYTE mg/L mg/L
S
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
f* * f\
Si02
Sn
Sr
Tl
V
Zn
=;.;.. - ..•
S(R)
RPD
0.009
1.19
<0.008
0.226
0.189
<0.0003
87.9
0.009
0.016
0.128
0.174
1.28
<0.007
10.6
0.011
22.7
0.199
0.125
236
0.087
4.71
0.015
<0.008
<0.02
16.7
0.016
0.515
<0.02
0.003
0.160
0.05
0.05
0.05
0.1
0.05
0.01
5.0
0.01
0.02
0.01
0.02
0.1
0.05
5.0
0.02
5.0
0.01
0.02
5.0
0.02
0.1
0.05
0.05
0.1
5.0
0.05
0.1
0.1
0.05
0.05
Standard deviation
Relative percent di

AVERAGE
RECOVERY
D (®/ \
\ /
92
*
99
217
90
94
*
89
95
*
98
*
102
104
103
100
*
110
*
122
*
91
97
108
124
90
103
105
93
98
of percent
fference b<
S(R)
=•'•' - - "—
1.5
*
2.1
16.3
6.8
0.4
*
2.6
3.1
*
33.1
*
1.4
2.8
8.5
4.4
*
21.2
*
10.7
*
3.5
0.7
3.9
4.0
3.8
6.4
0.4
0.9
3.3
recovery
stween dii
^^-~ — — - —
HIGH
SPIKE
RPD mg/L
3.6 0.2
0.9 0.2
6.1 0.2
9.5 0.4
1.7 1 0.2
1.1
0.6
2.3
0.0
1.5
4.7
2.8
3.9
1.3
3.2
0.0
2.0
6.8
0.0
4.5
2.6
5.0
2.1
10.0
0.9
0.0
0.5
1.0
2.0
1.9
0.1
20.0
0.1
0.2
0.1
0.2
0.4
0.2
20.0
0.2
20.0
0.1
0.2
20.0
0.2
0.4
0.2
0.2
0.4
20.0
0.2
0.4
0.4
0.2
0.2
•
nlirato cn-ilca Ho
===^=
AVERAGE
RECOVERY
:
95
113
93
119
99
100
101
97
93
97
98
111
98
101
105
92
104
102
*
98
*
96
103
101
108
95
96
95
97
101
•h a v»m -i Y\ i -t- •! i
" - - -— —
S(R)
- 	
0.1
12.4
2 1
t» * J.
13.1
1.6
0.4
3.7
0 4
w • ~
0 4
v * ~
2.4
3.0
7.0
0 5
V • V
0.6
0.8
1 i
± • J.
1.9
1.3
*
0.8
*
1.3
1.1
2.6
1.1
1.0
1 6
1 • \J
0 0
V * v
0 2
V • f—
1.0
•Mrt t+
                                                                            RPD
                                                                            0.0
                                                                            2.1
                                                                            6.5
                                                                          20.9
                                                                            0.5

                                                                            1.0
                                                                            0.0
                                                                            1.0
                                                                            0.5
                                                                            2.7

                                                                            1.4
                                                                            0.6
                                                                            1.5
                                                                            0.0
                                                                            0.5

                                                                            0.2
                                                                           0.3
                                                                           0.9
                                                                           0.4
                                                                           1.1

                                                                           1.4
                                                                           2.9
                                                                           2.9
                                                                           7.2
                                                                           0.8

                                                                           0.0
                                                                           0.2
                                                                           0.0
                                                                           0.5
                                                                           1.4
         •          ---_, — __ vvv.,Wx*n N**4|^ii^,
-------
      TABLE 5.  PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES  (Cont'd.)


                              INDUSTRIAL  EFFLUENT
ANALYTE
Ag
• ij3
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
* *3
K
Li
Mg
* *3
Mn
Mo
Na
Ni
p
Pb
Sb
Se
Si02
Sn
Sr
Tl
V
Zn
SAMPLE LOW
CONC SPIKE
mg/L mg/L
<0.003
0.054
<0.02
0.17
0.083
<0.0006
500
0.008
<0.004
0.165
0.095
0.315
<0.01
2.87
0.069
6.84
0.141
1.27
1500
0.014
0.326
0.251
2.81
0.021
6.83
<0.01
6.54
<0.03
<0.005
0.024
0.05
0.05
0.05
0.1
0.05
0.01
5.0
0.01
0.02
0.01
0.02
0.1
0.05
5.0
0.02
5.0
0.01
0.02
5.0
0.02
0.1
0.05
0.05
0.1
5.0
0.05
0.1
0.1
0.05
0.05
AVERAGE
RECOVERY
R(%)
88
88
82
162
86
94
*
85
93
*
93
88
87
101
103
87
*
*
*
98
105
80
*
106
99
87
*
87
90
89
S(R)
0.0
11.7
2.8
17.6
8.2
0.4
*
4.7
1.8
*
23.3
16.4
0.7
3.4
24.7
3.1
*
*
*
4.4
16.0
19.9
*
2.6
6.8
0.7
*
1.8
1.4
6.0
HIGH
SPIKE
RPD mg/L
0.0
12.2
9.8
13.9
1.6
1.1
2.8
6.1
5.4
4.5
0.9
1.0
2.3
2.4
5.6
0.0
1.2
0.0
2.7
3.0
4.7
1.4
0.4
3.2
1.7
2.3
2.0
5.8
4.4
4.4
0.2
0.2
0.2
0.4
0.2
0.1
20.0
0.1
0.2
0.1
0.2
0.4
0.2
20.0
0.2
20.0
0.1
0.2
20.0
0.2
0.4
0.2
0.2
0.4
20.0
0.2
0.4
0.4
0.2
0.2
AVERAGE
RECOVERY
R(%)
84
90
88
92
85
82
*
82
83
106
95
99
86
100
104
87
89
100
*
87
97
88
*
105
100
86
*
84
84
91
S(R)
0.9
3.9
0.5
4.7
2.3
1.4
*
1.4
0.4
6.6
2.7
6.5
0.4
0.8
2.5
0.9
6.6
15.0
*
0.5
3.9
5.0
*
1.9
2.2
0.4
*
1.1
1.1
3.5
RPD
3.0
8.1
1.7
9.3
2.4
4.9
2.3
4.4
1.2
5.6
2.8
8.0
1.2
0.4
2.2
1.2
4.8
2.7
2.0
1.1
1.4
0.9
2.0
4.6
3.0
1.2
2.7
3.6
3.6
8.9
S(R)
RPD
 <
 *
Standard deviation of percent recovery.
Relative percent difference between duplicate spike determinations
Sample concentration below established method detection limit.
Spike concentration <10% of sample background concentration.
                                        78

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              TABLE 6.   PRECISION AND RECOVERY DATA IN SOLID MATRICES

                              EPA HAZARDOUS SOIL #884
ANALYTE
   SAMPLE    LOW+    AVERAGE
   CONC     SPIKE   RECOVERY
   pig/kg    mg/kg     R(%)    S(R)
RPD
HIGH""  AVERAGE
SPIKE RECOVERY
mg/kg   R(%)   S(R)
RPD

Ag
Al
As
B
Ba
Be
Ca
Cd
Co,
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Sn
Sr
Tl
V
Zn

1.1
5080
5.7
20.4
HI
0.66
85200
2
5.5
79.7
113
16500
<1.4
621
6.7
24400
343
5.3
195
15.6
595
145
6.1
<5
16.6
102
<4
16.7
131

20
20
20
100
20
20
-
20
20
20
20
-
10
500
10
500
20
20
500
20
500
20
20
20
20
100
20
20
20

98
*
95
93
98
97
-
93
96
87
110
—
92
121
113
*
*
88
102
. 100
106
88
83
79
91
84
92
104
103

0.7
*
5.4
2.7
71.4
0.7
_
0.7
3.5
28.8
16.2
_
2.5
1.3
3.5
*
*
5.3
2.2
1.8
13.4
51.8
3.9
14.7
34.6
9.6
4.8
4.2
31.2

1.0
7.2
10.6
5.3
22.2
2.0
_
1.0
7.7
16.5
4.4
_
.7.7
0.0
4.4
8.4
8.5
13.2
2.4
0.0
8.0
17.9
7.5
52.4
5.8
10.8
14.6
5.4
7.3

100
100
100
400
100
100
_
100
100
100
100
_
40
2000
40
2000
100
100
2000
100
2000
100
100
100
80
400
100
100
100

96
*
96
100
97
99
_
94
93
104
104
_
98
107
106
*
95
91
100
94
103
108
81
99
112
94
91
99
104

0.2
*
1.4
2.1
10.0
0.1
_
0.2
0.8
1.3
4.0
. —
0.0
0.9
0.6
*
11.0
1.4
1.5
1.5
3.2
15.6
1.9
0.7
8.7
2.5
1.5
0.8
7.2

0.6
5.4
3.6
5.5
1.0
0.2
_
0.4
2.1
1.1
4.2
— .
0.0
1.8
0.6
10.1
1.6
4.1
3.7
3.6
2.7
17.4
5.9
2.1
2.8
4.6
4.6
1.7
6.4
S(R)
RPD
 <
 *
Standard deviation of percent recovery.
Relative percent difference between duplicate spike determinations,
Sample concentration below established method detection limit.
Spike concentration <10% of sample background concentration.
Not spiked.
Equivalent
                                        79

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          TABLE 6.   PRECISION AND RECOVERY DATA IN SOLID MATRICES (Cont.)

                          EPA ELECTROPLATING SLUDGE #286
          SAMPLE    LOW"*"
          CONC     SPIKE
ANALYTE   mg/kg    mg/kg
 AVERAGE
RECOVERY
          S(R)
RPD
 HIGH"*" AVERAGE
SPIKE RECOVERY
mg/kg   R(%)   S(R)
RPD
Ag
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Sn
Sr
Tl
V
Zn
6
4980
32
210
39.8
0.32
48500
108
5.9
7580
806
31100
6.1
2390
9.1
1950
262
13.2
73400
456
9610
1420
<2
6.3
24.0
145
16
21.7
12500
20
20
20
100
20
20
-
20
20
20
20
-
10
500
10
500
20
20
500
20
500
20
20
20
20
100
20
20
20
96
*
94
113
0
96
-
98
93
*
*
-
90
75
101
110
*
92
*
*
*
*
76
86
87
90
89
95
*
0.2
*
1.3
2.0
6.8
0.2
-
2.5
2.9
*
*
-
2.5
8.3
2.8
2.0
*
2.1
*
*
*
*
0.9
9.0
4.0
8.1
4.6
1.2
*
0.4
4.4
0.8
1.6
0.3
0.5
-
0.8
5.7
0.7
1.5
-
4.0
4.0
0.5
0.8
1.8
2.9
1.7
0.4
2.9
2.1
3.3
16.6
2.7
8.1
5.3
1.0
0.8
100
100
100
400
100
100
-
100
100
100
100
-
40
2000
40
2000
100
100
2000
100
2000
100
100
100
100
400
100
100
100
93.2
*
97
98
0
100.68
-
96
93
*
94
-
97
94
106
108
91
92
*
88
114
*
75
103
92
93
92
96
*
0.1
*
0.7
1.9
1.6
0.7
. -
0.5
0.6
*
8.3
-
1.7
2.9
1.6
2.3
1.2
0.3
*
2.7
7.4
*
2.8
1.6
0.7
2.4
0.8
0.4
*
0.4
5.6
1.6
3.5
5.7
2.0
-
0.5
1.5
1.3
0.7
-
4.3
3.8
3.1
3.2
0.9
0.0
1.4
0.9
3.4
1.3
10.7
2.7
0.0
4.6
0.9
0.9
0.8
S(R)   Standard deviation of percent recovery.
RPD    Relative percent difference between duplicate spike determinations.
 <     Sample concentration below established method detection limit.
 *     Spike concentration <10% of sample background concentration.
       Not spiked.
 +     Equivalent
                                        80

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          TABLE 6.  PRECISION AND RECOVERY DATA  IN SOLID MATRICES (Cont.)

                              NBS 1645 RIVER SEDIMENT
ANALYTE
SAMPLE
CONC
 LOW"1"
SPIKE
mg/kg
                             AVERAGE
                            RECOVERY
                           S(R)
RPD
 HIGH"1" AVERAGE
SPIKE RECOVERY
rag/kg   R(%)   S(R)
                                                                             RPD
Ag
Al
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Sn
Sr
Tl
V
Zn
S(R)
RPD
1.6
5160
62.8
31.9
54.8
0.72
28000
9.7
9.4
28500
109
84800
3.1
452
3.7
6360
728
17.9
1020
36.2
553
707
22.8
6.7
309
782
<4
20.1
1640
20
20
20
100
20
20
-
20
20
20
20
-
10
500
10
500
20
20
500
20
500
20
20
20
20
100
20
20
20
92
*
89
116
95
101
_
100
98
*
115
_
99
98
101
*
*
97
92
94
102
*
86
103
*
91
90
89
*
Standard deviation of percent
Relative percent difference b'«
0,4
*
14.4
7.1
6.1
0.4
_
1.1
3.8
*
8.5
_
4.3
4.1
2.0
*
*
12.5
2.6
5.9
1.4
*
2.3
14.3
*
12.3
0.0
5.4
*
1.0
8.4
9.7
13.5
2.8
1.0
_
0.0
4.8
0.4
0.0
•^
7.7
2.0
0.7
1.8
3.5
18.5
0.0
4.0
0.9
0.8
0.0
27.1
1.0
3.0
0.0
5.8
1.8
100
100
100
400
100
100
_
100
100
100
100
_
40
2000
40
2000
100
100
2000
100
2000
100
100
100
100
400
100
100
100
96
*
97
95
98
103

101
98
*
102

96
106
108
93
97
98
97
100
100
103
88
98
101
96
95
98

0.3
*
2.9
0.6
1.2
1.4

0.7
0.9
*
1.8

0.7
1.4
1.3
2.7
12.4
0.6
1.1
1.1
0.8
5.9
0.6
3.1
7.9
3.3
1.3
0.7
*
0.9
2.4
5.0
1.5
1.3
3.9

1.8
1.8
0.7
1.0

1.0
2.3
3.0
1.0
2.2
0.0
1.7
1.5
1.6
0.4
0.9
7.6
2.7
2.6
4.0
0.0
1.1
recovery.
Jtween duplicate soike determinations.
                f  	..— — P . . w • -v • . v w Mwv*ii^i_|| U 14LS I  I V* IA VX* *J LS I IX Vi V4CUCI III I I I CL Lr
       Sample concentration below established method detection  limit.
       Spike concentration  <10% of sample background concentration.
       Not  spiked.
       Equivalent
                                        81

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TABLE 7.  DRINKING WATER 4X PRECONCENTRATION PRECISION AND RECOVERY DATA (1)
         SAMPLE     LOW
          CONC     SPIKE
ANALYTE   mg/L      mg/L
 AVERAGE
RECOVERY
          RSD(%)
 HIGH    AVERAGE
SPIKE   RECOVERY
 mg/L     R(%)    RSD(%)
Ag
AT
As
B
Ba
Be
Ca
Cd
Cr
Cu
Fe
Hg
K
Mg
Hn
Ho
Na
Ni
Pb
Sb
Se
Sr
Tl
V
Zn
<0.001
0.102
<0.004
0.022
0.037
<0.0002
32.6
<0.0006
<0.002
<0.001
<0.02
<0.003
2.09
7.49
0.002
<0.003
8.21
<0.002
<0.005
<0.004
<0.01
0.160
<0.008
<0.002
0.003
0.025
0.05
0.02
0.02
0.5
0.001
-
0.005
0.05
0.5
0.1
0.01
-
-
0.005
0.01
-
0.01
0.01
0.01
0.05
0.1
0.02
0.01
0.02
95
95
101
100
101
100
-
100
99
99
114
84
-
-
100
103
-
112
105
106
107
94
98
100
101
0.5
1.6
10.9
1.2
0.7
0.0
1.9
2.4
1.0
0.7
5.4
7.1
2.2
2.0
1.4
5.3
1.9
1.9
11.4
7.5
8.8
0.3
8.6
3.1
1.8
0.12
0.2
0.08
0.08
2.0
0.004
-
0.02
0.2
2.0
0.4
0.04
-
-
0.02
0.04
-
0.04
0.04
0.04
0.2
0.4
0.08
0.04
0.08
95
104
98
96
98
100
-
95
96
96
102
94
-
-
110
102
-
103
108
99
96
102
100
100
95
4.6
5.2
3.6
5.1
4.0
5.0
-
3.8
3.9
3.3
5.0
6.6
-
-
4.8
4.6
-
5.6
4.4
9.1
5.6
4.7
4.4
5.7
5.0
                                        82

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                    METHOD 200.8

DETERMINATION OF TRACE ELEMENTS IN WATERS AND WASTES
 BY INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY
                  Stephen E. Long
          Technology Applications,

                       and
Inc.
                Theodore D. Martin
            Inorganic Chemistry Branch
           Chemistry Research Division
                   Revision 4.4
                    April  1991
   ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
        OFFICE OF RESEARCH AND DEVELOPMENT
       U.S.  ENVIRONMENTAL PROTECTION AGENCY
              CINCINNATI, OHIO 45268
                        83


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                                 METHOD 200.8

             DETERMINATION OF TRACE ELEMENTS IN WATERS AND WASTES
               BY  INDUCTIVELY  COUPLED  PLASMA -  MASS  SPECTROMETRY
1.   SCOPE AND APPLICATION

     1.1  This method provides procedures for determination of dissolved
          elements in ground waters, surface waters and drinking water.  It
          may also be used for determination of total recoverable element
          concentrations in these waters as well as wastewaters, sludges and
          solid waste samples.

     1.2  Dissolved elements are determined after suitable filtration and acid
          preservation.  Acid digestion procedures are required prior to
          determination of total recoverable elements.  In order to reduce
          potential interferences, dissolved solids should not exceed
          0.2% (w/v) (Sect. 4.1.4).

     1.3  This method is applicable to the following elements:
              Element

              Aluminum   (Al)
              Antimony   (Sb)
              Arsenic    (As)
              Barium     (Ba)
              Beryllium  (Be)
              Cadmium    (Cd)
              Chromium   (Cr)
              Cobalt     (Co)
              Copper     (Cu)
              Lead       (Pb)
              Manganese  (Mn)
              Molybdenum (Mo)
              Nickel     (Ni)
              Selenium   (Se)
              Silver     (Ag)
              Thallium   (Tl)
              Thorium    (Th)
              Uranium    (U)
              Vanadium   (V)
              Zinc       (Zn)
Chemical Abstract Services
Registry Numbers (CASRN)
        7429-90-5
        7440-36-0
        7440-38-2
        7440-39-3
        7440-41-7
        7440-43-9
        7440-47-3
        7440-48-4
        7440-50-8
        7439-92-1
        7439-96-5
        7439-98-7
        7440-02-0
        7782-49-2
        7440-22-4
        7440-28-0
        7440-29-1
        7440-61-1
        7440-62-2
        7440-66-6
          Estimated instrument detection limits (IDLs) for these elements are
          listed in Table 1.  These are intended as a guide to instrumental
          limits typical of a system optimized for multielement determinations
          and employing commercial instrumentation and pneumatic nebulization
          sample introduction.  However, actual method detection limits  (MDLs)
                                      84

-------
          and linear working ranges will be dependent on the sample matrix,
          instrumentation and selected operating conditions.

     1.4  This method is suitable for the determination of silver in aqueous
          samples containing concentrations up to 0.1 mg/L.  For the analysis
          of wastewater samples containing higher concentrations of silver,
          succeeding smaller volume, well mixed sample aliquots must be
          prepared until the analysis solution contains < 0.1 mg/L silver.

     1.5  This method should be used by analysts experienced in the use of
          inductively coupled plasma mass spectrometry (ICP-MS), the
          interpretation of spectral and matrix interferences and procedures
          for their correction.  A minimum of six months experience with
          commercial instrumentation is recommended.

2.   SUMMARY OF METHOD

     2.1  The method describes the multi-element determination of trace
          elements by ICP-MS " .  Sample material in solution is introduced by
          pneumatic nebulization into a radiofrequency. plasma where energy
          transfer processes cause desolvation, atomization and ionization.
          The ions are extracted from the plasma through a differentially
          pumped vacuum interface and separated on the basis of their mass-to-
          charge ratio by a quadrupole mass spectrometer having a minimum
          resolution capability of 1 amu peak width at 5% peak height.   The
          ions transmitted through the quadrupole are registered by a con-
          tinuous dynode electron multiplier or Faraday detector and the ion
          information processed by a data handling system.   Interferences
          relating to the technique (Sect.  4) must be recognized and corrected
          for.  Such corrections must include compensation for isobaric
          elemental interferences and interferences from polyatomic ions
          derived from the plasma gas,  reagents or sample matrix.   Instrumen-
          tal drift as well  as suppressions or enhancements of instrument
          response caused by the sample matrix must be corrected for by the
          use of internal  standardization.

3.   DEFINITIONS

     3.1  DISSOLVED - Material  that will  pass through a 0.45 fj,m membrane
          filter assembly,  prior to sample  acidification.

     3.2  TOTAL RECOVERABLE  - The concentration of analyte  determined on an
          unfiltered sample  following treatment with hot dilute mineral  acid.
     3.3
INSTRUMENT DETECTION LIMIT (IDL) - The concentration equivalent of
the analyte signal, which is equal to three times the standard
deviation of the blank signal at the selected analytical  mass(es).
     3.4  METHOD DETECTION LIMIT (MDL)  - The minimum concentration of an
          analyte that can be identified,  measured and reported with 99%
          confidence that the analyte concentration is greater than zero.
                                      85

-------
3.5  LINEAR DYNAMIC RANGE (LDR) - The concentration range over which the
     analytical working curve remains linear.

3.6  LABORATORY REAGENT BLANK (LRB) (preparation blank) - An aliquot of
     reagent water that is treated exactly as a sample including exposure
     to all labware, equipment, solvents, reagents, and internal
     standards that are used with other samples.  The LRB is used to
     determine if method analytes or other interferences are present in
     the laboratory environment, the reagents or apparatus.

3.7  CALIBRATION BLANK - A volume of ASTM type I water acidified with the
     same acid matrix as is present in the calibration standards.

3.8  INTERNAL STANDARD - Pure analyte(s) added to a solution in known
     amount(s) and used to measure the relative responses of other method
     analytes that are components of the same solution.  The internal
     standard must be an analyte that is not a sample component.

3.9  STOCK STANDARD SOLUTION - A concentrated solution containing one or
     more analytes prepared in the laboratory using assayed reference
     compounds or purchased from a reputable commercial source.

3.10 CALIBRATION STANDARD (CAL) - A solution prepared from the stock
     standard solution(s)  which is used to calibrate the instrument
     response with respect to analyte concentration.

3.11 TUNING SOLUTION - A solution which is used to determine acceptable
     instrument performance prior to calibration and sample analyses.

3.12 LABORATORY FORTIFIED BLANK (LFB) - An aliquot of reagent water to
     which known quantities of the method analytes are added in the
     laboratory.  The LFB is analyzed exactly like a sample, and its
     purpose is to determine whether method performance is within
     accepted control limits.

3.13 LABORATORY FORTIFIED SAMPLE MATRIX  (LFM) - An aliquot of an
     environmental sample to which known quantities of the method analy-
     tes are added in the laboratory.  The LFM is analyzed exactly like a
     sample, and its purpose is to determine whether the sample matrix
     contributes bias to the analytical results.  The background concen-
     trations of the analytes  in the sample matrix must be determined in
     a separate aliquot and the measured values in the LFM corrected for
     the concentrations found.

3.14 QUALITY CONTROL SAMPLE (QCS) - A solution containing known
     concentrations of method  analytes which is used to fortify an
     aliquot of LRB matrix.  The QCS is obtained from a source external
     to the laboratory and is  used to check laboratory performance.
                                 86

-------
4.   INTERFERENCES

     4.1  Several interference sources may cause inaccuracies in the
          determination of trace elements by ICP-MS.  These are:

          4.1.1  Isobaric elemental interferences - Are caused by isotopes of
                 different elements which form singly or doubly charged ions
                 of the same nominal mass-to-charge ratio and which cannot be
                 resolved by the mass spectrometer in use.  All elements
                 determined by this method have, at a minimum, one isotope
                 free of isobaric elemental interference.  Of the analytical
                 isotopes recommended for use with this method (Table 4), only
                 molybdenum-98 (ruthenium) and selenium-82 (krypton) have
                 isobaric elemental interferences.  If alternative analytical
                 isotopes having higher natural abundance are selected in
                 order to achieve greater sensitivity, an isobaric
                 interference may occur.  All data obtained under such condi-
                 tions must be corrected by measuring the signal from another
                 isotope of the interfering element and subtracting the
                 appropriate signal ratio from the isotope of interest.  A
                 record of this correction process should be included with the
                 report of the data.  It should be noted that such corrections
                 will only be as accurate as the accuracy of the isotope ratio
                 used in the elemental equation for data calculations.
                 Relevant isotope ratios and instrument bias factors should be
                 established prior  to the application of any corrections.

          4.1.2  Abundance sensitivity - Is a property defining the degree to
                 which the wings; of a mass peak contribute to adjacent masses.
                 The abundance sensitivity is affected by ion energy and quad-
                 rupole operating pressure.  Wing overlap interferences may
                 result when a small ion peak is being measured adjacent to a
                 large one.  The potential for these  interferences should be
                 recognized and the spectrometer resolution adjusted to
                 minimize them.

          4.1.3  Isobaric polyatomic ion interferences - Are caused by ions
                 consisting of more than one atom which have the same nominal
                 mass-to-charge ratio as the isotope  of interest, and which
                 cannot be resolved by the mass spectrometer in use.  These
                 ions are commonly  formed  in the plasma or interface system
                 from support gases or sample components.  Most of the common
                 interferences have been identified , and these are listed in
                 Table 2 together with the method elements affected.  Such
                 interferences must be recognized, and when they cannot be
                 avoided by the selection  of alternative analytical isotopes,
                 appropriate corrections must be made to the data.  Equations
                 for the correction of data should be established at the time
                 of the analytical  run sequence as the polyatomic ion
                 interferences will be highly dependent on the sample matrix
                 and chosen instrument conditions.


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         4.1.4  Physical  interferences  -  Are  associated  with  the  physical
                processes which  govern  the  transport  of  sample  into  the
                plasma,  sample conversion processes in the  plasma, and the
                transmission  of  ions  through  the  plasma-mass  spectrometer
                interface.  These  interferences may result  in differences
                between  instrument responses  for  the  sample and the
                calibration standards.  Physical  interferences  may occur in
                the  transfer  of  solution  to the nebulizer (e.g.,  viscosity
                effects),  at  the point  of aerosol  formation and transport to
                the  plasma (e.g.,  surface tension), or during excitation and
                ionization processes  within the plasma itself.  High  levels
                of dissolved  solids in  the  sample  may contribute  deposits of
                material  on the  extraction  and/or  skimmer cones reducing the
                effective diameter of the orifices and therefore  ion
                transmission.  Dissolved  solids levels not  exceeding
                0.2% (w/v) have  been  recommended3  to reduce such effects.
                Internal  standardization  may  be effectively used  to
                compensate for many physical  interference effects4.   Internal
                standards  ideally  should  have similar analytical  behavior to
                the  elements  being determined.

         4.1.5   Memory interferences  -  Result when isotopes of  elements in a
                previous  sample  contribute  to the  signals measured in a new
                sample.   Memory  effects can result from  sample  deposition on
                the  sampler and  skimmer cones, and from  the buildup of sample
                material  in the  plasma torch and spray chamber.  The site
                where these effects occur is dependent on the element and can
                be minimized  by  flushing  the system with a  rinse blank
                between samples  (Sect. 7.6.3).  The possibility of memory
                interferences should  be recognized within an  analytical run
                and  suitable  rinse  times  should be used  to  reduce them.  The
                rinse times necessary for a particular element  should be
                estimated prior  to  analysis.  This may be achieved by
                aspirating a  standard containing elements corresponding to
                ten  times the upper end of the linear range for a normal
                sample analysis  period, followed by analysis of the rinse
                blank at designated intervals.  The length  of time required
                to reduce analyte  signals to within a factor of ten of the
                method detection limit, should be  noted.   Memory
                interferences may  also be assessed within an analytical run
                by using a minimum of three replicate integrations for data
                acquisition.  If the  integrated signal values drop
                consecutively, the analyst should be alerted to the
                possibility of a memory effect,  and should examine the
                analyte concentration in  the previous sample to identify if
                this was high.   If a memory interference  is  suspected, the
                sample should be reanalyzed after a long  rinse period.

5. SAFETY

   5.1  The toxicity or carcinogenicity of reagents used in this method  have
        not been fully established.  Each chemical should be regarded as a

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   5.2
potential health hazard and exposure to these compounds should be as
low as reasonably achievable.  Each laboratory is responsible for
maintaining a current awareness file of OSHA regulations regarding
the safe handling of the chemicals specified in this method '  .  A
reference file of material data handling sheets should also be
available to all personnel involved in the chemical analysis.

Analytical plasma sources emit radiofrequency radiation in addition
to intense UV radiation.  Suitable precautions should be taken to
protect personnel from such hazards.
6. APPARATUS AND EQUIPMENT

   6.1  INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETER

        6.1.1  Instrument capable of scanning the mass range 5-250 amu with
               a minimum resolution capability of 1 amu peak width at 5%
               peak height.  Instrument may be fitted with a conventional or
               extended dynamic range detection system.

        6.1.2  Argon gas supply (high-purity grade, 99.99%).

        6.1.3  A variable-speed peristaltic pump is required for solution
               delivery to the nebulizer.

        6.1.4  A mass-flow controller on the nebulizer gas supply is
               required.  A water-cooled spray chamber may be of benefit in
               reducing some types of interferences (e.g., from polyatomic
               oxide species).

        6.1.5  Operating conditions - Because of the diversity of instrument
               hardware, no detailed instrument operating conditions are
               provided.  The analyst is advised to follow the recommended
               operating conditions provided by the manufacturer.  It is the
               responsibility of  the analyst to verify that the instrument
               configuration and  operating conditions satisfy the analytical
               requirements and to maintain quality control data verifying
               instrument performance and analytical results.  Instrument
               operating conditions which were used to generate precision
               and  recovery data  for this method (Sect.  13) are included in
               Table 6.

        6.1.6   If  an electron multiplier detector  is being  used, precautions
               should  be taken, where necessary, to prevent exposure to  high
                ion  flux.   Otherwise changes  in instrument response or damage
               to  the  multiplier  may result.  Samples  having high
               concentrations of  elements beyond the linear range of the
                instrument  and with  isotopes  falling within  scanning windows
                should  be diluted  prior  to analysis.

    6.2  LABWARE  -  For  the  determination of trace levels  of  elements,
         contamination  and  loss  are  of prime  consideration.  Potential

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         contamination sources include improperly cleaned laboratory
         apparatus and general contamination within the laboratory
         environment from dust, etc.   A clean laboratory work area,
         designated for trace element sample handling must be used.   Sample
         containers can introduce positive and negative errors in the
         determination of trace elements by (1)  contributing contaminants
         through surface desorption or leaching,  (2)  depleting element con-
         centrations through adsorption processes.   All  reuseable labware
         (glass, quartz, polyethylene, Teflon,  etc.)  including the sample
         container should be cleaned  prior to use.   Labware may be soaked
         overnight and thoroughly washed with laboratory-grade detergent and
         water,  rinsed with water,  and soaked for four hours in a mixture of
         dilute  nitric and hydrochloric acid (1+2+9),  followed by rinsing
         with  water,  ASTM type I  water and oven  drying.

         NOTE:   Chromic acid must not be used for cleaning glassware.

         6.2.1   Glassware - Volumetric flasks, graduated cylinders,  funnels
                and centrifuge tubes.

         6.2.2   Assorted calibrated pipettes.

         6.2.3   Conical  Phillips  beakers,  250-mL  with  50-mm watch  glasses.
                Griffin beakers,  250-mL with 75-mm  watch glasses.

         6.2.4   Storage bottles - Narrow mouth bottles,  Teflon  FEP
                (fluorinated ethylene  propylene)  with  Tefzel  ETFE  (ethylene
                tetrafluorethylene) screw closure,  125-mL  and  250-mL
                capacities.

   6.3   SAMPLE  PROCESSING  EQUIPMENT

         6.3.1   Air Displacement  Pipetter  -  Digital pipet  system capable  of
                delivering  volumes  from 10 to 2500  /zL with  an  assortment  of
                high  quality disposable pipet tips.

         6.3.2   Balance  - Analytical,  capable of  accurately weighing to
                0.1 mg.

         6.3.3   Hot Plate -  (Corning PC100 or equivalent).

         6.3.4   Centrifuge -  Steel cabinet with guard bowl, electric timer
                and brake.

         6.3.5   Drying Oven  - Gravity convection oven with thermostat!c
                control capable of maintaining 105°C ± 5°C.

7. REAGENTS AND CONSUMABLE MATERIALS

   7.1  Reagents may contain elemental impurities that might affect the
        integrity of analytical data.  Owing to the high sensitivity of ICP-
                                    90

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    MS, high-purity reagents should be used whenever possible.  All
    acids used for this method must be of ultra high-purity grade.
    Suitable acids are available from a number of manufacturers or may
    be prepared by sub-boiling distillation.  Nitric acid is preferred
    for ICP-MS in order to minimize polyatomic ion interferences.
    Several polyatomic ion interferences result when hydrochloric acid
    is used (Table 2), however, it should be noted that hydrochloric
    acid  is required to maintain stability in solutions containing
    antimony and silver.  When hydrochloric acid is used, corrections
    for the chloride polyatomic ion interferences must be applied to all
    data.

    7.1.1  Nitric acid, concentrated  (sp.gr. 1.41).

    7.1.2  Nitric acid  (1+1) - Add 500 ml cone, nitric acid to  400 ml of
           ASTM type  I water and dilute to 1 L.

    7.1.3  Nitric acid  (1+9) - Add 100 ml cone, nitric acid to  400 ml of
           ASTM type  I water and dilute to 1 L.

    7.1.4 Hydrochloric acid, concentrated  (sp.gr.  1.19).

    7.1.5 Hydrochloric acid  (1+1) -  Add  500 ml cone, hydrochloric acid
           to  400 ml  of ASTM type  I water and dilute to  1  L.

    7.1.6 Hydrochloric acid  (1+4) -  Add  200 mL cone, hydrochloric acid
           to  400 ml  of ASTM type  I water and dilute to  1  L.

    7.1.7 Ammonium hydroxide,  concentrated  (sp.gr.  0.902).

    7.1.8 Tartaric acid  (CASRN 87-69-4).

7.2 WATER -  For all  sample preparation and  dilutions, ASTM type I water
     (ASTM D1193)  is required.   Suitable  water may be prepared by passing
    distilled water through a  mixed  bed  of  anion  and cation exchange
     resins.

7.3  STANDARD STOCK SOLUTIONS - May be purchased from a  reputable
     commercial source or  prepared from ultra high-purity grade chemicals
     or metals (99.99 - 99.999% pure).  All  salts  should be dried for 1  h
     at 105°C, unless otherwise specified.  (CAUTION: Many metal salts
     are extremely toxic if inhaled or swallowed.   Wash  hands thoroughly
     after handling).   Stock solutions should be stored  in Teflon
     bottles.   The following procedures may  be used for  preparing stan-
     dard stock solutions:

     NOTE: Some metals, particularly those which form surface oxides
     require cleaning prior to being weighed.  This may be achieved by
     pickling the surface of the metal in acid.   An amount in excess of
     the desired weight should be pickled repeatedly, rinsed with water,
     dried and weighed until the desired weight is achieved.


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 7.3.1   Aluminum solution,  stock 1  ml = 1000 jug Al:  Pickle aluminum
        metal  in warm (1+1)  HC1  to  an exact  weight of 0.100 g.
        Dissolve in  10 ml cone.  HC1  and 2  mL cone, nitric acid,
        heating  to effect solution.   Continue heating until  volume  is
        reduced  to 4 mL.   Cool  and  add 4 ml  ASTM type I  water.   Heat
        until  the volume  is  reduced  to 2 mL.   Cool and dilute to
        100  mL with  ASTM  type  I  water.

 7.3.2   Antimony solution,  stock 1 mL = 1000 jug Sb:  Dissolve 0.100  g
        antimony powder in  2 mL  (1+1)  nitric acid and 0.5 mL cone.
        hydrochloric acid,  heating to effect solution.   Cool, add
        20 mL  ASTM type I water  and  0.15 g tartaric  acid.   Warm  the
        solution to  dissolve the white  precipitate.   Cool  and dilute
        to 100 mL with  ASTM  type I water.

 7.3.3   Arsenic  solution, stock  1 mL =  1000  /zg As: Dissolve 0.1320  g
        As203 in  a mixture of 50 mL  ASTM type I water and 1 mL cone.
        ammonium hydroxide.  Heat gently to  dissolve.  Cool  and
        acidify  the  solution with 2  mL  cone,  nitric  acid.   Dilute to
        100  mL with  ASTM type  I  water.

 7.3.4   Barium solution, stock 1 mL  =  1000 p,g Ba: Dissolve 0.1437 g
        BaC03  in  a solution mixture  of 10 mL ASTM type I  water and
        2 mL cone, nitric acid.  Heat and  stir  to effect  solution and
        degassing.   Dilute to  100 mL with ASTM  type  I water.
7.3.5
7.3.6
7.3.7
       Beryllium  solution,  stock  1 mL =  1000 ng  Be:  Dissolve
       1.965 g  BeS04.4HpO (DO NOT DRY)  in 50 mL  ASTM Type I water.
       Add  1 mL cone, nitric  acid.  Dilute to  100 mL with ASTM type
       I water.
       Bismuth solution, stock 1 mL = 1000 p,g  Bi:  Dissolve  0.1115  g
       Bi203 in  5 mL cone,  nitric acid.   Heat to effect solution.
       Cool and dilute to  100 mL with ASTM type  I water.
       Cadmium solution, stock 1 mL = 1000 /xg  Cd:  Pickle cadmium
       metal in (1+9) nitric acid to an exact weight of 0.100 g.
       Dissolve in 5 mL (1+1) nitric acid, heating to effect
       solution.  Cool and dilute to 100 mL with ASTM type I water.

7.3.8  Chromium solution, stock 1 mL = 1000 ng Cr: Dissolve
       0.1923 g Cr03 in a solution mixture of 10  mL ASTM type I
       water and 1 mL cone, nitric acid.  Dilute to 100 mL with ASTM
       type I water.

7.3.9  Cobalt solution, stock 1 mL = 1000 ;ug Co: Pickle cobalt
       metal in (1+9) nitric acid to an exact weight of 0.100 g.
       Dissolve in 5 mL (1+1) nitric acid, heating to effect
       solution.  Cool and dilute to 100 mL with  ASTM type I water.
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7.3.10  Copper solution, stock 1 ml = 1000 /zg Cu: Pickle copper
        metal in (1+9) nitric acid to an exact weight of 0.100 g.
        Dissolve in 5 ml (1+1) nitric acid, heating to effect
        solution.  Cool and dilute to 100 ml with ASTM type I water.

7.3.11  Indium solution, stock 1 ml = 1000 jug In: Pickle indium
        metal in (1+1) nitric acid to an exact weight of 0.100 g.
        Dissolve in 10 ml (1+1) nitric acid, heating to effect
        solution.  Cool and dilute to 100 ml with ASTM type I water.

7.3.12  Lead solution, stock 1 ml = 1000 jug Pb: Dissolve 0.1599  g
        PbN03 in 5 mL (1+1)  nitric acid.  Dilute to 100 ml with ASTM
        type I water.

7.3.13  Magnesium solution, stock 1 ml = 1000 ng Mg: Dissolve
        0.1658 g MgO  in 10 ml  (1+1) nitric acid, heating to effect
        solution.  Cool and dilute to 100 ml with ASTM type I water.
7.3.14
 7.3.15
 7.3.16
 7.3.17
Manganese solution, stock 1 ml = 1000 jug Mn: Pickle
manganese flake in (1+9) nitric acid to an exact weight of
0.100 g.  Dissolve in 5 ml (1+1) nitric acid, heating to
effect solution.  Cool and dilute to 100 ml with ASTM type I
water.

Molybdenum solution, stock 1 ml = 1000 /xg Mo: Dissolve
0.1500 g Mo03 in a solution mixture of 10 ml ASTM type I
water and 1 ml cone, ammonium hydroxide., heating to effect
solution.  Cool and dilute to 100 ml with ASTM type I water.

Nickel solution, stock 1 ml = 1000 /jg  Ni: Dissolve 0.100 g
nickel powder in 5 ml cone, nitric acid, heating to effect
solution.  Cool and dilute to 100 ml with ASTM type I water.
Scandium solution, stock 1 ml = 1000 jug  Sc:  Dissolve
0.1534 g Sc203 in 5 ml (1+1)  nitric acid, heating to effect
solution.  Cool  and dilute to 100 ml with ASTM type I water.
 7.3.18  Selenium solution,  stock 1  ml = 1000 jug Se: Dissolve
         0.1405 g Se02  in  20 ml ASTM type  I water.   Dilute  to  100 ml
         with ASTM type I  water.

 7.3.19  Silver solution,  stock 1 ml = 1000 ng Ag: Dissolve 0.100 g
         silver metal  in 5 ml (1+1)  nitric acid, heating to effect
         solution.  Cool and dilute  to 100 ml with ASTM type I water.
         Store in dark container.

 7.3.20  Terbium solution, stock 1 ml = 1000 jug Tb: Dissolve 0.1176 g
         Tb,07 in  5 ml  cone, nitric  acid,  heating to effect  solution.
         Cool and dilute to 100 ml with ASTM type I water.
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7.4
 7.3.21   Thallium solution,  stock 1  mL  =  1000  p,g Tl:  Dissolve
         0.1303  g T1NO, in a solution mixture  of  10 mL ASTM type  I
         water and 1  ml cone,  nitric acid.   Dilute to  100  ml  with ASTM
         type I  water.

 7.3.22   Thorium solution, stock  1 ml = 1000 /ig Th: Dissolve  0.2380 g
         Th(N03)4.4H,0 (DO NOT  DRY)  in 20  ml  ASTM type  I  water.
         Dilute  to 100 ml with ASTM  type  I water.

 7.3.23   Uranium solution, stock  1 ml = 1000 jug U: Dissolve 0.2110  g
         UO§(N03)2.6H,0 (DO NOT DRY)  in  20 ml ASTM type I water and
         dilute  to 100 mL with ASTM  type  I water.

 7.3.24   Vanadium  solution, stock 1  mL  =  1000  jug  V: Pickle vanadium
         metal in  (1+9) nitric acid  to  an exact weight of  0.100 g.
         Dissolve  in 5 mL (1+1) nitric  acid, heating to effect
         solution.  Cool  and dilute  to  100 mL  with ASTM type  I water.

7.3.25  Yttrium solution, stock 1 mL = 1000 jug Y: Dissolve 0.1270  g
        Y20,  in  5 mL  (1+1) nitric  acid, heating to effect  solution.
        Cool  and dilute to 100 mL with ASTM type I water.

7.3.26  Zinc solution, stock 1 mL = 1000 jug Zn:  Pickle zinc  metal  in
         (1+9) nitric acid to an exact weight of 0.100 g.  Dissolve in
        5 mL (1+1) nitric acid,  heating to effect solution.   Cool and
        dilute  to 100 mL  with  ASTM type I water.

 MULTIELEMENT STOCK STANDARD SOLUTIONS  -  Care must be taken  in the
 preparation  of multielement stock standards that the elements are
 compatible and  stable.   Originating element stocks  should be*checked
 for the presence of impurities  which might influence the accuracy of
 the standard.   Freshly prepared standards should be  transferred to
 acid cleaned,  not previously  used FEP  fluorocarbon  bottles  for
 storage and  monitored periodically for stability.  The  following
 combinations of elements are  suggested:
       Standard Solution A
       Aluminum
       Antimony
       Arsenic
       Beryl 1i urn
       Cadmium
       Chromium
       Cobalt
       Copper
       Lead
                Manganese
                Molybdenum
                Nickel
                Selenium
                Thallium
                Thorium
                Uranium
                Vanadium
                Zinc
Standard Solution B

       Barium
       Silver
    Multielement  stock  standard  solutions A  and  B  (1 mL  =  10  /Ltg)  may be
    prepared by diluting  1 mL  of each  single element stock in the
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    combination  list to  100 ml with ASTM type  I water containing  1%
    (v/v)  nitric acid.

    7.4.1   Preparation of calibration  standards -  fresh multielement
            calibration standards  should be  prepared  every  two weeks or
            as  needed.  Dilute each of  the stock multielement standard
            solutions A and B to levels appropriate to the  operating
            range of the  instrument using ASTM  type I water containing
            1%  (v/v) nitric acid.  The  element  concentrations in  the
            standards  should be  sufficiently high to  produce good
            measurement precision  and to accurately define  the  slope of
            the response  curve.  Concentrations of  200 jug/L are
            suggested.   If the direct addition  procedure  is being used
            (Method A,  Sect. 9.2), add  internal standards  (Sect.  7.5) to
            the calibration standards and  store in  Teflon  bottles.
            Calibration  standards  should be  verified  initially  using  a
            quality control sample (Sect.  7.8).

7.5  INTERNAL STANDARDS STOCK  SOLUTION, 1  mL =  100  pg.   Dilute 10 mL of
     scandium,  yttrium,  indium,  terbium and  bismuth stock standards
     (Sect. 7.3) to 100 mL with  ASTM type  I  water,  and  store in a Teflon
     bottle.  Use this solution  concentrate  for addition  to blanks,
     calibration standards and samples, or dilute by an  appropriate
     amount using 1% (v/v) nitric acid, if the  internal  standards are
     being added by peristaltic pump (Method B, Sect. 9.2). a

7.6  BLANKS - Three types of blanks are required  for this method.  A
     calibration blank is used to establish the analytical  calibration
     curve, the  laboratory reagent blank is used  to  assess possible
     contamination  from the sample preparation procedure and to assess
     spectral background  and the  rinse blank is used to flush the
     instrument  between samples in order to reduce memory  interferences.

     7.6.1  Calibration blank - Consists of 1% (v/v) nitric acid  in ASTM
            type I  water.   If the direct addition  procedure (Method A,
            Sect. 9.2),  is being  used  add internal standards.

     7.6.2  Laboratory reagent blank (LRB)  - Must  contain  all the
            reagents in  the same  volumes as used in  processing the
            samples.  The LRB must be  carried  through the  entire  sample
            digestion and preparation  scheme.  If  the direct addition
            procedure (Method A,  Sect. 9.2)  is being used,  add internal
            standards to  the solution  after preparation is complete.

     7.6.3 Rinse blank  - Consists of  2%  (v/v) nitric acid in ASTM type  I
            water.

 7.7  TUNING SOLUTION - This solution is used for instrument tuning and
     mass  calibration prior to  analysis.  The  solution is  prepared by
     mixing beryllium, magnesium, cobalt, indium and lead  stock  solutions
      (Sect. 7.3) in 1%  (v/v) nitric acid to produce  a concentration of


                                  95

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      100 ng/L of each element.
      solution.
                                    Internal  standards  are not  added to this
 7.8
 7.9
        QUALITY CONTROL SAMPLE  (QCS) - The QCS should be obtained from a
        source outside the  laboratory.  Dilute an appropriate aliquot of
        analytes  (concentrations not to exceed 1000 jug/L),  in 1%  (v/v)
        nitric acid.  If the direct addition procedure (Method A, Sect. 9.2)
        is being  used, add  internal standards after dilution, mix and store
        in a Teflon bottle.

        LABORATORY FORTIFIED BLANK (LFB) - To an aliquot of LRB, add
        aliquots  from multielement stock standards A and B  (Sect. 7.4) to
        produce a final concentration of 100 fj.g/1 for each  analyte.  The
        LFB must  be carried through the entire sample digestion and
        preparation scheme.  If the direct addition procedure (Method A,
        Sect. 9.2) is being used, add internal standards to this solution
        after preparation has been completed.

8. SAMPLE COLLECTION. PRESERVATION AND STORAGE

   8.1  Prior to sample collection, consideration should be given to the
        type of data required so that appropriate preservation and
        pretreatment steps can be taken.   Filtration,  acid preservation,
        etc., should be performed at the time of sample collection or as
        soon thereafter as practically possible.

        For the determination of dissolved elements,  the sample  should be
        filtered through a 0.45-jum membrane filter.   Use a portion of the
        sample to rinse the filter assembly,  discard  and then collect the
        required volume of filtrate.   Acidify the filtrate with  (1+1) nitric
        acid immediately following filtration to  pH <  2.

        For the determination of total  recoverable elements in aqueous
        samples,  acidify with (1+1) nitric acid  at the time of collection to
        pH < 2 (normally,  3 mL of (1+1)  nitric acid per liter of sample  is
        sufficient for most ambient and  drinking  water samples).   The sample
        should not be filtered prior  to  analysis.

        NOTE:  Samples that cannot be  acid  preserved at the  time  of
        collection because of sampling  limitations or  transport
        restrictions,  should be  acidified  with nitric  acid  to  pH  < 2  upon
        receipt in the laboratory.  Following  acidification,  the  sample
        should be  held for 16 h  before withdrawing an  aliquot  for  sample
        processing.

   8.4  Solid  samples  usually require no preservation  prior  to analysis
        other  than storage at  4°C.
8.2
8.3
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9. CALIBRATION AND STANDARDIZATION

   9.1  CALIBRATION - Demonstration and documentation of acceptable initial
        calibration is required before any samples are analyzed and is
        required periodically throughout sample analysis as dictated by
        results of continuing calibration checks.  After initial calibration
        is successful, a calibration check is required at the beginning and
        end of each period during which analyses are performed, and at
        requisite intervals.

        9.1.1  Initiate proper operating configuration of instrument and
               data system.  Allow a period of not less than 30 min for the
               instrument to warm up.  During this process conduct mass
               calibration and resolution checks using the tuning solution.
               Resolution at low mass is indicated by magnesium isotopes
               24,25,26.  Resolution at high mass is indicated by lead
               isotopes 206,207,208.  For good performance adjust
               spectrometer resolution to produce a peak width of
               approximately 0.75 amu at 5% peak height.  Adjust mass
               calibration if it has shifted by more than 0.1 amu from unit
               mass.

        9.1.2  Instrument stability must be demonstrated by running the
               tuning solution  (Sect. 7.7) a minimum of five times with
               resulting relative standard deviations of absolute signals
               for all analytes of less than 5%.

        9.1.3  Prior  to initial calibration, set up proper instrument
               software routines for quantitative analysis.  The instrument
               must be calibrated for the analytes to be determined using
               the calibration  blank  (Sect. 7.6.1) and calibration standards
               A  and  B  (Sect. 7.4.1) prepared  at one or more concentration
               levels.  A minimum of three replicate integrations are
               required for data acquisition.  Use the average  of the
                integrations for instrument calibration and data reporting.

        9.1.4  The rinse blank  should be used  to flush the system between
                solution changes for  blanks, standards and  samples.  Allow
                sufficient  rinse time to  remove traces of the previous  sample
                or a minimum of  1 min.   Solutions should be aspirated  for 30
                sec prior to the acquisition of data  to  allow equilibrium to
                be established.

    9.2  INTERNAL  STANDARDIZATION -  Internal standardization must be  used in
         all  analyses  to correct for  instrument drift  and physical
         interferences.  A  list  of acceptable  internal  standards is  provided
         in Table  3.   For  full.mass  range scans,  a minimum  of three  internal
         standards must  be  used.  Procedures described  in this  method  for
         general  application,  detail  the use of five  internal standards;
         scandium, yttrium,  indium,  terbium  and bismuth.  These were  used to
         generate  the precision  and  recovery data attached  to this method.
         Internal  standards must be  present  in  all  samples,  standards  and

                                     97

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          blanks  at identical  levels.   This  may  be  achieved  by  directly  adding
          an  aliquot of the  internal  standards to the  CAL  standard,  blank  or
          sample  solution  (Method  A,  Sect. 9.2), or alternatively  by mixing
          with  the  solution  prior  to  nebulization using  a  second channel of
          the peristaltic  pump and a  mixing  coil (Method B,  Sect.  9.2).  The
          concentration of the internal  standard should  be sufficiently  high
          that  good precision  is obtained  in the measurement of the  isotope
          used  for  data correction and  to minimize  the possibility of
          correction errors  if the internal  standard is  naturally  present  in
          the sample.   A concentration  of 200 p,g/L  of  each internal  standard
          is  recommended.  Internal  standards should be added to blanks,
          samples and  standards in a  like manner, so that  dilution effects
          resulting from the addition may be disregarded.

    9.3   INSTRUMENT PERFORMANCE - Check the performance of  the instrument and
          verify the calibration using  data  gathered from  analyses of
          calibration  blanks,.calibration standards and  the  quality  control
          sample  (QCS).

          9.3.1  After the calibration  has been established, it must be
                initially verified for all  analytes by  analyzing  the QCS
                 (Sect.  7.8).   If  measurements exceed ±  10%  of  the
                established QCS value, the  analysis should  be  terminated, the
                source  of the problem  identified and corrected, the
                instrument recalibrated and the calibration reverified before
                continuing analyses.

          9.3.2  To  verify that the instrument is properly calibrated on a
                continuing basis,  run the calibration blank and calibration
                standards as  surrogate samples after every ten analyses.  The
                results of the analyses of the standards will   indicate
                whether the calibration remains valid.  If the indicated
                concentration of  any analyte deviates from the true
                concentration by more than  10%,  reanalyze the  standard.  If
                the analyte is again outside the 10% limit,  the instrument
                must  be recalibrated and the previous ten samples reanalyzed.
                The instrument responses from the calibration  check may be
                used  for recalibration purposes.   If the sample matrix is
                responsible for the calibration  drift,  it is recommended that
                the previous ten samples are reanalyzed in groups of five
                between calibration checks to prevent a similar drift
                situation from occurring.

10. QUALITY CONTROL

    10.1 Each laboratory using this method is required to operate a formal
         quality control (QC)  program.   The  minimum requirements  of this
         program consist of an initial  demonstration of laboratory
         capability, and the analysis of laboratory reagent  blanks,  fortified
         blanks and samples  as a continuing  check  on performance.   The
                                     98

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10,2
     laboratory is required to maintain performance records that define
     the quality of the data thus generated.

10.2 INITIAL DEMONSTRATION OF PERFORMANCE

     10.2.1 The initial demonstration of performance is used to
            characterize instrument performance (method detection limits
            and linear calibration ranges) for analyses conducted by this
            method.

         .2 Method detection limits (MDL) should be established for all
            analytes, using reagent water (blank) fortified at a
            concentration of two to five times the estimated detection
            limit7.  To determine MDL values,  take seven replicate
            aliquots of the fortified reagent water and process through
            the entire analytical method.  Perform all calculations
            defined in the method and report the concentration values  in
            the appropriate units.  Calculate the MDL as follows:

            MDL =  (t)  x (S)

            where, t =   Student's t value for a 99% confidence level  and
                         a  standard deviation estimate with n-1 degrees
                         of freedom  [t  =  3.14 for  seven replicates].

                   S =  standard deviation of the  replicate  analyses.

            MDLs  should be  determined  every six  months  or  whenever  a
             significant change in  background  or  instrument response is
            expected  (e.g.,  detector  change).

      10.2.3 Linear calibration ranges  - Linear calibration ranges are
             primarily  detector limited.  The  upper limit of the linear
             calibration range should be established for each  analyte  by
             determining the signal  responses  from a minimum of three
             different  concentration  standards, one of which is close  to
             the upper  limit of the linear range.  Care should be taken to
             avoid potential damage to the detector during  this process.
             The linear calibration range which may be used for the
             analysis of samples should be judged by the analyst from the
             resulting data.  Linear calibration  ranges should be
             determined every six months or whenever a significant change
             in instrument response is expected (e.g., detector change).

 10.3 ASSESSING LABORATORY PERFORMANCE - REAGENT AND FORTIFIED BLANKS

      10.3.1 Laboratory reagent blank (LRB) - The laboratory must analyze
             at least one LRB  (Sect. 7.6.2) with each set of samples.  LRB
             data  are used to  assess contamination from the laboratory
             environment and to characterize spectral background  from the
             reagents  used  in  sample processing.   If an analyte value  in
             the reagent blank exceeds  its determined MDL,  then laboratory

                                  99

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             or reagent contamination should  be suspected.   Any determined
             source of contamination  should be  corrected  and the samples
             reanalyzed.

      10.3.2  Laboratory fortified  blank (LFB) - The  laboratory  must
             analyze at least  one  LFB (Sect.  7.9) with  each  batch  of
             samples.   Calculate accuracy  as  percent recovery (Sect.
             10.4.2)   If the recovery of any  analyte falls outside the
             control  limits  (Sect.  10.3.3), that analyte  is  judged out  of
             control,  and the  source  of the problem  should be identified
             and resolved before continuing analyses.

      10.3.3  Until  sufficient  LFB data  become available (usually a minimum
             of 20  to  30  analyses), the  laboratory should assess
             laboratory performance against recovery limits  of  85-115%.
             When sufficient internal performance data becomes  available,
             develop control limits from the percent mean recovery (x)  and
             the standard deviation (S) of the mean  recovery.   These data
             are used  to  establish upper and lower control limits  as
             follows:

                  UPPER CONTROL LIMIT = x + 3S
                  LOWER CONTROL LIMIT = x - 3S

            After each five to ten new recovery measurements, new control
            limits should be calculated using only the most recent twenty
            to 30 data points.

10.4 ASSESSING ANALYTE RECOVERY -  LABORATORY  FORTIFIED SAMPLE MATRIX

     10.4.1 The laboratory must add a known  amount  of analyte to a
            minimum of 10% of the  routine  samples  or one  sample per
            sample set, whichever  is  greater.   Ideally for water samples,
            the analyte concentration should  be the  same  as  that used in
            the LFB (Sect. 10.3.2).   For solid  samples, the  concentration
            added  should be 50 mg/kg  equivalent (100 p.g/1 in the
            analysis solution).  Over time, samples  from  all routine
            sample sources should  be  fortified.

     10.4.2 Calculate the percent  recovery for  each  analyte, corrected
            for background concentrations  measured in the unfortified
            sample,  and compare these values  to the  control  limits
            established in Sect. 10.3.3 for the analyses  of  LFBs.
            Recovery calculations  are not  required if the concentration
            of the  analyte added is less than 10% of the  sample
            background concentration.   Percent  recovery may  be  calculated
            in units  appropriate to the matrix,  using the following
           equation:
             R =
                     - c
x 100
                                100

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               where,   R  = percent recovery
                        Cs = fortified sample concentration
                        C  = sample background concentration
                        s  = concentration equivalent of
                             fortifier added to sample.

        10.4.3 If recovery of any analyte falls outside the designated range
               and laboratory performance for that analyte is shown to be in
               control (Sect. 10.3), the recovery problem encountered with
               the fortified sample is judged to be matrix related, not
               system related.  The result for that analyte in the
               unfortified sample must be labelled "suspect/matrix" to
               inform the data user that the results are suspect due to
               matrix effects.

   10.5 INTERNAL STANDARDS RESPONSES - The analyst is expected to monitor
        the responses from the internal standards throughout the sample set
        being analyzed.   Ratios of the internal standards responses against
        each other should also be monitored  routinely.  This information may
        be used to detect potential problems caused by mass dependent drift,
        errors incurred  in adding the  internal standards or increases in the
        concentrations of individual  internal standards caused by background
        contributions from the sample.  The  absolute response of any one
        internal standard should not deviate more than 60-125% of the
        original response in the calibration blank.  If deviations greater
        than this are observed, use the following test procedure:

        10.5.1 Flush the instrument with the rinse blank and monitor the
               responses in  the calibration  blank.   If the responses of the
               internal  standards are  now within the limit, take a fresh
               aliquot of the  sample,  dilute by a further factor of two, add
               the  internal  standards  and reanalyze.

         10.5.2  If test  (Sect.  10.5.1)  is not satisfied, or  if  it is a blank
               or calibration  standard that  is out of  limits,  terminate the
                analysis, and determine the cause of  the drift.   Possible
               causes of drift may  be a partially blocked sampling cone or  a
                change in the tuning condition  of the instrument.

11.  PROCEDURE

    11.1 SAMPLE  PREPARATION - DISSOLVED ELEMENTS

         11.1.1  For  determination  of dissolved elements in drinking water,
                ground and surface waters,  take a  100 mL  aliquot  of the
                filtered acid preserved sample,  and  add 1  mL of concentrated
                nitric acid.  If the direct addition  procedure  (Method A)  is
                being used,  add internal  standards  and mix.   The  sample  is
                now ready for analysis.  Allowance  for sample dilution  should
                be made in the calculations.
                                     101

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            NOTE: If a precipitate is formed during acidification,
            transport or storage, the sample aliquot must be treated
            using the procedure in Sect. 11.2.1 prior to analysis.

11.2 SAMPLE PREPARATION - TOTAL RECOVERABLE ELEMENTS

     11.2.1 For determination of total  recoverable elements in water or
            wastewater, take a 100 mL aliquot from a well  mixed,  acid
            preserved sample containing not more than 0.25% (w/v)  total
            solids and transfer to a 250-mL Griffin beaker (if total
            solids are greater than 0.25% reduce the size  of the  aliquot
            by a proportionate amount).   Add 1  mL of cone,  nitric  acid
            and 0.5  mL cone, hydrochloric acid.   Heat on a hot plate at
            85°C until  the volume has been reduced to approximately 20
            mL,  ensuring that the sample does not boil.  A spare  beaker
            containing 20 mL of water can be used as a guage.   (NOTE:
            Adjust the temperature control  of the hot plate such that  an
            uncovered beaker containing  50 mL of water located in  the
            center of the hot plate can  be maintained at a  temperature no
            higher than 85°C.   Evaporation time  for 100  mL  of  sample  at
            85°C is  approximately 2 h with the  rate of evaporation
            increasing  rapidly as  the sample volume approaches 20  mL).
            Cover  the beaker with  a watch glass  and reflux  for 30  min.
            Slight boiling  may occur  but  vigorous  boiling  should   be
            avoided.  Allow to cool and  quantitatively transfer to either
            a  50-mL  volumetric flask  or  50-mL class  A stoppered graduated
            cylinder.   Dilute  to volume with ASTM  type I water and mix
            Centrifuge  the  sample  or  allow  to stand  overnight  to separate
            insoluble material.  Prior to  analysis,  pipette 20 mL  into a
            50-mL  volumetric flask, dilute  to volume with ASTM type I
           water  and mix.   If the  direct addition  procedure (Method A
           Sect.  9.2)  is being used, add  internal  standards and mix.
           The sample  is now  ready for analysis. Because the  stability
           of diluted  samples  cannot be  fully characterized, all
           analyses should be  performed as soon as possible after the
           completed preparation.

    11.2.2 For determination of total recoverable elements in solid
           samples (sludge, soils, and sediments), mix the sample
           thoroughly to achieve homogeneity and weigh accurately a
           1.0 ±  0.01 g portion of the sample.   Transfer to a 250-mL
           Phillips beaker.  Add 4 mL (1+1) nitric acid  and 10 mL (1+4)
           HC1.  Cover with a watch glass, and  reflux the sample  on a
           hot plate for 30 min.  Very slight boiling may occur,
           however,  vigorous boiling must be avoided to  prevent the loss
           of the HCl-HpO azeotrope.   (NOTE:  Adjust the  temperature
           control of the hot plate such that an uncovered Griffin
           beaker containing 50 mL of water located in the center  of the
           hot plate can be maintained  at a temperature  of approximately
           but no higher than 85°C).  Allow the  sample to  cool,   and
           quantitatively transfer to a  100-mL  volumetric  flask.   Dilute
                               102

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            to  volume with  ASTM  type  I water  and mix.  Centrifuge  the
            sample  or allow to stand  overnight  to  separate  insoluble
            material.   Prior to  analysis,  pipette  10 ml  into  a  50-mL
            volumetric  flask and dilute  to volume  with ASTM type  I water.
            If  the  direct addition  procedure  (Method A,  Sect. 9.2) is
            being used,  add internal  standards  and mix.   The  sample is
            now ready for analysis.   Because  the effects of various
            matrices on the stability of diluted samples cannot be
            characterized,  all analyses  should  be  performed as  soon as
            possible after the completed preparation.

            NOTE:  Determine the percent solids in the  sample for use  in
            calculations and for reporting data on a dry weight basis.

11.3 For every  new  or  unusual matrix, it is highly recommended  that a
     semi-quantitative  analysis  be  carried out  to  screen for  high element
     concentrations.  Information gained from this may  be used  to prevent
     potential  damage  to the detector during sample analysis  and  to
     identify elements  which may be higher than the linear range.  Matrix
     screening  may  be  carried out by using intelligent  software,  if
     available, or  by  diluting the  sample by a factor  of 500  and  analyz-
     ing in a semi-quantitative  mode.  The sample  should also be  screened
     for background levels of all elements chosen  for  use as  internal
     standards  in order to prevent bias in the calculation of the
     analytical data.

11.4 Initiate instrument operating configuration.   Tune and calibrate the
     instrument for the analytes of  interest (Sect. 9).

11.5 Establish instrument  software run procedures for quantitative
     analysis.    For all sample analyses, a minimum of three replicate
     integrations are required for data acquisition.   Discard any
     integrations which are  considered to be statistical outliers  and use
     the average of the integrations for data reporting.

11.6 All masses which might  affect data quality must be monitored  during
     the analytical run.   As a minimum, those masses prescribed in Table
     4 must be monitored in  the  same scan as is used for the collection
     of the data.  This  information  should be used to correct the  data
     for identified interferences.

11.7 The rinse blank should  be  used  to  flush the  system between samples.
     Allow  sufficient  time to remove traces  of the previous  sample or a
     minimum of  one minute.  Samples should  be aspirated for 30  sec prior
     to the collection  of  data.

11.8 Samples having concentrations higher than the established linear
     dynamic range  should  be diluted into range and reanalyzed.   The
     sample should  first  be analyzed for  the trace elements  in the
     sample, protecting the detector from the  high concentration
     elements,  if  necessary, by the  selection  of  appropriate scanning
     windows.   The  sample  should then be  diluted  for the determination  of

                                 103

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         the remaining elements.  Alternatively, the dynamic range may be
         adjusted by selecting an alternative isotope of lower natural
         abundance, provided quality control data for that isotope have been
         established.  The dynamic range must not be adjusted by altering
         instrument conditions to an uncharacterized state.

12. CALCULATIONS

    12.1 Elemental equations recommended for sample data calculations are
         listed in Table 5.  Sample data should be reported in units of
         for aqueous samples or mg/kg dry weight for solid samples.   Do not
         report element concentrations below the determined MDL.

    12.2 For data values less than ten,  two significant figures should be
         used for reporting element concentrations.   For data values greater
         than or equal  to ten,  three significant figures should be used.

    12.3 Reported values should be calibration  blank subtracted.   For aqueous
         samples prepared by total  recoverable  procedure (Sect.  11.2.1)
         multiply solution concentrations by the dilution factor  1.25.   For
         solid  samples  prepared by total  recoverable procedure (Sect.
         11.2.2),  multiply solution concentrations  (/ig/L in the analysis
         solution)  by the dilution  factor 0.5.   If  additional  dilutions were
         made to any samples, the  appropriate factor should be applied to the
         calculated  sample concentrations.

    12.4 Data values should be  corrected  for instrument  drift  or  sample
         matrix  induced  interferences  by  the application  of internal
         standardization.   Corrections for  characterized  spectral
         interferences should be applied  to  the  data.  Chloride interference
         corrections should be  made  on all  samples,  regardless of  the
         addition  of hydrochloric acid, as  the chloride  ion  is a common
         constituent of environmental  samples.

    12.5  If an element has  more than one monitored isotope, examination of
         the  concentration  calculated for each isotope, or  the isotope
         ratios, will provide useful information for the  analyst in detecting
         a possible  spectral interference.   Consideration should therefore be
         given to both primary and secondary  isotopes in  the evaluation of
         the  element concentration.  In some cases, secondary isotopes may be
         less sensitive or more prone to interferences than the primary
         recommended isotopes, therefore differences between the results do
         not necessarily indicate a problem with data calculated for the
         primary isotopes.

   12.6 The QC data obtained during the analyses provide an indication of
        the quality of the sample data and should be provided with the
        sample results.
                                   104

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13.  PRECISION AND ACCURACY

    13.1 Instrument operating conditions used for single laboratory testing
         of the method are summarized in Table 6.  Total recoverable MDLs
         determined using the procedure described in Sect. 10.2.2, are listed
         in Table 7.

    13.2 Data obtained from single laboratory testing of the method are
         summarized in Table 8 for five water samples representing drinking
         water, surface water, ground water and waste effluent.  Samples were
         prepared using the procedure described in Sect. 11.2.1.  For each
         matrix, five replicates were analyzed and the average of the
         replicates used for determining the sample background concentration
         for each element.  Two further pairs of duplicates were fortified at
         different concentration levels.  For each method element, the sample
         background concentration, mean percent recovery, the standard
         deviation of the percent recovery and the relative percent
         difference between the duplicate fortified samples are listed in
         Tables.

    13.3 Data obtained from single laboratory testing of the method are
         summarized in Table 9 for three solid samples consisting of SRM
         1645 River Sediment, EPA Hazardous Soil and EPA Electroplating
         Sludge.  Samples were prepared using the procedure described  in
         Sect.  11.2.2.   For each method element, the sample background
         concentration,  mean percent recovery, the standard deviation  of the
         percent recovery and the relative percent difference  between  the
         duplicate  fortified samples were determined as for Sect.  13.2.

 14. REFERENCES

    1.   A.  L.  Gray and  A. R. Date, Analyst  108  1033  (1983).

    2.   R.  S.  Houk et al. Anal  Chetn.  52 2283  (1980).

    3.   R.  S.  Houk,  Anal. Chem.  58  97A (1986).

    4.   J.  J.  Thompson  and  R.  S. Houk, Appl.  Spec.  41  801  (1987).

    5.    "OSHA Safety and Health Standards,  General  Industry," (29 CFR 1910),
         Occupational  Safety and Health Administration,  OSHA  2206,  revised
         January 1976.

    6.    "Proposed OSHA  Safety  and  Health  Standards,  Laboratories,"
          Occupational  Safety and Health Administration,  Federal
          Register,  July  24,  1986.

     7.    Code of Federal Regulations 40,  Ch.  1,  Pt.  136 Appendix B.
                                      105

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         TABLE 1: ESTIMATED INSTRUMENT DETECTION LIMITS
       ELEMENT
    RECOMMENDED
  ANALYTICAL MASS
                                              ESTIMATED  IDL
                                                 (M9/L)
       Aluminum
       Antimony
       Arsenic
       Barium
       Beryl 1i urn
       Cadmium
       Chromium
       Cobalt
       Copper
       Lead
       Manganese
       Molybdenum
       Nickel
       Selenium
       Silver
       Thallium
       Thorium
       Uranium
       Vanadium
       Zinc
         27
        121
         75
        137
          9
        111
         52
         59
         63
206.207,208
         55
         98
         60
         82
        107
        205
        232
        238
         51
         66
0.05
0.08
0.9
0.5
0.
0.
0.07
0.03
0.03
0.08
0.1
0.1
0.2
5
0.05
0.09
0.03
0.02
0.02
0.2
Instrument detection limits (3a) estimated from seven replicate
integrations of the blank (1% v/v nitric acid) following calibration of
the instrument with three replicate integrations of a multi-element
standard.
                                106

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      TABLE 2: COMMON MOLECULAR ION INTERFERENCES IN ICP-MS
BACKGROUND MOLECULAR IONS
Molecular Ion
NH*
OH+
OH2+
C2+
CN+
C0+
N2*
N2H*
N0+
NOH+
°2+
02H+
36ArH+
38ArH+
40ArH+
C02*
C02H+
ArC^.ArO*
ArN+
ArNH+
ArO+
ArOH*
40Ar36Ar+
40Ar38Ar+
40Ar2+
Mass
15
17
18
24
26
28
28
29
30
31
32
33
37
39
41
44
45
52
54
55
56
57
76
78
80
Element Interference8















Sc
Cr
Cr
Mn


Se
Se
Se
method elements or internal standards affected by the molecular ions,
                                    107

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                      TABLE 2 (Continued).
MATRIX MOLECULAR IONS
CHLORIDE
Molecular Ion
35C10*
35C10H*
37C10*
37C10H*
Ar35Cl*
Ar37Cl*
SULPHATE
Molecular Ion
32SO*
SOH*
SO*
34SOH*
S02*, S2*
Ar32S*
Ar34S*
PHOSPHATE
Molecular Ion
PO*
POH*
P02*
ArP*
GROUP I, II METALS
Molecular Ion
ArNa*
ArK*
ArCa*
MATRIX OXIDES*
Molecular Ion
TiO
ZrO
MoO


Mass
51
52
53
54
75
77

Mass
48
49
50
51
64
72
74

Mass
47
48
63
71

Mass
63
79
80

Masses
62-66
106-112
108-116


Element Interference
V
Cr
Cr
Cr
As
Se

Element Interference


V,Cr
7 •
V
Zn



Element Interference


Cu


Element Interference
Cu



Element Interference
Ni,Cu,Zn
Ag,Cd
Cd
Oxide interferences will normally be very small and will only impact the
method elements when present at relatively high concentrations. Some
examples of matrix oxides are listed of which the analyst should be aware,
It is recommended that Ti and Zr isotopes are monitored in solid waste
samples, which are likely to contain high levels of these elements. Mo is
monitored as a method analyte.

                                   108

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         TABLE 3: INTERNAL STANDARDS AND LIMITATIONS OF USE
     Internal Standard

        6Lithium
         Scandium
         Yttrium
         Rhodium
         Indium
         Terbium
         Holmium
         Lutetium
         Bismuth
Mass

  6
 45
 89
103
115
159
165
175
209
  Possible Limitation
polyatomic ion interference
         a,b

isobaric interference by Sn
a May be present in environmental samples.
b In some ^instruments Yttrium may form measurable amounts of Y0+ (105  amu)
   and YOH*  (106  amu).  If  this  is the  case,  care  should be taken  in  the  use
   of the cadmium elemental  correction equation.

   Internal  standards recommended for  use with this method  are shown in  bold
   face.  Preparation procedures for these are included in section 7.3.
                                   109

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           TABLE 4: RECOMMENDED ANALYTICAL ISOTOPES AND ADDITIONAL
                        MASSES WHICH MUST BE  MONITORED
      Isotope

        27
        121.123
        75
        135.137
        9
        106.108.111.114
        52,53
        59
        63,65
        206.207.208
        55
        95,97,98
        60,62
        77,82
        107.109
        203.205
        232
        238
        51
        66,67,68

        83
        99
        105
        118
Element of Interest

    Aluminum
    Antimony
    Arsenic
    Barium
    Beryl 1i urn
    Cadmium
    Chromium
    Cobalt
    Copper
    Lead
    Manganese
    Molybdenum
    Nickel
    Selenium
    Silver
    Thallium
    Thorium
    Uranium
    Vanadium
    Zinc

    Krypton
    Ruthenium
    Palladium
    Tin
NOTE: Isotopes recommended for analytical determination are underlined.
                                      110

-------
TABLE 5: RECOMMENDED ELEMENTAL EQUATIONS FOR DATA CALCULATIONS
El ement
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Elemental Equation
(1.000)(27C)
(1.000)(121C)
(1.000)(75C)-(3.127)[(77C)-(0.815)(82C)]
(1.000)(137C)
(1.000)(9C)
(1.000)(111C)-(1.073)[(108C)-(0.712)(106C)]
(1.000)(52C)
(1.000)(59C)
(1.000)(63C)
(1.000)(206C)+(1.000)(207C)+(1.000)(208C)
(1.000)(55C)
(1.000){98C)-(0.146)("C)
(1.000)(60C)
(1.000)(82C)
(1.000)(107C)
(1.000)(205C)
(1.000)(232C)
(1.000)(238C)
(l.qpO)(51C)-(3.l27)[(53C)-(O.H3)(52C)]
(1.000)(66C)
Note


(1)


(2)
(3)


(4)

(5)

(6)




(7)

                                                          Cont.
                                 Ill

-------
                         TABLE 5 (Continued)
 INTERNAL STANDARDS

 Element      Elemental Equation

  B1          (1.000)(209C)

              (1.000)(115C)-(0.016)(118C)
In

Sc

Tb

Y
                                                          Note
(8)
              (1.000)(45C)

              (1.000)(159C)

              (1.000)(89C)
 C  - calibration blank subtracted counts at specified mass.
(1) - correction for chloride interference with adjustment for
      Se77. ArCl 75/77 ratio may be determined from the reagent
      blank.
(2) - correction for MoO interference. An additional isobaric
      elemental correction should be made if palladium is present.
(3) - in 0.4% v/v HC1, the background from C10H will normally be
      small. However the contribution may be estimated from the
      reagent blank.
(4) - allowance for isotopic variability of lead isotopes.
(5) - isobaric elemental correction for ruthenium.
(6) - some argon supplies contain krypton as an impurity. Selenium
    is corrected for Kr82 by background subtraction.
(7) - correction for chloride interference with adjustment for
      Cr53. CIO 51/53 ratio may be determined from the reagent
      blank.
(8) - isobaric elemental correction for tin.
                                 112

-------
        TABLE 6: INSTRUMENT OPERATING CONDITIONS
             FOR PRECISION AND RECOVERY DATA
Instrument
Plasma forward power
Coolant flow rate
Auxiliary flow rate
Nebulizer flow rate
Solution uptake rate
Spray chamber temperature
VG PlasmaQuad Type I
1.35 kW
13.5 L/min
0.6 L/min
0.78 L/min
0.6 mL/min
15°C
Data Acquisition

Detector mode
Rep!icate i ntegrati ons
Mass range
Dwell time
Number of MCA channels
Number of scan sweeps
Total acquisition time
Pulse counting
3
8 - 240 amu
320 MS
2048
85
3 minutes per sample
                             113

-------
 TABLE 7: TOTAL RECOVERABLE METHOD DETECTION LIMITS
                RECOMMENDED
                              MDL*
ELEMENT
ANALYTICAL MASS
AQUEOUS
M9/L
SOLIDS
mg/kg
Aluminum
Antimony
Arsenic
Barium
Beryl1i urn
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Molybdenum
Nickel
Selenium
Silver
Thallium
Thorium
Uranium
Vanadium
Zinc
         27
        121
         75
        137
          9
        111
         52
         59
         63
206,207,208
         55
         98
         60
         82
        107
        205
        232
        238
         51
         66
1.0
0.4
1.4
0.8
0.3
0.5
0.9
0.09
0.5
0.6
0.1
0.3
0.5
7.9
0.1
0.3
0.1
0.1
2.5
1.8
0.4
0.2
0.6
0.4
0.1
0.2
0.4
0.04
0.
0.
0.05
0.1
0.2
3.2
0.05
0.1
0.05
0.05
1.0
0.7
,2
.3
  MDL concentrations are computed for original  matrix with
 allowance for sample dilution during preparation.
                           114

-------
      TABLE 8 :  PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES

                           DRINKING WATER


Element

Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Samp! e Low
Concn. Spike
(ad/Li (in /I)
175
<0.4
<1.4
43.8
<0.3
<0.5
<0.9
0.11
3.6
0.87
0.96
1.9
1.9
<7.9
<0.1
<0.3
<0.1
0.23
<2.5
5.2
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%}
115.8
99.1
99.7
94.8
113.5
97.0
111.0
94.4
101.8
97.8
96.9
99.4
100.2
99.0
100.7
97.5
109.0
110.7
101.4
103.4

S(R)

5.9
0.7
0.8
3.9
0.4
2.8
3.5
0.4
8.8
2.0
1.8
1.6
5.7
1.8
1.5
0.4
0.7
1.4
0.1
3.3
High
RPD Spike
(UQ/L)
0.4
2.0
2.2
5.8
0.9
8.3
9.0
1.1
17.4
2.8
4.7
3.4
13.5
5.3
4.2
1.0
1.8
3.5
0.4
7.7
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
Average
Recovery
R m
102.7
100.8
102.5
95.6
111.0
101.5
99.5
93.6
91.6
99.0
95.8
98.6
95.2
93.5
99.0
98.5
106.0
107.8
97.5
96.4

S(R)

1.6
0.7
1.1
0.8
0.7
0.4
0.1
0.5
0.3
0.8
0.6
0.4
0.5
3.5
0.4
1.7
1.4
0.7
0.7
0.5

RPD

1.1
2.0
2.9
1.7
1.8
1.0
0.2
1.4
0.3
2.2
1.8
1.0
1.3
10.7
1.0
4.9
3.8
1.9
2.1
1.0
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations,
 <    Sample concentration below established method detection limit.
                                     115

-------
    TABLE 8 : PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES (Cent).

                              WELL WATER
Element
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample Low
Concn. Spike
(uq/L) (UQ/L)
34.3
0.46
<1.4
106
<0.3
1.6
<0.9
2.4
37.4
3.5
2770
2.1
11.4
<7.9
<0.1
<0.3
<0.1
1.8
<2.5
554
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%)
100.1
98.4
110.0
95.4
104.5
88.6
111.0
100.6
104.3
95.2
*
103.8
116.5
127.3
99.2
93.9
103.0
106.0
105.3
*
S(R)
3.9
0.9
6.4
3.9
0.4
1.7
0.0
1.0
5.1
2.5
*
1.1
6.3
8.4
0.4
0.1
0.7
1.1
0.8
*
High
RPD Spike
(UQ/L)
0.8
1.9
16.4
3.3
1.0
3.8
0.0
1.6
1.5
1.5
1.8
1.6
6.5
18.7
1.0
0.0
1.9
1.6
2.1
1.2
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
Average
Recovery
R (%)
102.6
102.5
101.3
104.9
101.4
98.6
103.5
104.1
100.6
99.5
*
102.9
99.6
101.3
101.5
100.4
104.5
109.7
105.8
102.1
S(R)
1.1
0.7
0.2
1.0
1.2
0.6
0.4
0.4
0.8
1.4
*
0.7
0.3
0.2
1.4
1.8
1.8
2.5
0.2
5.5
RPD
1.3
1.9
0.5
1.6
3.3
1.6
1.0
0.9
1.5
3.9
0.7
1.9
0.0
0.5
3.9
5.0
4.8
6.3
0.5
3.2
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations.
 <    Sample concentration below established method detection limit.
 *    Spike concentration <10% of sample background concentration.
                                      116

-------
     TABLE 8 : PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES (Cont).

                               POND WATER


El ement

Al
Sb
As
Ba
Be ,
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample Low
Concn. Spike
(IM/L) (UQ/l)
610
<0.4
<1.4
28.7
<0.3
<0.5
2.0
0.79
5.4
1.9
617
0.98
2.5
<7.9
0.12
<0.3
0.19
0.30
3.5
6.8
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R m
*
101.1
100.8
102.1
109.1
106.6
107.0
101.6
107.5
108.4
*
104.2
102.0
102.7
102.5
108.5
93.1
107.0
96.1
99.8

S(R)

*
1.1
2.0
1.8
0.4
3.2
1.0
1.1
1.4
1.5
*
1.4
2.3
5.6
0.8
3.2
3.5
2.8
5.2
1.7
High
RPD Spike
faa/LV
1.7
2.9
5.6
2.4
0.9
8.3
1.6
2.7
1.9
3.2
1.1
3.5
4.7
15.4
2.1
8.3
10.5
7.3
14.2
3.7
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
Average
Recovery
R (%)
78.2
101.5
96.8
102.9
114.4
105.8
100. 0
101.7
98.1
106.1
139.0
104.0
102.5
105.5
105.2
105.0
93.9
107.2
101.5
100.1

S(R)

9.2
3.0
0.9
3.7
3.9
2.8
1.4
1.8
2.5
0.0
11.1
2.1
2.1
1.4
2.7
2.8
1.6
1.8
0.2
2.8
•i''
RPD

5.5
8.4
2.6
9.0
9.6
7.6
3.9
4.9
6.8
0.0
4.0
5.7
5.7
3.8
7.1
7.6
4.8
4.7
0.5
7.7
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations.
 <    Sample concentration below established method detection limit.
 *    Spike concentration <10% of sample background concentration.
                                      117

-------
    TABLE 8 :  PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES (Cont).

                     SEWAGE TREATMENT PRIMARY EFFLUENT


El ement

Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Ho
Ni
Se
Ag
Tl
Th
U
V
Zn
Samp! e Low
Concn. Spike
(UQ/L) (UQ/L)
1150
1.5
<1.4
202
<0.3
9.2
128
13.4
171
17.8
199
136
84.0
<7.9
10.9
<0.3
0.11
0.71
<2.5
163
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R m
*
95.7
104.2
79.2
110.5
101.2
*
95.1
*
95.7
*
*
88.4
112.0
97.1
97.5
15.4
109.4
90.9
85.8

S(R)

*
0.4
4.5
9.9
1.8
1.3
*
2.7
*
3.8
*
*
16.3
10.9
0.7
0.4
1.8
1.8
0.9
3.3
High
RPD Spike
(UQ/l)
3.5
0.9
12.3
2.5
4.5
0.0
1.5
2.2
2.4
1.1
1.5
1.4
4.1
27.5
1.5
1.0
30.3
4.3
0.6
0.5
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
Average
Recovery
R m
100.0
104.5
101.5
108.6
106.4
102.3
102.1
99.1
105.2
102.7
103.4
105.7
98.0
108.8
102.6
102.0
29.3
109.3
99.4
102.0

S(R)

13.8
0.7
0.7
4.6
0.4
0.4
1.7
1.1
7.1
1.1
2.1
2.4
0.9
3.0
1.4
0.0
0.8
0.7
2.1
1.5

RPD

1.5
1.9
2.0
5.5
0.9
0.9
0.4
2.7
0.7
2.5
0.7
2.1
0.0
7.8
3.7
0.0
8.2
1.8
6.0
1.9
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations.
 <    Sample concentration below established method detection limit.
 *    Spike concentration <10% of sample background concentration.
                                      118

-------
     TABLE 8 :  PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES (Cont).

                            INDUSTRIAL EFFLUENT
Element
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample Low
Concn. Spike
(«q/L) (UQ/L)
44.7
2990
<1.4
100
<0.3
10.1
171
1.3
101
294
154
1370
17.3
15.0
<0. 1
<0.3
0.29
0.17
<2.5
43.4
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%)
98.8
*
75.1
96.7
103.5
106.5
*
90.5
*
*
*
*
107.4
129.5
91.8
90.5
109.6
104.8
74.9
85.0
S(R)
8.7
*
1.8
5.5
1.8
4.4
*
3.2
*
*
*
*
7.4
9.3
0.6
1.8
1.2
2.5
0.1
4.0
High
RPD Spike
(UQ/L)
5.7
0.3
6.7
3.4
4.8
2.4
0.0
8.7
0.9
2.6
2.8
1.4
5.0
15.1
1.7
5.5
2.7
6.6
0.3
0.6
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
Average
Recovery
R (%)
90.4
*
75.0
102.9
100.0
97.4
127.7
90.5
92.5
108.4
103.6
*
88.2
118.3
87.0
98.3
108.7
109.3
72.0
97.6
S(R)
2.1
*
0.0
1.1
0.0
1.1
2.4
0.4
2.0
2.1
3.7
*
0.7
1.9
4.9
1.0
0.0
0.4
0.0
1.0
RPD
2.2
0.0
0.0
0.7
0.0
2.8
1.7
1.3
1.6
0.0
1.6
0.7
1.0
3.6
16.1
2.8
0.0
0.9
0.0
0.4
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations.
 <    Sample concentration below established method detection limit.
 *    Spike concentration <10% of sample background concentration.
                                     119

-------
         TABLE 9 : PRECISION AND RECOVERY DATA IN SOLID MATRICES

                         EPA HAZARDOUS SOIL #884
El ement
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample
Concn.
(mq/kq)
5170
5.4
8.8
113
0.6
1.8
83.5
7.1
115
152
370
4.8
19.2
<3.2
1.1
0.24
1.0
1.1
17.8
128
Low+
Spike
mq/kq)
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
Average High+ Average
Recovery S(R) RPD Spike Recovery S(R) RPD
R (%} (ma/ka) R (%)
* * 100 * *
69.8 2.5 4.7 100 70.4 1.8 6.5
104.7 5.4 9.1 100 102.2 2.2 5.4
54.9 63.6 18.6 100 91.0 9.8 0.5
100.1 0.6 1.5 100 102.9 0.4 1.0
97.3 1.0 1.4 100 101.7 0.4 1.0
86.7 16.1 8.3 100 105.5 1.3 0.0
98.8 1.2 1.9 100 102.9 0.7 1.8
86.3 13.8 3.4 100 102.5 4.2 4.6
85.0 45.0 13.9 100 151.7 25.7 23.7
* * 12.7 100 85.2 10.4 2.2
95.4 1.5 2.9 100 95.2 0.7 2.0
101.7 3.8 1.0 100 102.3 0.8 0.8
79.5 7.4 26.4 100 100.7 9.4 26.5
96.1 0.6 0.5 100 94.8 0.8 2.3
94.3 1.1 3.1 100 97.9 1.0 2.9
69.8 0.6 1.3 100 76.0 2.2 7.9
100.1 0.2 0.0 100 102.9 0.0 0.0
109.2 4.2 2.3 100 106.7 1.3 2.4
87.0 27.7 5.5 100 113.4 12.9 14.1
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations.
 <    Sample concentration below established method detection limit.
 *    Spike concentration <10% of sample background concentration.
      Not determined.
 +    Equivalent.
                                      120

-------
TABLE 9 : PRECISION AND RECOVERY DATA IN SOLID MATRICES (Cont).

                   NBS 1645 RIVER SEDIMENT


Sample Low+
Element Concn. Spike

Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
S(R)
RPD
(mq/kq)(mq/kq)
5060
21.8
67.2
54.4
0.59
8.3
29100
7.9
112
742
717
17.1
41.8
<3.2
1.8
1.2
0.90
0.79
21.8
1780
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
Average
Recovery
R (%)
*
73.9
104.3
105.6
88.8
92.9
*
97.6
121.0
*
*
89.8
103.7
108.3
94.8
91.2
91.3
95.6
91.8
*

S(R)

*
6.5
13.0
4.9
0.2
0.4
*
1.3
9.1
*
*
8.1
6.5
14.3
1.6
1.3
0.9
1.8
4.6
*
High+
RPD Spike
(mq/kq)
_
9.3
7.6
2.8
0.5
0.0
-
2.6
1.5
-
-
12.0
4.8
37.4
4.3
3.6
2.6
5.0
5.7
—
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Average
Recovery
R m
*
81.2
107.3
98.6
87.9
95.7
*
103.1
105.2
-
-
98.4
102.2
93.9
96.2
94.4
92.3
98.5
100.7
*

S(R)

*
1.5
2.1
2.2
0.1
1.4
*
0.0
2.2
-
-
0.7
0.8
5.0
0.7
0:4
0.9
1.2
0.6
*

RPD

_
3.9
2.9
3.9
0.2
3.9
-
0.0
1.8
-
-
0.9
0.0
15.1
1.9
1.3
2.8
3.5
0.8
—
Standard deviation of percent recovery.
Relative percent
difference between duplicate
spike determinations.
Sample concentration below established method detection limit.
Spike concentration <10% of sample background concentration.
Not determined.
Equivalent.
                                121

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     TABLE 9 : PRECISION AND RECOVERY DATA IN SOLID MATRICES (Cont).

                     EPA ELECTROPLATING SLUDGE #286
Element
AT
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Hn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample Low+
Concn. Spike
(mq/kq) mq/kq)
5110
8.4
41.8
27.3
0.25
112
7980
4.1
740
1480
295
13.3
450
3.5
5.9
1.9
3.6
2.4
21.1
13300
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
Average
Recovery
R m
*
55.4
91.0
1.8
92.0
85.0
*
89.2
*
*
*
82.9
*
89.7
89.8
96.9
91.5
107.7
105.6
*
S(R)
*
1.5
2.3
7.1
0.9
5.2
*
1.8
*
*
*
1.2
*
3.7
2.1
0.9
1.3
2.0
1.8
*
High+
RPD Spike
(mq/kq)

4.1
1.7
8.3
2.7
1.6
-
4.6
6.0
-
-
1.3
6.8
4.2
4.6
2.4
3.2
4.6
2.1
-
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Average
Recovery
R m
*
61.0
94.2
0
93.4
88.5
*
88.7
61.7
*
_
89.2
83.0
91.0
85.1
98.9
97.4
109.6
97.4
*
S(R)
*
0.2
0.8
1.5
0.3
0.8
*
1.5
20.4
*
_
0.4
10.0
6.0
0.4
0.9
0.7
0.7
1.1
*
RPD

0.9
1.5
10.0
0.9
0.5
-
4.6
5.4
-
_
1.0
4.5
18.0
1.1
2.4
2.0
1.8
2.5
-
S(R)  Standard deviation of percent recovery.
RPD   Relative percent difference between duplicate spike determinations,
 <    Sample concentration below established method detection limit.
 *    Spike concentration <10% of sample background concentration.
      Not determined.
 +    Equivalent.
                                      122

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                             METHOD 200.9

      DETERMINATION OF TRACE ELEMENTS BY STABILIZED TEMPERATURE
            GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY
John T. Creed, Theodore D. Martin, Larry B. Lobring and James W. O'Dell
                       Inorganic  Chemistry  Branch
                      Chemistry Research Division
                              Revision 1.2
                               April  1991
               ENVIRONMENTAL  MONITORING  SYSTEMS  LABORATORY
                   OFFICE OF RESEARCH AND DEVELOPMENT
                  U.S. ENVIRONMENTAL PROTECTION AGENCY
                         CINCINNATI, OHIO 45268
                                   123

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                                 METHOD 200.9

           DETERMINATION OF TRACE  ELEMENTS  BY STABILIZED  TEMPERATURE
                      GRAPHITE FURNACE ATOMIC ABSORPTION


1.   SCOPE AND APPLICATION

     1.1  This method provides procedures for the determination of dissolved
          and total recoverable elements in ground water, surface water,
          drinking water and wastewater.  This method is also applicable to
          total recoverable elements in sediment, sludges, biological tissues,
          and solid waste samples.

     1.2  Dissolved elements are determined after suitable filtration and acid
          preservation.   Acid digestion procedures are required prior to the
          determination  of total  recoverable elements.  Appropriate digestion
          procedures for biological  tissues should be utilized prior to sample
          analysis.

     1.3  This method is applicable  to the  determination  of the following
          elements by stabilized temperature graphite furnace atomic
          absorption spectrometry  (STGFAA).

              Element             Chemical Abstract Services
                                  Registry Numbers (CASRN)

              Aluminum   (Al)               7429-90-5
              Antimony   (Sb)               7440-36-0
              Arsenic    (As)               7440-38-2
              Beryllium   (Be)               7440-41-7
              Cadmium    (Cd)               7440-43-9
              Chromium   (Cr)               7440-47-3
              Cobalt     (Co)               7440-48-4
              Copper     (Cu)               7440-50-8
              Iron       (Fe)               7439-89-6
              Lead       (Pb)               7439-92-1
              Manganese   (Mn)               7439-96-5
              Nickel      (Ni)               7440-02-0
              Selenium   (Se)               7782-49-2
              Silver     (Ag)               7440-22-4
              Thallium   (Tl)               7440-28-0
              Tin         (Sn)               7440-31-5
              Zinc       (Zn)               7440-66-6

               NOTE:   Method detection  limit  and  instrumental  operating
               conditions  for  the  applicable  elements  are  listed  in Table 2.
               These  are  intended  as a  guide  to instrumental  detection  limits
               typical of  a  system optimized  for  the element  employing
               commercial  instrumentation.  However, actual method detection
               limits  and  linear working ranges will be dependent on  the


                                     124

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               sample matrix,  instrumentation  and  selected  operating
               conditions.

     1.4  The sensitivity and  limited linear dynamic range  (LDR)  of GFAA often
          implies the need to  dilute a sample  prior to the  analysis.  The
          actual  magnitude of  the dilution as  well  as the cleanliness of the
          labware used to perform the dilution can dramatically influence the
          quality of the analytical  results.  Therefore,  samples  types
          requiring large dilutions  should be  analyzed by an alternative
          analytical method which has a larger LDR or which is inherently less
          sensitive than GFAA.

     1.5  This method should be used by analysts experienced in the use of
          GFAA.

2.   SUMMARY OF METHOD

     2.1  This method describes the determination of applicable elements by
          stabilized temperature platform graphite furnace  atomic absorption
          (STPGFAA).  In STPGFAA the sample (and the matrix modifier, if
          required) is first pipetted onto the platform or  a device which
          provides delayed atomization.  The sample is then dried at a
          relatively low temperature (~120°C) to avoid spattering.  Once
          dried, the sample is normally pretreated in a char or ashing step
          which is designed to minimize the interference effects caused by the
          concomitant sample matrix.  After the char step the furnace is
          allowed to cool prior to atomization.  The atomization cycle is
          characterized by rapid heating of the furnace to  a temperature where
          the metal  (analyte)  is atomized from the pyrolytic graphite surface.
          The resulting atomic cloud absorbs the element specific atomic
          emission produced by a hollow cathode lamp (HCL)  or a electrode!ess
          discharge  lamp (EDL).  Because the resulting absorbance usually has
          a  nonspecific component associated with the actual analyte
          absorbance, an instrumental background correction device  is
          necessary  to subtract from the total signal the component which is
          nonspecific to the  analyte.  In the absence of interferences, the
          background corrected absorbance is directly related to the
          concentration of the analyte.   Interferences relating to  STPGFAA
          (Sect. 4)  must be recognized and  corrected.  Instrumental  drift  as
          well as  suppressions or enhancements of instrument response caused
          by the sample matrix must be corrected for by the method  of standard
          addition  (Sect.  11.5).

3.   DEFINITIONS

     3.1  DISSOLVED  - Material that will  pass through a 0.45-Aim membrane
          filter assembly, prior to  sample  acidification.

     3.2  TOTAL  RECOVERABLE - The concentration of  analyte determined on  an
          unfiltered sample following  treatment with hot dilute mineral acid.
                                      125

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3.5
3.6
 3.3  INSTRUMENT DETECTION LIMIT (IDL)  - The concentration equivalent of
      an analyte signal  equal  to three  times the standard deviation  of the
      calibration blank signal  at the selected absorbance line.

 3.4  METHOD DETECTION LIMIT (MDL)  - The minimum concentration  of an
      analyte that can be identified, measured and reported with  99%
      confidence that the analyte concentration is greater than zero.

      LINEAR DYNAMIC RANGE (LDR) -  The  concentration  range over which the
      analytical working curve  remains  linear.

      LABORATORY REAGENT BLANK  (LRB)  -  An aliquot of  reagent water that is
      treated exactly as a sample including  exposure  to  all  glassware,
      equipment, and reagents that  are  used  with samples.   The  LRB is used
      to determine if method analytes or other interferences are  present
      in the laboratory  environment,  reagents  or apparatus.

      CALIBRATION BLANK  - A volume  of ASTM type I  water  acidified  such
      that  the acid(s) concentration  is identical  to  the acid(s)
      concentration  associated  with the calibration standards.

      STOCK STANDARD SOLUTION - A concentrated  solution  containing one
      analyte prepared in the laboratory using  a assayed reference
      compound or purchased from a  reputable commercial  source.

      CALIBRATION STANDARD (CAL)  -  A  solution  prepared from  the stock
      standard solution   which  is used  to  calibrate the  instrument
      response with  respect to  analyte  concentration.

3.10  LABORATORY FORTIFIED BLANK (LFB)  - An aliquot of reagent water to
      which  a known  quantity of each  method analyte is added  in the
      laboratory.  The LFB is analyzed  exactly  like a sample, and  its
      purpose is to  determine whether the  method  is within accepted
      control  limits.

3.11  LABORATORY FORTIFIED SAMPLE MATRIX  (LFM)  - An aliquot of an
      environmental  sample  to which a known quantity of  each method
      analyte  is  added in  the laboratory.  The  LFM is analyzed exactly
      like a  sample,  and  its purpose  is to determine whether the sample
     matrix  contributes  bias to the analytical results.

3.12 QUALITY  CONTROL SAMPLE (QCS) - A solution containing a known
     concentration  of each method analyte derived from externally
     prepared test materials.   The QCS is obtained from a source external
     to the laboratory and  is  used to check laboratory performance.

3.13 MATRIX MODIFIER - A  substance added to the graphite furnace along
     with the sample in order  to minimize the interference effects by
     selective volatilization  of either analyte or matrix components.
3.7
3.8
3.9
                                126

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     3.14 STANDARD ADDITION - The addition of a known amount of analyte to the
          sample in order to determine the relative response of the detector
          to an analyte within the sample matrix.   The relative response is
          then used to assess the sample analyte concentration.

4.   INTERFERENCES

     4.1  Several interference sources may cause inaccuracies in the
          determination of trace elements by GFAA.  These interferences can be
          classified into three major subdivisions, namely spectral, non-
          spectral and memory.

          4.1.1  Spectral - Interferences resulting from the absorbance of
                 light by a molecule and/or an atom which is not the analyte
                 of interest.  Spectral interferences caused by an element
                 only occur if there is a spectral overlap between the
                 wavelength of the interfering element and the analyte of
                 interest.  Fortunately, this type of interference is
                 relatively uncommon in STPGFAA because of the narrow atomic
                 line widths  associated with STPGFAA.  In addition, the use of
                 appropriate  furnace temperature programs and  high spectral
                 purity  lamps as light  sources can minimize the possibility of
                 this type of interference.  However, molecular absorbances
                 can  span over several  hundred nanometers producing broadband
                 spectral interferences.  This type  of interference is  far
                 more common  in  STPGFAA.  The  use  of matrix modifiers,
                 selective  volatilization and  background correctors are all
                 attempts to  eliminate  unwanted non-specific absorbance.   The
                 non-specific component of  the total  absorbance can vary
                 considerably from sample type to  sample type.  Therefore,  the
                  effectiveness of a  particular background correction device
                 may  vary depending  on  the  actual  analyte wavelength used as
                 well  as the nature  and magnitude  of the  interference.

                  Spectral  interferences are also  caused  by  the emission from
                  black body radiation  produced during the atomization  furnace
                  cycle.  This black  body emission  reaches the  photomultiplier
                  tube producing  erroneous results.  The  magnitude  of this
                  interference can- be minimized by proper furnace tube
                  alignment  and  monochromator design.  In addition,  atomization
                  temperatures which  adequately volatilize the  analyte  of
                  interest  without producing unnecessary  black  body radiation
                  can  help  reduce unwanted background emission  produced during
                  atomization.

                     Note:  A spectral interference may be manifested by
                     extremely high  backgrounds (1.0 abs  ) which may exceed the
                     capability of the background corrector  and/or  it  may be
                     manifested as a non-analyte element  which  may  cause a
                     direct spectral  overlap with the analyte of interest.  If
                     a spectral  interference is suspected,  the  analyst is
                     advised to:

                                       127

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                * This background level is given as a guide and is
                not intended to serve as an absolute value which may
                be applied in all situations.

                1.  Dilute the sample if the analyte absorbance is
                large enough to sacrifice some of the sensitivity.
                This dilution may dramatically reduce a molecular
                background or reduce it to the point where the
                background correction device is capable of adequately
                removing the remaining nonspecific component.   If the
                non-specific component is produced by a spectral
                overlap with an interfering element,  the change in
                absorbance caused by dilution of the sample should
                decrease in a linear fashion, provided the undiluted
                and diluted sample are both within the linear  range
                of the interfering element.

                2.   If dilution is not acceptable  because  of the
                relatively low analyte absorbance  readings or  the
                dilution  produces  a linear decrease  in the
                nonspecific absorbance,  the  analyst  is advised  to
                investigate another analyte  wavelength which may
                eliminate  the suspected  spectral interference(s).

                3.   If dilution  and alternative  spectral lines  are
                not  acceptable,  the analyst  is advised to  attempt  to
                selectively volatilize the analyte or  the  non-
                specific component  thereby eliminating the  unwanted
                interference(s)  by  atomizing  the analyte in an
                interference-free environment.

                4.   If  none of the  above advice  is applicable and the
                spectral interference persists, an alternative
                analytical method which is not based on the same type
                of physical/chemical principle may be  necessary to
                evaluate the actual analyte concentration.

4.1.2  Non-spectral -  Interferences caused by sample components
       which inhibit the formation of free atomic analyte atoms
       during the atomization cycle.  The use of a delayed
       atomization device which provides stabilized temperatures is
       required, because these devices provide an environment  which
       is more conducive to the formation of free analyte atoms and
       thereby minimize this type of interference.  This type  of
       interference can be detected by analyzing a sample plus a
       laboratory fortified sample matrix early within any analysis
       set.   From this data,  immediately calculate the percent
       recovery (Sect. 10.4.2).   If the percent  recovery is outside
       the laboratory determined control  limits  (Sect. 10.3.3)  a
       potential problem should be suspected.  If  the result
       indicates a potential  matrix effect,  the  analyst is advised
       to:
                           128

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          1.   Perform the method of standard addition  (see  Sect.
          11.5);  if the "percent recovery" from the method of
          standard addition is drastically different from the
          percent recovery from LFM,  then lab contamination or
          another lab related problem should be suspected and
          corrected.

               NOTE: If contamination is suspected, analyze the LFB
               and calculate a percent recovery.

          2.  If the two recoveries are approximately equal*  and the
          response from the standard addition is dramatically
          different than that which would be calculated from the
          calibration curve, the sample should be suspected of a
          matrix induced interference and analyzed by the method of
          standard addition (Sect. 11.5).

               * The limitations listed in Sect. 11.5 must be met in
               order to apply these recommendations.

4.1.3  Memory interferences resulting from analyzing a sample
       containing a high concentration of an element (typically a
       high atomization temperature element) which cannot be removed
       quantitatively in one complete set of furnace steps.  The
       analyte which remains in the furnace can produce false
       positive signals on subsequent sample(s).  Therefore, the
       analyst should establish the analyte concentration which can
       be injected into the furnace and adequately removed in one
       complete set of furnace cycles.  This concentration
       represents the maximum concentration of analyte within a
       sample which will not cause a memory interference on the
       subsequent sample(s).  If this concentration is exceeded, the
       sample should be diluted and a blank should be analyzed (to
       assure the memory affect has been eliminated) before
       reanalyzing the diluted sample.

          Note:  Multiple clean out furnace cycles may be necessary
          in order to fully utilize the LDR for certain elements.

4.1.4  Specific Element Interferences

          Antimony:  Antimony suffers from an interference
          produced by KpS04  .   In the absence of hydrogen in the
          char cycle (1300°C*), K2S04  produces  a relatively  high
          (1.2 abs) background absorbance which can produce a
          false signal even with Zeeman background correction.
          However, this background level can be dramatically
          reduced (0.1 abs) by the use of a hydrogen/argon gas
          mixture in the char step.  This reduction in background
          is strongly influenced by the temperature of the char
          step.
                            129

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5.   SAFETY
                          * The actual  furnace temperature may vary from
                          instrument to instrument.   Therefore,  the actual
                          furnace temperature should be  determined on  an
                          individual  bases.

                     Aluminum:   The Pd  may have elevated levels  of Al  which
                     will  cause elevated blank absorbances.

                     Arsenic:   The HC1  present from  the  digestion  procedure  can
                     influence  the sensitivity for As.   A 1% HC1 solution with
                     Pd  used as a modifier results in a  40% loss in sensitivity
                     relative to the analyte  in a 1% HN03  solution.  The use of
                     Pd/Mg/H2 as  a modifier reduces  this  suppression to  about
                     10%.

                     Cadmium:   The HC1  present from  the  digestion  procedure  can
                     influence  the sensitivity for Cd.   A 1% HC1 solution with
                     Pd  used as a modifier results in a  70%  loss in sensitivity
                     relative to the  analyte  in a 1% HN03  solution.  The use of
                     Pd/Mg/H2 as  a modifier reduces  this  suppression to less
                     than  10%.

                     Copper:  Pd lines  at  324.27 nm  and  325.16 nm  may  produce
                     an  interference  on  the Cu line  at 324.8 nm5.

                     Lead:   The HC1  present from the digestion procedure can
                     influence  the  sensitivity for Pb.   A 1% HC1 solution with
                     Pd  used as a modifier results in a  70%  loss in sensitivity
                     relative to the  analyte  response in  a 1% HNO,  solution.
                     The use of Pd/Mg/H2 as a modifier reduces this suppression
                     to  less than  10%.

                     Selenium:   Iron  has been  shown  to suppress Se  response
                     with continuum source background correction5.   In
                     addition,  the use of  hydrogen as a  purge gas during the
                     dry and char  steps can cause a  suppression in  Se  response
                     if not  purged from the furnace  prior  to  atomization.

                     Silver:  The  Pd  used  in the modifier  preparation may have
                     elevated levels  of Ag which will cause  elevated blank
                     absorbances.
     5.1  The toxicity or carcinogenicity of reagents used in this method has
          not been fully established.  Each chemical should be regarded as a
          potential health hazard, and exposure to these compounds should be
          as low as reasonably achievable.  Each laboratory is responsible for
          maintaining a current awareness file of OSHA regulations regarding
          the safe handling of the chemicals specified in this methodf'2.  A
          reference file of material data handling sheets should also be
          available to all personnel involved in the chemical  analysis.
                                      130

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     5.2  The graphite tube during atomization emits intense UV radiation.
          Suitable precautions should be taken to protect personnel  from such
          a hazard.

     5.3  The use of argon/hydrogen gas mixture during the dry and char steps
          may evolve a considerable amount of HC1 gas.  Therefore, adequate
          ventilation is required.

6.   APPARATUS AND EQUIPMENT

     6.1  GRAPHITE FURNACE ATOMIC ABSORBANCE SPECTROPHOTOMETER

          6.1.1  The GFAA spectrometer must be capable of programmed heating
                 of the graphite tube and the associated delayed atomization
                 device.  The instrument should be equipped with an adequate
                 background correction device capable of removing undesirable
                 non-specific absorbance over the spectral region of interest.
                 The capability to record relatively fast (< 1 sec)  transient
                 signals and evaluate data on a peak area basis is preferred.
                 In addition, a recirculating refrigeration bath is
                 recommended for improved reproduc-ibility of furnace
                 temperatures.  The data shown in the tables were obtained
                 using the stabilized temperature platform and Zeeman
                 background correction.

          6.1.2  Single element hollow cathode lamps or single element
                 electrodeless discharge lamps along with the associated power
                 supplies.

          6.1.3  Argon gas supply (high-purity grade, 99.99%).

          6.1.4  A 5% hydrogen in argon gas mix and the necessary hardware to
                 use this gas mixture during specific furnace cycles.

          6.1.5  Autosampler - Although not specifically required, the use of
                 an autosampler is highly recommended.

     6.2  GRAPHITE FURNACE OPERATING CONDITIONS—A guide to experimental
          conditions for the applicable elements are shown in Table 2

     6.3  SAMPLE PROCESSING EQUIPMENT

          6.3.1  Balance - Analytical, capable of accurately weighing to
                 0.1 mg.

          6.3.2  Hot Plate - Corning PC100 or equivalent.

          6.3.3  Centrifuge - Steel cabinet with guard bowl, electric timer
                 and brake.

          6.3.4  Drying Oven capable of ± 3°C temperature control.
                                      131

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     6.4  LABWARE - The determination of trace level  elements requires a
          consideration of potential sources of contamination and analyte
          losses.  Potential contamination sources include improperly cleaned
          laboratory apparatus and general contamination within the laboratory
          environment from dust, etc.  A clean laboratory work area designated
          for trace element sample handling must be used.  Sample containers
          can introduce positive and negative errors in the determination of
          trace elements by contributing contaminants through surface
          desorption or leaching and/or depleting element concentrations
          through adsorption processes.  All reusable labware (glass, quartz,
          polyethylene, Teflon etc.), including the sample container, should
          be cleaned prior to use.  Labware should be soaked overnight and
          thoroughly washed with laboratory-grade detergent and water, rinsed
          with water, and soaked for four hours in a mixture of dilute nitric
          and hydrochloric acid (1+2+9), followed by rinsing with ASTM type I
          water and oven drying.

                 NOTE:  Chromic acid must not be used for cleaning glassware.

          6.4.1  Glassware - Volumetric flasks and graduated cylinders.

          6.4.2  Assorted calibrated pipettes.

          6.4.3  Conical Phillips beakers, 250-mL with 50-mm watch glasses.
                 Griffin beakers, 250-mL with 75-mm watch glasses.

          6.4.4  Storage bottles - Narrow mouth bottles, Teflon FEP
                 (fluorinated ethylene propylene) with Tefzel ETFE (ethylene
                 tetrafluorethylene) screw closure, 125-mL and 250-mL
                 capacities.

          6.4.5  Wash bottle - One piece stem, Teflon FEP bottle with Tefzel
                 ETFE screw closure, 125-mL capacity.

7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1  REAGENTS - Reagents may contain elemental impurities which might
          affect analytical data.  Because of the high sensitivity of GFAA,
          high-purity reagents should be used whenever possible.  All acids
          used for this method must be ultra high-purity grade.  Suitable
          acids are available from a number of manufacturers or may be
          prepared by sub-boiling distillation.

          7.1.1  Nitric acid, concentrated (sp.gr. 1.41) (CASRN 7697-37-2).

          7.1.2  Nitric acid (1+1) - Add 500 mL cone, nitric acid to 400 mL of
                 ASTM type I water and dilute to 1 L.

          7.1.3  Nitric acid (1+9) - Add 100 mL cone, to 400 mL of ASTM type I
                 water and dilute to 1 L.
                                      132

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     7.1.4  Hydrochloric acid,  concentrated (sp.gr.  1.19) (CASRN 7647-01-
            0).

     7.1.5  Hydrochloric acid (1+4) - Add 200 mL cone, hydrochloric acid
            to 400 ml  ASTM type I water and dilute  to 1000 ml.

     7.1.6  Tartaric acid. ACS reagent grade (CASRN  87-69-4).

     7.1.7  Matrix Modifier, dissolve 300 mg Palladium (Pd) powder in
            concentrated HNO, (1  ml of HN03, adding  10 mL of  concentrated
            HC1 if necessary).   Dissolve 200 mg.of Mg(N03)2 in  ASTM type
            1 water.  Pour the two solutions together and dilute to 100
            ml with ASTM type 1 water.

               Note: It is recommended that the matrix modifier be
               analyzed separately in order to assess the contribution of
               the modifier to the overall laboratory blank.

     7.1.8  Ammonium hydroxide, concentrated (sp.gr. 0.902)  (CASRN 1336-
            21-6).

7.2  WATER - For all sample preparation and dilutions, ASTM type I water
     (ASTM D1193) is required.   Suitable water may be prepared by passing
     distilled water through a mixed bed of anion and cation exchange
     resins.

7.3  STANDARD STOCK SOLUTION - May be purchased from a reputable
     commercial source or prepared from ultra high-purity grade chemicals
     or metal (99.99 - 99.999% pure).  All salts should be dried for 1 h
     at 105°C, unless otherwise  specified.  (CAUTION:  Many  metal salts
     are extremely toxic if inhaled or swallowed.  Wash hands thoroughly
     after handling).  The stock solution should be  stored in Teflon
     bottles.  The following procedures may be used  for preparing stan-
     dard stock solutions:

            NOTE:  Some metals, particularly those which form surface
            oxides, require cleaning prior to being  weighed.   This may be
            achieved by pickling the surface of the  metal in acid.  An
            amount in excess of the desired weight should be pickled
            repeatedly, rinsed with water, dried and weighed until the
            desired weight is achieved.

     7.3.1  Aluminum solution,  stock, 1 ml = 1000 /zg Al: Pickle aluminum
            metal in warm (1+1) HC1 to an exact weight of 0.100 g.
            Dissolve in 10 ml cone. HC1 and 2 ml cone, nitric acid,
            heating to effect solution.  Continue heating until volume is
            reduced to 4 ml.  Cool and add 4 ml ASTM type I water.  Heat
            until the volume is reduced to 2 ml.  Cool and dilute to
            100 mL with ASTM type I water.
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7.3.2  Antimony  solution, stock,  1 ml =  1000 ng  Sb:  Dissolve
       0.100 g antimony powder  in 2 ml (1+1) nitric  acid and 0.5 ml
       cone, hydrochloric acid, heating  to effect solution.  Cool,
       add       20 ml ASTM type I water  and 0.15g tartaric acid.
       Warm the  solution to dissolve the white precipitate.  Cool
       and dilute to 100 ml with ASTM type I water.

7.3.3  Arsenic solution, stock, 1 ml = 1000 /LUJ As: Dissolve
       0.1320 g  As203 in  a  mixture of 50  ml ASTM  type I water and 1
       ml cone,  ammonium hydroxide.  Heat gently to  dissolve.  Cool
       and acidify the solution with 2 ml cone, nitric  acid.  Dilute
       to 100 ml with ASTM type I water.
7.3.4  Beryllium solution, stock 1 ml = 500 /Ltg  Be:  Dissolve  1.965  g
       BeS04.4HpO (DO NOT DRY)  in  50  ml  ASTM Type I  water.   Add 2 ml
       cone, nitric  acid.  Dilute to 200 mL with ASTM type I water.
7.3.5  Cadmium solution, stock, 1 ml = 1000 /ig  Cd:  Pickle  Cd  metal
       in (1+9) nitric acid to an exact weight  of 0.100 g. Dissolve
       in 5 mL (1+1) nitric acid, heating to effect solution.  Cool
       and dilute to 100 ml with ASTM type I water.

7.3.6  Chromium solution, stock, 1 ml = 1000 jug Cr: Dissolve
       0.1923g Cr03 in a solution mixture of 10 ml ASTM type I water
       and 1 ml cone, nitric acid.  Dilute to 100 mL with ASTM type
       I water.

7.3.7  Cobalt solution, stock 1 mL = 1000 jug Co: Pickle Co metal  in
       (1+9) nitric acid to an exact weight of  0.100 g. Dissolve  in
       5 mL (1+1) nitric acid, heating to effect solution.  Cool  and
       dilute to 100 mL with ASTM type I water.

7.3.8  Copper solution, stock, 1 mL = 1000 ^9 Cu: Pickle Cu metal
       in (1+9) nitric acid to an exact weight  of 0.100 g. Dissolve
       in 5 mL (1+1) nitric acid, heating to effect solution.  Cool
       and dilute to 100 mL with ASTM type I water.

7.3.9  Iron solution, stock, 1 mL = 1000 ng Fe:  Pickle Fe metal  in
       (1+9) hydrochloric acid to an exact weight of 0.100 g.
       Dissolve in 10 mL (1+1) hydrochloric acid, heating to effect
       solution.   Cool and dilute to 100 mL with ASTM type I water.

7.3.10 Lead solution, stock, 1 mL = 1000 ;ug Pb:  Dissolve 0.1599 g
       PbN03 in 5 mL (1+1)  nitric acid.   Dilute  to  100 mL  with ASTM
       type I water.

7.3.11 Manganese solution,  stock, 1 mL = 1000 jug Mn: Pickle
       manganese flake in (1+9) nitric acid to an exact weight of
       0.100 g.  Dissolve in 5 mL (1+1)  nitric acid, heating to
       effect solution.  Cool  and dilute to 100 mL with ASTM type I
       water.
                            134

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    7.3.12 Nickel solution, stock,  1 ml = 1000 ng Ni:  Dissolve 0.100 g
           nickel powder  in 5 ml cone, nitric acid, heating to  effect
           solution.  Cool and dilute to 100 ml with ASTM type  I water.

    7.3.13 Selenium  solution, stock, 1 ml = 1000  /zg Se:  Dissolve
           0.1405 g  Se02  in 20 ml ASTM type I water.  Dilute to 100 ml
           with ASTM type I water.

    7.3.14 Silver solution, stock,  1 ml = 1000 /Ltg Ag:  Dissolve 0.100 g
           silver metal  in 5 ml  (1+1) nitric acid, heating to  effect
           solution.  Cool and dilute to 100 ml with ASTM type I water.
           Store  in  amber container.

    7.3.15 Thallium  solution, stock 1 ml =  500 jug Tl:  Dissolve 0.1303 g
           T1NO, in  a solution mixture of 10 ml ASTM type I water and  2
           ml cone,  nitric acid.   Dilute to 200 ml with  ASTM type  I
           water.

    7.3.16 Tin solution,  stock,  1  ml =  1000 ^g Sn:  Dissolve 0.100 g Sn
           shot in  20 ml (1+1)  hydrochloric acid, heating  to effect
           solution. Cool and  dilute  to  100 ml with  (1+1)  hydrochloric
           acid.

     7.3.17 Zinc solution, stock,  1 ml  = 1000 /zg Zn:  Pickle zinc metal
            in (1+9)  nitric acid to an  exact weight of 0.100  g.  Dissolve
            in 5 ml  (1+1) nitric acid,  heating  to  effect  solution.   Cool
            and dilute to 100  ml with ASTM  type I  water.

7.4  PREPARATION OF  CALIBRATION  STANDARDS  -  Fresh  calibration standards
     (CAL Solution)  should be  prepared  every two weeks or as  needed.
     Dilute  each of the  stock standard  solutions to levels  appropriate to
     the operating range of the  instrument  using the appropriate acid
     diluent   (see note).  The element concentrations in each  CAL solution
     should  be sufficiently high to produce good measurement precision
     and to  accurately define the slope of the  response curve.   The
     instrument calibration should be initially verified using  a quality
     control   sample  (Sect. 7.6).

            NOTE: The appropriate acid diluent for dissolved elements in
            water samples  is 1% HN03.  For  total  recoverable  elements in
            waters the appropriate acid diluent is 2% HN03  and  1% HC1.
            Finally, the  appropriate acid diluent for total recoverable
            elements in solid samples is 2% HN03 and  2% HC1.  The reason
            for these different diluents is to match the types of acids
            and the  acid  concentrations of the samples with the acid
            present  in the standards and blanks.

7.5  BLANKS - Two types of blanks are required for this method.  A
     calibration blank is  used to establish the analytical  calibration
     curve and the laboratory reagent blank (LRB)  is used to assess
     possible contamination from the sample preparation procedure and to


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     7.5.2
7.6
7.7
           assess  spectral  background.  All diluent  acids  should be made  from
           concentrated  acids  (Sects. 7.1.1, 7.1.4)  and ASTM type  I water.

           7.5.1   Calibration  blank - Consists of the appropriate  acid diluent
                  (Sect.  7.4 note) (HC1/HN03) in ASTM type I water.

                  Laboratory reagent blank  (preparation blank) must contain all
                  the reagents  in the same  volumes as used in processing  the
                  samples.  The preparation blank must be carried  through the
                  entire  sample digestion and preparation scheme.

           QUALITY CONTROL  SAMPLE - Quality control  samples are available from
           various sources.  Dilute (with the appropriate acid (HC1/HNO,)  blank
           solution) an appropriate aliquot of analyte such that the resulting
           solution will  result in an absorbance of  approximately  0.1.

           LABORATORY FORTIFIED BLANK - To an aliquot of laboratory reagent
           blank, add an  aliquot of the stock standard to provide  a final
           concentration which will produce an absorbance of approximately 0.1
           for the analyte.  The fortified blank must be carried through the
           entire sample digestion and preparation scheme.

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1   Prior to sample collection,  consideration should be given to the
          type of data required so that appropriate preservation and
          pretreatment steps can be taken.   Filtration,  acid preservation etc.
          should be performed at the time of sample collection or as soon
          thereafter as practically possible.

     8.2  For the determination of dissolved elements,  the sample should  be
          filtered through a 0.45-jum membrane filter.  Use a portion of the
          sample to rinse the filter assembly,  discard  and then  collect the
          required volume of filtrate.   Acidify the filtrate  with (1+1)
          nitric acid immediately following filtration  to a pH of less than
          two.

     8.3  For the determination of total  recoverable elements  in aqueous
          samples, acidify with (1+1)  nitric  acid  at the  time  of collection to
          a pH of less  than two.   The  sample  should not be filtered prior to
          analysis.

                 NOTE:  Samples that  cannot  be acid  preserved at  the time  of
                 collection because  of  sampling  limitations  or transport
                 restrictions,  should be  acidified  with nitric acid to pH <2
                 upon receipt  in  the laboratory  (normally,  3 mL  of (1+1)
                 nitric  acid  per  liter  of sample is  sufficient for most
                 ambient  and  drinking water samples).  Following
                 acidification, the  sample  should be held  for  a minimum of
                 16  h before withdrawing  an aliquot  for sample processing.
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     8.4  Solid samples usually require no preservation prior to analysis
          other than storage at 4°C.

9.   CALIBRATION AND STANDARDIZATION

     9.1  CALIBRATION - Demonstration and documentation of acceptable initial
          calibration is required before any samples are analyzed arid is
          required periodically throughout sample analysis as dictated by
          results of continuing calibration checks.  After initial calibration
          is successful, a calibration check is required at the beginning and
          end of each period during which analyses are performed.

          9.1.1  Initiate proper operating configuration of instrument and
                 data system.  Allow a period of not less than 30 min for the
                 instrument to warm up if an EDL is to be used.

          9.1.2  Instrument stability must be demonstrated by analyzing a
                 standard solution of a concentration 20 times the IDL a
                 minimum of five times with the resulting relative standard
                 deviation of absorbance signals less than 5%.

          9.1.3  Initial calibration.  The instrument must be calibrated for
                 the analyte to be determined using the calibration blank
                 (Sect. 7.5.1) and calibration standards prepared at three or
                 more concentration levels within  the linear dynamic range of
                 the analyte.

     9.2  INSTRUMENT PERFORMANCE - Check the performance of the  instrument and
          verify the calibration using data gathered from analyses of
          calibration blanks, calibration standards and the quality control
          sample.

          9.2.1  After  the  calibration has been established,  it  must be
                 initially  verified  for the analyte by  analyzing the QCS
                  (Sect. 7.6).   If measurements exceed  ± 10%  of the
                 established QCS value, the analysis should  be  terminated, the
                 source of  the  problem  identified  and  corrected,  the
                  instrument recalibrated, and  the  new  calibration must  be
                 verified before continuing analyses.

          9.2.2  To verify  that  the  instrument is  properly calibrated on  a
                 continuing basis,  analyze the calibration blank and  an
                  intermediate  concentration calibration standard as  surrogate
                  samples  after every ten  analyses. The results of the
                  analyses of the  standard will  indicate whether the
                  calibration remains valid.   If  the indicated concentration  of
                  any analyte deviates from the true concentration by more than
                  10%,  the  instrument must be  recalibrated  and the response of
                  the QCS  checked as in Sect.  9.2.1. After  the QCS sample has
                  met specifications,  the  previous  ten  samples must be
                  reanalyzed in groups of five with an  intermediate


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                 concentration calibration standard analyzed after every fifth
                 sample.  If the intermediate concentration calibration
                 standard is found to deviate by more than 10%, the analyst is
                 instructed to identify the source of instrumental drift.

                    NOTE:  If the sample matrix is responsible for the
                    calibration drift and/or the sample matrix is affecting
                    analyte response, it may be necessary to perform standard
                    additions in order to assess an analyte concentration
                    (Sect. 11.5).

10.   QUALITY CONTROL (PC)

     10.1 FORMAL QUALITY CONTROL-  The minimum requirements of this QC program
          consist of an initial  demonstration of laboratory capability  and
          the analysis of laboratory reagent blanks and fortified blanks and
          samples as a continuing check on performance.   The laboratory is
          required  to maintain  performance records that define  the quality  of
          the data  thus generated.

     10.2 INITIAL DEMONSTRATION  OF  PERFORMANCE

          10.2.1  The initial  demonstration of performance is  used  to
                 characterize instrument  performance  (MDLs  and  linear  calibra-
                 tion  ranges) for analyses conducted  by  this  method.

          10.2.2  Method detection limits  (MDL) - The method detection  limit
                 should be established  for the analyte,  using reagent  water
                 (blank)  fortified at a concentration of two  to five times the
                 estimated detection  limit5.  To determine MDL values,  take
                 seven  replicate  aliquots  of the fortified reagent water and
                 process  through the entire analytical method.  Perform all
                 calculations defined in the method and  report the
                 concentration values in the appropriate  units.  Calculate the
                 MDL as follows:

                     MDL = (t)  x (S)

                where, t = Student's t value for a 99% confidence level and a
                           standard deviation estimate with n-1 degrees of
                           freedom [t = 3.14 for seven replicates],

                       S = standard deviation of the replicate analyses.

                Method detection limits should be determined every six months
                or  whenever a significant change in background  or instrument
                response is expected.

         10.2.3 Linear calibration  ranges - Linear calibration  ranges  are
                metal  dependent.  The upper limit  of the linear calibration
                range should  be  established by determining  the  signal
                responses from  a  minimum  of four different  concentration

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            standards,  one of which  is  close  to  the  upper limit  of the
            linear range.   The linear calibration  range which  may be  used
            for the analysis of samples should be  judged by the  analyst
            from the resulting data.  Linear  calibration ranges  should  be
            determined  every six months or whenever  a significant change
            in instrument  response maybe expected.

10.3 ASSESSING LABORATORY  PERFORMANCE - REAGENT  AND  FORTIFIED  BLANKS

     10.3.1 Laboratory  reagent blank (LRB) -  The laboratory must analyze
            at least one LRB (Sect.  7.5.2) with  each set of samples.
            Reagent blank data are used to assess  contamination  from  the
            laboratory  environment and  to characterize spectral
            background  from the reagents used in sample processing.  If
            an analyte  value in the  reagent blank exceeds its  determined
            MDL, then laboratory or  reagent contamination should be
            suspected.   Any determined  source of contamination should be
            corrected and the samples reanalyzed.

     10.3.2 Laboratory  fortified blank  (LFB)  - The laboratory  must
            analyze at  least one LFB (Sect. 7.7) with each set of
            samples.  Calculate accuracy as percent  recovery (Sect.
            10.4.2).  If the recovery of any analyte falls outside the
            control limits (Sect. 10.3.3), that  analyte is judged out of
            control, and the source  of the problem should be identified
            and resolved before continuing analyses.

     10.3.3 Until sufficient data (usually a minimum of 20 to  30
            analyses) become available, a laboratory should assess
            laboratory performance against recovery limits of 80-120%.
            When sufficient internal performance data become available,
            develop control limits from the percent  mean recovery  (x) and
            the standard deviation (S)  of the mean recovery.  These data
            are used to establish upper and lower control limits as
            follows:

                  UPPER CONTROL LIMIT = x + 3S
                  LOWER CONTROL LIMIT = x - 3S

            After each 5-10 new recovery measurements, new control limits
            should be calculated using only the most recent 20 to 30 data
            points.

            NOTE:  Antimony and Aluminum do manifest relatively low
            percent recoveries  (see Table 1A, NBS River Sediment 1645).

10.4 ASSESSING  ANALYTE RECOVERY - LABORATORY FORTIFIED SAMPLE MATRIX

     10.4.1 The laboratory must fortify a minimum of 10% of the samples
            or  one fortified  sample per set, whichever is greater.
            Ideally for solid  samples,  the concentration added should be
            approximately equal to 0.1 abs units after the solution has

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                  been diluted.   In other words  if the  sample (after dilution)
                  results in an  absorbance of 0.05,  ideally the  laboratory
                  fortified sample will  result in  an absorbance  of 0.150  (after
                  dilution).  Over time,  samples from all  routine  sample
                  sources should be fortified.

           10.4.2  Calculate the  percent  recovery for the  analyte,  corrected  for
                  background concentrations measured in the unfortified sample,
                  and  compare these values to the  control  limits established in
                  Sect.  10.3.3 for the analyses  of LFBs.   Fortified recovery
                  calculations are not required  if the fortified concentration
                  is less than 10% of the sample background concentration.
                  Percent recovery may be calculated in units  appropriate to
                  the  matrix,  using the  following  equation:

                  R =  (Cs - C) x 100
                          S
                  where,

                  R  = percent recovery.
                  Cs = fortified sample concentration.
                  C  = sample  background  concentration.
                  S  = concentration equivalent  of the fortified sample.

          10.4.3  If the  recovery  of the  analyte on  the fortified sample falls
                  outside  the designated  range,  and  the laboratory  performance
                  on the  LFB for the analyte  is  shown to be  in control
                  (Sect.  10.3) the  recovery problem  encountered with the
                  fortified  sample  is judged to  be matrix related (Sect. 4),
                  not system related.  The data obtained for that analyte
                  should be verified with the methods of standard additions
                  (Sect. 11.5).

     10.5 QUALITY CONTROL SAMPLES  (QCS)  - Each quarter,  the laboratory should
          analyze one or more QCS  (if available).    If criteria provided with
          the QCS are not met, corrective action should be taken and
          documented.

11.   PROCEDURE

     11.1 SAMPLE PREPARATION - DISSOLVED ELEMENTS

          11.1.1 For the determination  of dissolved elements in  drinking
                 water,  wastewater, ground and surface  waters, take a 100-mL
                 (± ImL) aliquot of the filtered acid preserved  sample, and
                 add 1 mL of concentrated nitric acid.  The sample is now
                 ready for analysis. Allowance  should  be made in  the
                 calculations for the appropriate  dilution factors.
                                     140

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               NOTE:  If a precipitate is  formed during.acidification,
            .''  transport or storage,  the  sample aliquot  must be treated
               using  the procedure In-Sect.-, 11.2.1 prior to analysis.

11.2 SAMPLE PREPARATION - TOTAL RECOVERABLE ELEMENTS.

     11.2.1 For the determination of total  recoverable elements in water
         .   or waste water, take a 100-mL (± 1 mL) aliquot from a well
            mixed, acid preserved sample and transfer it to a 250-mL
            Griffin beaker.  Add 1 mL of concentrated HNO, and 0.5 mL  of
            concentrated HC1.  Heat the sample on a hot plate at 85°C
            until the volume has been reduced to approximately 20 mL,
            ensuring that the sample does not boil.   (A spare beaker
            containing 20 mL of water can be used as  a gauge.)

               NOTE: For proper heating adjust the temperature control of
               the hot plate such that an uncovered beaker containing
               50 mL of water located in the center of the hot plate can
               be maintained at approximately but no  higher than 85°C.
               Evaporation  time for  100 mL of sample  at 85°C  is
               approximately 2 h with the rate of evaporation rapidly
               increasing  as the sample volume approaches  20 mL.

            Cover the  beaker with a  watch glass  and reflux for 30 min.
            Slight boiling  may occur but vigorous boiling- should  be
            avoided.   Allow to cool and quantitatively transfer  to
            either a 50-mL  volumetric or a 50-mL class A  stoppered
            graduated  cylinder.  Dilute to volume with ASTM type  I water
            and  mix.   Centrifuge the sample  or allow  to stand  overnight
            to separate  insoluble material.  The sample is  now ready  for
            analysis.   Prior to  the  analysis of  samples the calibration
            standards  must be  analyzed and the  calibration verified using
            a  QC sample  (Sect.  9).   Once the calibration  has  been
            verified,  the instrument is  ready  for sample  analysis.
            Because  the effects  of  various matrices  on  the stability  of
            diluted  samples cannot  be  characterized,  samples  should be
            analyzed as soon as  possible after preparation.

      11.2.2 For  the  determination of total  recoverable  elements in solid
            samples  (sludge,  soils,  and  sediments),  mix the sample
            thoroughly to achieve homogeneity  and weigh accurately a  1.0
             ± 0.01 g portion of the sample.   Transfer to a 250-mL
             Phillips beaker. Add 4 mL (1+1)  nitric acid and 10 mL (1+4)
             HC1.  Cover with a watch glass.   Heat the sample on a hot
             plate and gently reflux for 30 min.   Very slight boiling  may
             occur, however, vigorous boiling must be avoided to prevent
             the loss of the HC1  azeotrope.
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                NOTE:  For proper heating adjust the temperature control
                of the hot plate such that an uncovered Griffin beaker
                containing 50 ml of water located in the center of the hot
                plate can be maintained at a temperature approximately but
                no higher than 85°C.

             Allow the sample to cool and quantitatively transfer to
             either 100-mL (± 1 mL) volumetric flask or a 100-mL class A
             stoppered graduate cylinder.  Dilute to volume with ASTM type
             I water and mix.  Centrifuge the sample or allow to stand
             overnight to separate insoluble material.   The sample is now
             ready for analysis.   Prior to the analysis of samples the
             calibration standards must be analyzed  and the calibration
             verified using a QC  sample (Sect.  9).   Once the calibration
             has been verified,  the instrument is ready for sample
             analysis.   Because the effects  of various  matrices  on the
             stability of diluted samples cannot  be  characterized,  samples
             should  be analyzed  as  soon  as possible  after preparation.

                NOTE:  Determine the  percent  solids in the sample for  use
                in calculations and  for  reporting data  on a  dry  weight
                Dasis.

      11.2.3  Appropriate  digestion procedures  for biological  tissues
             should be utilized prior to  sample analysis.

11.3  For every  new or unusual matrix, it  is highly recommended  that  an
      inductively  coupled plasma  atomic emission  spectrometer be used to
      screen  for high element concentrations.  Information gained from
      this may be  used to prevent potential damage of the instrument  and
      better  estimate which elements may require  analysis by qraohite
      furnace.                                                  v

11.4  Samples having concentrations higher than the established linear
     dynamic range should be diluted into range and  reanalyzed   If
     methods of standard additions are required,  follow the instructions
      i n oscL* 11«o.

11.5 STANDARD ADDITIONS - If methods of standard  addition are required
     the following procedure is recommended.

     11.5.1 The standard addition technique4  involves preparing  new
            standards in the sample matrix by adding known amounts of
            standard to  one or more  aliquots  of the  processed sample
            solution.   This technique compensates for a sample
            constituent  that  enhances or depresses the  analyte siqnal
            thus producing  a  different  slope  from that'of the calibration
            standards.   It  will not  correct  for additive interference
            which  causes  a  baseline  shift.  The simplest version of this
            technique  is  the  single-addition method.  The procedure is
            as  follows.   Two  identical aliquots of the  sample solution
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                each of volume Vx,  are taken.   To the first (labeled A)  is
                added a small volume Vs of a standard analyte solution of
                concentration cs.   To the second (labeled B)  is added the
                same volume V  of the solvent.   The analytical  signals of A
                and B are measured and corrected for nonanalyte signals.  The
                unknown sample concentration cx is calculated:
                                     SBV3CS

                                    (SA-SB) Vx
                where SA and SB are the analytical  signals (corrected for the
                blank) of solutions A  and B, respectively.  Vs and cs should
                be chosen so that  S. is roughly twice SB on the average.  It
                is best  if Vs is made much less than Vx, and thus cs  is  much
                greater  than c  , to avoid excess dilution of the sample
                matrix.   If a  separation or  concentration step  is  used,  the
                additions are  best made first  and  carried through  the entire
                procedure.  For the results  front this technique  to be valid,
                the  following  limitations must be  taken into  consideration:

                1. The  analytical  curve must be linear.

                2. The  chemical form  of the  analyte added must respond  the
                   same  as  the analyte in the  sample.

                3. The  interference effect must be constant over the working
                   range of concern.

                4. The  signal  must be corrected for any additive
                    interference.

12.   CALCULATIONS

     12.1 Do not report  element concentrations  below the determined MDL.

     12.2 For aqueous samples prepared by total recoverable procedure (Sect.
          11.2.1), multiply solution concentrations by the appropriate
          dilution factor.  Round the data to the tenths place and report the
          data in M9/L with up  to  three significant figures.

     12.3 For solid samples prepared by total recoverable procedure  (Sect.
          11.2.2)  round the solution concentration  (M9/L  in the  analysis
          solution) to the tenths  place and multiply by the dilution factor.
          Data should be reported  to a tenth mg/kg  up to  three significant
          figures taking into account the percent  solids  if the data are
          reported on a dry weight* basis.
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               * The dry weight should be determined on a separate sample
               aliquot  if the sample is available.  The dry weight can be
               determined by transferring a uniform 1-g aliquot to an

                        n9 d1Sh and drin  the S      t0 a constant wei'9ht
      12.4 If additional dilutions were performed, the appropriate dilution
           factor must be applied to sample values.
      12'5 Ihf Ldata 0^?jned du!:in9 the ^alyses provide an indication of
           the quality of the sample data and should be provided with the
           sample results.

 13.   PRECISION AND ACCURACY
13 '* ?,™L0^taHn^d Tru? S]?gle ! ab°ratory testing of the method are
     summarized in Table 1A-C for three solid samples consisting of SRM
     1645 River Sediment,  EPA Hazardous Soil  and EPA Electroplating
     c  !gei'i  o amplrs were PrePared "sing the procedure described  in
     aSf««   **?:  For,?ach matrix, five replicates were analyzed  and  an
     ann^9? °f-the re.Pllcates used  for determining  the  sample  background
     concentration.  Two further  pairs  of duplicates were fSrtifiec I at
     different concentration levels. The sample background
     concentration, mean spike percent  recovery,  the standard deviation
     of the average percent recovery and the  relative percent difference
     between the  duplicate  fortified determinations  are  listed  in Table
            ^h dd,1*1on> Table 1D-p  contains  a  single laboratory testing
            ?   ?  in  ac>ue?us  media  including drinking water, pond water
              V?  Sri    3mp  6S  uere PrePared "sing the  procedure described
            .  11.2.1.   For  each aqueous  matrix,  five  replicates were
            h  aC   3n avera9e of the  ^eplicates  used  for determining the
     sample  background  concentration.  Four samples were  fortified at the
     levels  reported in Table  1D-1F.  A  percent relative  standard
     deviation  is  reported  in  Table  1D-1F for the fortified samples   An
     average percent recovery  is also reported  in Tables  1D-F
           n
          in
14.   REFERENCES
     1.
     2.
    3.
    "OSHA Safety and Health Standards, General  Industry," (29CFR 1910)

    S3£°1976       and HeaUh Administration>  OSHA 2206,  revised


    "Proposed OSHA Safety and Health Standards,  Laboratories "

    SSlyP24]°1986Safety aPd HeaUh Administrat1on>  Federal  Register,

    Code of Federal  Regulations  40,  Ch.  1,  Pt.  136, Appendix B.
                                     144

-------
4.   Winefordner, J.D., "Trace Analysis:  Spectroscopic Methods for
     Elements," Chemical Analysis. Vol. 46, pp. 41-42.

5.   Waltz, B., G. Schlemmar and J. R. Mudakavi, JAAS, 1988, 3, 695.
                                  145


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     TABLE 2.   RECOMMENDED GRAPHITE FURNACE OPERATING CONDITIONS
                  AND RECOMMENDED MATRIX MODIFIER (i'3)
Element
Ag
A17
As'
Be
Cd
Co
Cr
Cu
Fe
Mn
r\t
Pb
Sb7
c* (
Se'
Sn7
Tl
Zn
Wave-
length
328.1
309.3
193.7
234.9
228.8
242.5
357.9
324.8
248.3
279.5
232.0
283.3
217.6
196.0
286.3
276.8
213.9
Slit
0.7
0.7
0.7
0.7
0.7
0.2
0.7
0.7
0.2
0.2
0.2
0.7
0.7
2.0
0.7
0.7
0.7
Temperature
Char
1000
1700
1300
1200
800
1400
1650
1300
1400
1400
1400
1250
1100
1000
14008
1000
700
(C)5
Atom.
1800
2600
2200
2500
1600
2500
26006
26006
2400
2200
2500
2000
2000
2000
2300
1600
1800
MDL4
(M9/L)
0.59
«
7.89
0.5
0.02
0.05
0.7
0.1
0.7

0.3
0.6
0.7
0.8
0.6
1.7
0.7
0.3
 1)   Matrix Modifier = 0.015 mg Pd + 0.01 mg Mg(N03)2.


 2)   A 5% H,  in Ar gas  mix  is  used  during the  dry  and  char  steps  at  300  mL/min
     tor a 11  elements.


 3)   A cool  down  step between  the char and atomization is recommended.


 4)   Obtained using  a 20  juL sample size and stop flow atomization.


 5)   Actual  char  and atomization  temperatures  may  vary from instrument to
     instrument and  are best determined on an  individual  basis.   The actual
     drying temperature may vary  depending on  the  temperature  of  the water  used
     to  cool  the  furnace.


 6)   A 7  second atomization is  necessary to  quantitatively  remove the analyte
     from the graphite  furnace.


 7)  An electrode!ess discharge lamp was  used  for  this  element.


8)  An additional low  temperature  (approximately  200°C)  prechar  is
    recommended.


9)  Pd modifier was determined to have trace  level contamination  of  this
    element.
                                      152

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                          Method 200.10

DETERMINATION OF TRACE ELEMENTS IN MARINE WATERS BY ON-LINE CHELATION
 PRECONCENTRATION AND INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY
                          Stephen E.  Long
                   Technology Applications,  Inc.

                                and

                        Theodore D. Martin
                     Inorganic Chemistry  Branch
                    Chemistry Research Division
                            Revision  1.4
                             April  1991
            ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
                 OFFICE OF RESEARCH AND DEVELOPMENT
                U.S. ENVIRONMENTAL PROTECTION AGENCY
                       CINCINNATI, OHIO 45268
                                 153

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                                   METHOD  200.10

      DS5H5NATIOM OF TRACE ELEMENTS IN MARINE WATERS BY ON-LINE CHELATION
       PRECONCENTRATION AND INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY


 1.   SCOPE AND APPLICATION

      1.1  This method describes procedures for preconcentration and
           determination of total  recoverable trace elements in marine waters
           including estuanne water, seawater and brines.

      1.2  Acid sol utilization is  required prior to the determination of total
           recoverable elements to facilitate breakdown of complexes or
           colloids which might influence trace element recoveries.  This
           method should only be used for preconcentration and determination of
           trace elements in aqueous samples.

      1.3  This method is applicable to the following elements:
      1.4
     1.5
     Element              Chemical  Abstract Services
                          Registry Numbers (CASRN)

     Cadmium    (Cd)               7440-43-9
     Cobalt     (Co)               7440-48-4
     Copper     (Cu)               7440-50-8
     Lead       (Pb)               7439-92-1
  •   Nickel      (Ni)               7440-02-0
     Uranium    (U)                7440-61-1
     Vanadium   (V)                7440-62-2

 Method  detection  limits  (MDLs)  for these  elements will  be  dependent
 on  the  specific instrumentation  employed  and  the  selected  operating
 conditions.   However,  the MDLs  should  be  essentially  independent of
 the matrix  because elimination  of  the  matrix  is a feature  of the
 method.  MDLs  in  reagent water,  which  were determined usinq the
 procedure described  in Sect.  10.2.2, are  listed in Table 1.

 A minimum of six  months experience  in  the  use of  commercial
 )?rDrMcfn*ation for  induct1vely  coupled plasma mass spectrometry
 rro  MC I ls  recommended.  Specific  information regarding the use of
 Meth d 200 8^ determinat1on of  trace  elements may be found in USEPA
2.   SUMMARY OF METHOD
     2.1
This method is used to preconcentrate trace elements using an
inn nodi acetate functionalized chelating resin(2'3).   Following acid
solubilization, the sample is buffered prior to chelating column

                            154

-------
          entry using an on-line system.   Group I and II metals,  as well  as
          most anions, are selectively separated from the analytes by elution
          with ammonium acetate at pH 5.5.  The analytes are subsequently
          eluted into a simplified matrix consisting of dilute nitric acid and
          are determined by ICP-MS using a directly coupled on-line
          configuration.

3.   DEFINITIONS

     3.1  TOTAL RECOVERABLE - The concentration of analyte determined on an
          unfiltered sample following treatment with hot dilute mineral acid.

     3.2  METHOD DETECTION LIMIT  (MDL)' - The minimum concentration of an
          analyte that can be identified, measured and reported with 99%
          confidence that the analyte concentration is greater than zero.

     3.3  LINEAR DYNAMIC RANGE  (LDR) - The concentration range over which the
          analytical working curve remains linear.

     3.4  LABORATORY REAGENT BLANK (LRB)  (preparation blank) - An  aliquot of
          reagent water that is treated  exactly  as a sample including exposure
          to  all labware, equipment, solvents, reagents, and internal
          standards  that  are used with other samples.  The  LRB is  used to
          determine  if method analytes or other  interferences are  present  in
          the laboratory  environment, reagents or  apparatus.

     3.5  CALIBRATION  BLANK - A volume of ASTM type  I water acidified with the
          same acid  matrix as  is  present in the  calibration standards.

     3  6  INTERNAL  STANDARD -  Pure analyte(s)  added  to  a solution  in  known
          amount(s)  and used to measure  the relative responses of  other  method
          analytes  that are components of the  same solution.  The  internal
          standard  must be an  analyte that  is  not  a  sample  component.

     3.7  STOCK STANDARD SOLUTION -  A concentrated solution containing  one or
          more analytes prepared  in  the  laboratory using assayed reference
          compounds or purchased  from a  reputable  commercial  source.

     3.8  CALIBRATION STANDARD (CAL) -  A solution  prepared  from  the stock
           standard  solution(s)  which is  used  to calibrate  the instrument
           response  with respect to analyte  concentration.

      3.9   TUNING SOLUTION -  A solution  which  is used to determine acceptable
           instrument performance prior  to calibration  and  sample analyses.

      3.10 LABORATORY FORTIFIED BLANK (LFB)  -  An aliquot of reagent water to
           which known quantities of the method analytes are added in the
           laboratory.  The LFB is analyzed exactly like a sample, and its
           purpose is to determine whether the method is within accepted
           control limits.
                                       155

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      3.11 LABORATORY FORTIFIED SAMPLE MATRIX (LFM) - An aliquot of an
           environmental sample to which known quantities of the method
           analytes are added in the laboratory.  The LFM is analyzed
           exactly!ike a sample, and its purpose is to determine whether the
           sample matrix contributes bias to the analytical  results   The
           background concentrations of the analytes in the  sample matrix must
           be determined in a separate aliquot and the measured values in the
           LFM corrected for the concentrations found.

      3.12 QUALITY CONTROL SAMPLE (QCS) - A solution containing known
           concentrations of method analytes which is used to  fortify an
           aliquot of LRB matrix.   The QCS is obtained from  a  source external
           to the laboratory and is used to check laboratory performance.

      INTERFERENCES
      4.1
     4.2
     4.3
      A discussion of interferences relating to the use of ICP-MS may be
      found in USEPA Method 200.8<1).  A principal  advantage of this
      method is the selective elimination of species giving rise to
      polyatomic spectral  interferences on certain transition  metals  (e.g
      removal  of the chloride interference on vanadium).   As the majority
      of the sample matrix is removed,  matrix induced physical
      interferences are also substantially reduced.

      Low recoveries may be encountered in the preconcentration  cycle if
      the trace elements are complexed  by competing  chelators  in the
      sample or are present as  colloidal  material.   Acid  solubilization
      pretreatment is employed  to  improve analyte  recovery and to minimize
      adsorption,  hydrolysis and precipitation effects.

      Memory interferences  from the  chelating  system may  be  encountered
      especially  after analyzing a sample containing high  concentrations
      of  the analytes.   A thorough column rinsing  sequence  following
      elution  of  the analytes is necessary  to  minimize  such  interferences.
5.   SAFETY
     5.1
     Each chemical reagent used in this method should be regarded as a
     potential health hazard and exposure to these reagents should be as
     low as reasonably achievable.  Each laboratory is responsible for
     maintaining a current awareness file of OSHA regulations regarding
     the safe handling of the chemicals specified in this method^'   A
     reference file of material data handling sheets should also be
     available to all personnel involved in the chemical  analysis.

5.2  Analytical  plasma sources emit radiofrequency radiation in addition
     to intense UV radiation.  Suitable precautions should be taken to
     protect personnel from such hazards.
                                     156

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6. APPARATUS AND EQUIPMENT

    6.1 PRECONCENTRATION SYSTEM - System containing no metal parts in the
        analyte flow path, configured as shown in Figure 1.

        6.1.1  Column - Macroporous iminodiacetate chelating resin (Dionex
               Metpac CC-1 or equivalent).

        6.1.2  Sample loop - 10 ml_ loop constructed from narrow bore, high-
               pressure inert tubing, Tefzel ETFE (ethylene tetra-
               fluoroethylene) or equivalent.

        6.1.3  Eluent pumping system (PI) - Programmable flow, high pressure
               pumping system,.capable of delivering either one of two
               eluents at a pressure up to 2000 psi and a flow rate of 1-5
               mL/min.

        6.1.4  Auxiliary pumps - On line buffer pump (P2), piston pump
               (Dionex QIC pump or equivalent) for delivering 2M ammonium
               acetate buffer solution; carrier pump (P3). peristaltic pump
               (Gilson Minipuls or equivalent) for delivering 1% nitric acid
               carrier solution; sample pump (P4). peristaltic pump for
               loading sample loop.

        6.1.5  Control valves - Inert double stack, pneumatically operated
               four-way slider valves with connectors.

               6.1.5.1 Argon gas supply regulated at 80-100 psi.

        6.1.6  Solution reservoirs - Inert containers, e.g. high density
               polyethylene (HOPE) for holding eluent and carrier reagents.

        6.1.7  Tubing - High pressure, narrow bore, inert tubing (e.g.
               Tefzel ETFE or equivalent) for interconnection of pumps/valve
               assemblies and a minimum length for connection of the
               preconcentration system to the ICP-MS instrument.

   6.2  INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETER

        6.2.1  Instrument capable of scanning the mass range 5-250 amu with
               a minimum resolution capability of 1 amu peak width at 5%
               peak height.  Instrument may be fitted with a conventional or
               extended dynamic range detection system.

        6.2.2  Argon gas supply (high-purity grade, 99.99%).

        6.2.3  A mass-flow controller on the nebulizer gas supply is
               recommended.  A water-cooled spray chamber may be of benefit
               in reducing some types of interferences  (e.g., polyatomic
               oxide species).
                                    157

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6.3
      6.2.4  Operating conditions - Because of the diversity of instrument
            hardware, no detailed instrument operating conditions are
            provided.  The analyst is advised to follow the recommended
            operating conditions provided by the manufacturer.

      LABWARE - For the determination of trace elements, contamination and
      loss are of critical consideration.  Potential contamination sources
      include improperly cleaned laboratory apparatus and general
      contamination within the laboratory environment.  A clean laboratory
      work area, designated for trace element sample handling must be
      used.  Sample containers can introduce positive and negative errors
      in the determination of trace elements by (1) contributing
      contaminants through surface desorption or leaching, (2) depleting
      element concentrations through adsorption processes.  For these
      reasons, borosilicate glass is not recommended for use with this
      method.  All labware in contact with the sample should be cleaned
      prior to use.  Labware may be soaked overnight and thoroughly washed
      with laboratory-grade detergent and water, rinsed with water, and
      soaked for 4 h in a mixture of dilute nitric and hydrochloric acids,
      followed by rinsing with ASTM type I water and oven drying.

      6.3.1  Griffin beakers,  250 ml,  polytetrafluoroethylene (PTFE) or
            quartz.

      6.3.2  Storage bottles - Narrow mouth bottles, Teflon FEP
            (fluorinated ethylene propylene),  or HOPE,  125 mL and 250 ml
            capacities.

6.4  SAMPLE PROCESSING EQUIPMENT

     6.4.1  Air displacement  pipetter - Digital  pipet system capable of
            delivering volumes from 10 to 2500 #L with  an assortment of
            metal-free,  disposable pipet tips.

     6.4.2  Balances - Analytical  balance,  capable of accurately  weighing
            to ± 0.1 mg;  top  pan balance,  accurate to ± O.Olg.

     6.4.3  Hot plate -  Corning  PC100 or equivalent.

     6.4.4  Centrifuge -  Steel cabinet with  guard bowl,  electric  timer
            and brake.

     6.4.5  Drying oven -  Gravity  convection oven with  thermostatic
            control  capable of maintaining  105°C ± 5°C.

     6.4.6  pH meter -  Bench  mounted  or hand-held electrode  system with  a
            resolution of  ± 0.1  pH units.
                                158

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7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1  WATER - For all sample preparation and dilutions, ASTM type I water
          (ASTM QM'93) is required.

     7.2  Reagents may contain elemental impurities which might affect the
          integrity of analytical data.  Owing to the high sensitivity of this
          method, ultra high-purity reagents must be used unless otherwise
          specified.  To minimize contamination, reagents should be prepared
          directly in their designated containers where possible.

          7.2.1  Acetic acid, glacial  (sp. gr. 1.05).

          7.2.2  Ammonium hydroxide (20%).

          7.2.3  Ammonium acetate buffer 1M, pH 5.5 - Add 58 ml (60.5 g) of
                 glacial acetic acid to 600 ml of ASTM type I water.  Add
                 65 ml (60 g) of 20% ammonium hydroxide and mix.  Check the pH
                 of the resulting solution by withdrawing a small aliquot and
                 testing with a calibrated pH meter, adjusting the solution to
                 pH 5.5 ± 0.1 with small volumes of acetic acid or ammonium
                 hydroxide as necessary.  Cool and dilute to 1 L with ASTM
                 type I water.

          7.2.4  Ammonium acetate buffer 2M, pH 5.5 - Prepare as for Sect.
                 7.2.3 using 116 ml (121 g) glacial acetic acid and 130 ml
                 (120 g) 20% ammonium  hydroxide, diluted to 1000 ml with ASTM
                 type I water.

                 NOTE: The ammonium acetate buffer solutions may be further
                 purified by passing them through the chelating column at a
                 flow rate of 5.0 mL/min.  With reference to Figure 1, pump
                 the buffer solution through the column using pump PI, with
                 valves A and B off and valve C on.  Collect the purified
                 solution in a container at the waste outlet.  Following this,
                 elute the collected contaminants from the column using 1.25M
                 nitric acid for 5 min at a flow rate of 4.0 mL/min.

          7.2.5  Nitric acid, concentrated  (sp.gr. 1.41).

                 7.2.5.1 Nitric acid 1.25M - Dilute 79 mL  (112 g) cone, nitric
                         acid to 1000  mL with ASTM type I water.

                 7.2.5.2 Nitric acid 1% - Dilute 10 mL cone, nitric acid to
                         1000 mL with  ASTM type I water.

                 7.2.5.3 Nitric acid (1+1) - Dilute 500 mL cone, nitric acid
                         to 1000 mL with ASTM type I water.

                 7.2.5.4 Nitric acid (1+9) - Dilute 100 mL cone, nitric acid
                         to 1000 mL with ASTM type I water.


                                       159


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     7.2.6  Oxalic acid dihydrate (CASRN 6153-56-6), 0.2M - Dissolve
            25.2 g reagent grade C2Hp04.2HpO in 250 ml ASTM type I water
            and dilute to 1000 ml with ASTM type I water.  CAUTION -
            Oxalic acid is toxic, handle with care.

7.3  STANDARD STOCK SOLUTIONS - May be purchased from a reputable
     commercial source or prepared from ultra high-purity grade chemicals
     or metals (99.99 - 99.999% pure).  All salts should be dried for one
     hour at 105°C, unless otherwise specified.  (CAUTION - Many metal
     salts are extremely toxic if inhaled or swallowed.  Wash hands
     thoroughly after handling).  Stock solutions should be stored in
     plastic bottles.  The following procedures may be used for preparing
     standard stock solutions:

     NOTE: Some metals, particularly those which form surface oxides
     require cleaning prior to being weighed.  This may be achieved by
     pickling the surface of the metal in acid.  An amount in excess of
     the desired weight should be pickled repeatedly, rinsed with water,
     dried and weighed until  the desired weight is achieved.

     7.3.1  Cadmium solution, stock 1 ml = 1000 jug Cd: Pickle cadmium
            metal  in (1+9) nitric acid to an exact weight of 0.100 g.
            Dissolve in 5 ml  (1+1)  nitric acid, heating to effect
            solution.   Cool  and dilute to 100 ml with ASTM type I water.

     7.3.2  Cobalt solution,  stock 1 mL = 1000 /zg Co: Pickle cobalt
            metal  in (1+9) nitric acid to an exact weight of 0.100 g.
            Dissolve in 5 ml  (1+1)  nitric acid, heating to effect
            solution.   Cool  and dilute to 100 ml with ASTM type I water.

     7.3.3  Copper solution,  stock 1 ml = 1000 /zg Cu: Pickle copper
            metal  in (1+9) nitric acid to an exact weight of 0.100 g.
            Dissolve in 5 ml  (1+1)  nitric acid, heating to effect
            solution.   Cool  and dilute to 100 ml with ASTM type I water.

     7.3.4  Indium solution,  stock  1 mL = 1000 fig In: Pickle indium metal
            in (1+1)  nitric acid to  an exact weight of 0.100 g.   Dissolve
            in 10  mL (1+1) nitric acid,  heating to  effect solution.   Cool
            and dilute to 100 mL with ASTM type I water.

     7.3.5  Lead solution, stock 1 mL = 1000 /ng Pb: Dissolve 0.1599 g
            PbN03  in 5 mL  (1+1) nitric acid.  Dilute  to 100 mL with ASTM
            type I water.

     7.3.6  Nickel  solution,  stock  1  mL  = 1000  jzg Ni: Dissolve 0.100 g
            nickel  powder in  5 mL cone,  nitric  acid,  heating  to  effect
            solution.   Cool and dilute  to 100  mL with ASTM type  I water.

     7.3.7  Terbium solution,  stock  1  mL  =  1000 /zg  Tb:  Dissolve 0.1176 g
            Tb407 in 5 mL cone, nitric acid, heating to effect solution.
            Cool and dilute to 100 mL with  ASTM type  I  water.
                                160

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7.4
7.5
7.6
7.3.8  Uranium solution, stock 1 ml = 1000 jug U: Dissolve 0.2110 g
       UOp(N03)2.6H20 (DO NOT DRY) in 20 mL ASTM type I water and
       dilute to 100 ml with ASTM type I water.

7.3.9  Vanadium solution, stock 1 ml = 1000 jug V: Pickle vanadium
       metal in (1+9) nitric acid to an exact weight of 0.100 g.
       Dissolve in 5 ml (1+1) nitric acid, heating to effect
       solution.  Cool and dilute to 100 ml with ASTM type I water.

7.3.10 Yttrium solution, stock 1 ml = 1000 /zg Y: Dissolve 0.1270 g
       Y20,  in  5 ml  (1+1)  nitric  acid,  heating  to effect  solution.
       Cool and dilute to 100 ml with ASTM type I water.

MULTI-ELEMENT STOCK STANDARD SOLUTION - Care must be taken in the
preparation of multi-element stock standards that the elements are
compatible and stable.  Originating element stocks should be checked
for the presence of impurities which might influence the accuracy of
the standard.  Freshly prepared standards should be transferred to
acid cleaned, new FEP or HOPE bottles for storage and monitored
periodically for stability.  A multi-element stock standard solution
containing the elements, cadmium, cobalt, copper, lead, nickel,
uranium and vanadium (1 mL = 10 /jg) may be prepared by diluting 1 mL
of each single element stock in the list to 100 mL with ASTM type I
water containing 1% (v/v) nitric acid.

7.4.1  Preparation of calibration standards - Fresh multi-element
       calibration standards should be prepared weekly.  Dilute the
       stock multi-element standard solution in 1% (v/v) nitric acid
       to levels appropriate to the required operating range.  The
       element concentrations in the standards should be
       sufficiently high to produce good measurement precision and
       to accurately define the slope of the response curve.   A
       suggested mid-range concentration is 10 /*g/L.

BLANKS - In addition to the laboratory fortified blank, two types of
blanks are required for this method.  A calibration blank is used to
establish the analytical calibration curve, and the laboratory
reagent blank is used to assess possible contamination from the
sample preparation procedure.
     7.5.1  Calibration blank - Consists of
            type I water.
                                          (v/v) nitric acid in ASTM
7.5.2  Laboratory reagent blank (LRB) - Must contain all the
       reagents in the same volumes as used in processing the
       samples.  The LRB must be carried through the entire sample
       digestion and preparation scheme.

TUNING SOLUTION - This solution is used for instrument tuning and
mass calibration prior to analysis (Sect. 9.2).  The solution is
prepared by mixing nickel, yttrium, indium, terbium and lead stock
                                 161

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          solutions (Sect. 7.3) in 1% (v/v) nitric acid to produce a
          concentration of 100 /tg/L of each element.

     7.7  QUALITY CONTROL SAMPLE (QCS) - A quality control sample having
          certified concentrations of the analytes of interest should be
          obtained from a source outside the laboratory.  Dilute the QCS if
          necessary with 1% nitric acid, such that the analyte concentrations
          fall within the proposed instrument calibration range.

     7.8  LABORATORY FORTIFIED BLANK (LFB)- To an aliquot of LRB, add aliquots
          from the multi-element stock standard (Sect. 7.4) to produce a final
          concentration of 10 fig/I for each analyte.  The fortified blank must
          be carried through the entire sample pretreatment and analytical
          scheme.

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  For the determination of total recoverable elements in aqueous
          samples, acidify with (1+1) nitric acid at the time of collection to
          a pH of less than two.  The sample should not be filtered prior to
          analysis.

          NOTE: Samples that cannot be acid preserved at the time of
          collection because of sampling limitations or transport
          restrictions, should be acidified with nitric acid to pH < 2 upon
          receipt in the laboratory.   Following acidification, the sample
          should be held for 16 h before withdrawing an aliquot for sample
          processing.

9.   CALIBRATION AND STANDARDIZATION

     9.1  Initiate proper operating configuration of ICP-MS instrument and
          data system.  Allow a period of not less than 30 min for the
          instrument to warm up.  During this process conduct mass calibration
          and resolution checks using the tuning solution.  Resolution at low
          mass is indicated by nickel isotopes 60,61,62.  Resolution at high
          mass is indicated by lead isotopes 206,207,208.  For good
          performance  adjust spectrometer resolution to produce a peak width
          of approximately 0.75 amu at 5% peak height.  Adjust mass
          calibration  if it has shifted by more than 0.1 amu from unit mass.

     9.2  Instrument stability must be demonstrated by analyzing the tuning
          solution (Sect.  7.6) a minimum of five times with resulting relative
          standard deviations of absolute signals for all analytes of less
          than 5%.

     9.3  Prior to initial  calibration,  set up proper instrument software
          routines for quantitative analysis and connect the ICP-MS instrument
          to the preconcentration apparatus.  The instrument must be
          calibrated for the analytes of interest using the calibration blank
          (Sect. 7.5.1) and calibration standard (Sect.  7.4.1) prepared at one
          or more concentration levels.   The calibration solutions should be

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          processed through the preconcentration system using the procedures
          described in Sect. 11.

     9.4  Demonstration and documentation of acceptable initial calibration is
          required before any samples are analyzed and is required
          periodically throughout sample analysis as dictated by results of
          continuing calibration checks.  After initial calibration is
          successful, a calibration check is required at the beginning and end
          of each period during which analyses are performed and at requisite
          intervals.

          9.4.1  After the calibration has been established, it must be
                 initially verified for all analytes by analyzing the QCS
                 (Sect. 7.7).  If measurements exceed ± 15% of the
                 established QCS value, the analysis should be terminated, the
                 source of the problem identified and corrected, the
                 instrument recalibrated and the new calibration verified
                 before continuing analyses.

          9.4.2  To verify that the instrument is properly calibrated on a
                 continuing basis, run the calibration blank (Sect. 7.5.1) and
                 calibration standards (Sect. 7.4.1) as surrogate samples
                 after every ten analyses.  The results of the analyses of the
                 standards will indicate whether the calibration remains
                 valid.  If the indicated concentration of any analyte
                 deviates from the true concentration by more than 15%,
                 reanalyze the standard.  If the analyte is again outside the
                 15% limit, the instrument must be recalibrated and the
                 previous ten samples reanalyzed.   The instrument responses
                 from the calibration check may be used for recalioration
                 purposes.

     9.5  INTERNAL STANDARDIZATION - Internal standardization should be used
          in all analyses to correct for instrument drift.   Internal standards
          may be added directly to the samples and standards prior to
          preconcentration or by mixing with the chelating  column carrier
          effluent prior to nebulization using a peristaltic pump and a mixing
          coil.  Information on the use of internal  standards may be found in
          Method 200.8(1).  NOTE: Lithium and bismuth should not be used as
          internal  standards using the direct addition method as they are not
          efficiently concentrated on the imino-diacetate  column.

10.   QUALITY CONTROL

     10.1 Each laboratory using this method is required to  operate a formal
          quality control  (QC)  program.   The minimum requirements of this
          program consist of an initial  demonstration of laboratory
          capability,  and the analysis of laboratory reagent blanks, fortified
          blanks and samples as a continuing check on performance.   The
          laboratory should maintain performance records that define the
          quality of the data generated.


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10.2 INITIAL DEMONSTRATION OF PERFORMANCE

     10.2.1 The initial demonstration of performance is used to
            characterize instrument performance (method detection limits
            and linear calibration ranges) for analyses conducted by this
            method.

     10.2.2 Method detection limits (MDL) should be established for all
            analytes, using reagent water (blank)  fortified at a
            concentration of two to five times the estimated detection
            limitc }.  To determine MDL values, take seven replicate
            aliquots of the fortified reagent water and process through
            the entire analytical method.  Perform all  calculations
            defined in the method and report the concentration values in
            the appropriate units.  Calculate the MDL as follows:

                 MDL = (t) x (S)

            where, t =   Student's t value for a 99% confidence level and
                         a standard deviation estimate  with n-1 degrees
                         of freedom [t = 3.14 for seven replicates].

                   S =   standard deviation of the replicate analyses.

            MDLs should be determined every six months  or whenever a
            significant change in background or instrument response is
            expected.

     10.2.3 Linear calibration ranges - The upper limit of the linear
            calibration range should be established for each analyte.
            Linear calibration ranges should be determined every six
            months or whenever a significant change in  instrument
            response is expected.

10.3 ASSESSING LABORATORY PERFORMANCE - REAGENT AND FORTIFIED BLANKS

     10.3.1 Laboratory reagent blank (LRB) - The laboratory must analyze
            at least one LRB (Sect. 7.5.2) with each set of samples.  LRB
            data are used to assess contamination  from  the laboratory
            environment.   If an analyte value in the LRB exceeds its
            determined MDL,  then laboratory or reagent  contamination
            should be suspected.  Any determined source of contamination
            should be corrected and the samples reanalyzed.

     10.3.2 Laboratory fortified blank (LFB) - The laboratory must
            analyze at least one LFB (Sect.  7.8) with each batch of
            samples.  Calculate accuracy as  percent recovery (Sect.
            10.4.2) If the recovery of any analyte falls outside the
            control limits (Sect. 10.3.3), that analyte is judged out of
            control, and the source of the problem should be identified
            and resolved before continuing analyses.
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     10.3.3 Until  sufficient LFB data become available from within  the
            laboratory (usually a minimum of 20 to 30 analyses),  the
            laboratory should assess laboratory performance against
            recovery limits of 85-115%.   When sufficient internal
            performance data becomes available, develop control  limits
            from the percent mean recovery (x)  and the standard  deviation
            (S)  of the mean recovery.  These data are used to establish
            upper and lower control  limits as follows:

                  UPPER CONTROL LIMIT * x + 3S
                  LOWER CONTROL LIMIT = x - 3S

            After each five to ten new recovery measurements, new control
            limits should be calculated using only the most recent  twenty
            to thirty data points.

10.4 ASSESSING ANALYTE RECOVERY - LABORATORY FORTIFIED SAMPLE MATRIX

     10.4.1 The laboratory must add a known amount of each analyte  to a
            minimum of 10% of the routine samples or one sample  per
            sample set, whichever is greater.  The analyte concentrations
            should be the same as those used in the LFB (Sect. 10.3.2).
            Over time, samples from all  routine sample sources should be
            fortified.

     10.4.2 Calculate the percent recovery for each analyte, corrected
            for the concentrations measured in the unfortified sample,
            and compare these values to the control limits established in
            Sect. 10.3.3 for the analyses of LFBs.  Recovery calculations
            are not required if the concentration of the analyte added is
            less than 10% of the sample concentration.  Percent  recovery
            may be calculated in units appropriate to the matrix, using
            the following equation:

                   cs - c
              R = 	  x 100
            where,   R  = percent recovery
                     Cs = fortified sample concentration
                     C  = sample concentration
                     s  = concentration equivalent of
                          fortifier added to sample.

     10.4.3 If recovery of any analyte falls outside the designated range
            and laboratory performance for that analyte is shown to be in
            control (Sect. 10.3), the recovery problem encountered with
            the fortified sample is judged to be matrix related, not
            system related.  The result for that analyte in the
            unfortified sample must be labelled "suspect/matrix" to
            inform the data user that the results are suspect due to
            matrix effects.

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11.  PROCEDURE

    11.1 SAMPLE PREPARATION - TOTAL RECOVERABLE ELEMENTS

         11.1.1 For the determination of total  recoverable elements,  take a
                100 mL aliquot from a well  mixed,  acid preserved sample and
                transfer to a 250-mL Griffin beaker.   Add 1 mL of
                concentrated nitric acid and heat  on  a hot plate at 85°C
                until  the volume has been reduced  to  approximately 25 mL,
                ensuring that the sample does not  boil.   Cover the beaker
                with a watch glass and reflux for  30  min.   Slight boiling may
                occur but vigorous boiling  should  be  avoided.   Allow to cool
                and dilute to 100 mL with ASTM  type I water.   Centrifuge the
                sample or allow to stand overnight to separate insoluble
                material.

    11.2 Prior to  first use,  the preconcentration  system should be thoroughly
         cleaned and decontaminated using 0.2M  oxalic acid.

         11.2.1 Place  approximately 500 mL  0.2M oxalic acid in the eluent  and
                carrier solution containers and fill  the sample loop  with
                0.2M oxalic acid using the  sample  pump (P4)  at a flow rate of
                3-5 mL/min.   With the preconcentration system  disconnected
                from the ICP-MS instrument,  use the pump program sequence
                listed in Table 2,  to flush the complete system with  oxalic
                acid.   Repeat the flush sequence three times.

         11.2.2 Repeat the sequence described in Sect.  11.2.1  using  1.25M
                nitric acid  and again using ASTM type I  water  in place  of  the
                0.2M oxalic  acid.

         11.2.3 Rinse  the containers  thoroughly with  ASTM  type I  water,  fill
                them with their designated  reagents (see  Figure 1) and  run
                through  the  sequence  in Table 2  once  to  prime  the pump  and
                all  eluent lines  with  the correct  reagents.

    11.3  Initiate  ICP-MS  instrument  operating configuration.   Tune and
         calibrate  the instrument  for  the analytes  of interest  (Sect. 9).

    11.4  Establish  instrument  software  run  procedures  for  quantitative
         analysis.    Because the  analytes are eluted from the preconcentration
         column  in  a transient manner,  it is recommended that  the  instrument
         software  is configured  in  a rapid  scan/peak  hopping mode.

    11.5  Reconnect  the preconcentration  system to the  ICP-MS instrument.
        With valves A and B  in the off  position and  valve C in the on
        position,   load sample through the sample loop to waste using pump P4
        for 4 min   at 4 mL/min.  Switch  on the carrier pump (P3)  and pump 1%
        nitric acid to the nebulizer of the ICP-MS instrument  at a flow rate
        of 0.8-1.0 mL/min.
                                    166

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   11.6 Switch on the buffer pump (P2),  and pump 2M ammonium acetate at a
        flow rate of 1 mL/min.

   11 7 Preconcentration of the sample may be achieved by running through an
        eluent pump program (PI) sequence similar to that illustrated in
        Table 2.  The exact timing of this sequence should be modified
        according to the internal volume of the connecting tubing and the
        specific hardware configuration used.

        11.7.1 Inject sample - With valves A, B and C on, load sample from
               the loop onto the column using 1M ammonium acetate for 4.5
               min at 4.0 mL/min.  The analytes are retained on the column,
               while the majority of the matrix is passed through to waste.

        11.7.2 Elute analytes - Turn off valves A and B and begin eluting
               the analytes by pumping 1.25M nitric acid through the column
               at 4.0 mL/min, then turn off valve C and pump the eluted
               analytes into  the  ICP-MS instrument at 1.0 mL/min.   Initiate
               ICP-MS software data acquisition and integrate the eluted
               analyte profiles.

        11.7.3 Column Reconditioning - Turn on  valve C to direct column
               effluent to waste, and pump  1.25M nitric acid, 1M ammonium
                acetate, 1.25M nitric acid  and  1M ammonium acetate
                alternately through the column  at 4.0 mL/min.  During this
                process, the next  sample can  be  loaded into  the  sample  loop
                using the  sample  pump  (P4).

    11.8 Repeat  the  sequence described  in  Sect.  11.7 for  each  sample to be
        analyzed.   At the end of the  analytical  run leave the column filled
        with 1M ammonium  acetate buffer  until  it  is next  used.

    11.9 Samples  having  concentrations  higher than  the established  linear
        dynamic range should  be diluted  into range and re-analyzed.

12.  CALCULATIONS

    12.1 Analytical  isotopes and elemental  equations  recommended for sample
        data calculations are listed in  Table 3.   Sample data should be
         reported in units of Mg/L.   Do not report element concentrations
         below the determined MDL.

    12.2 For data values less than ten,  two significant  figures  should be
         used for reporting element concentrations.  For  data values greater
         than or equal to ten, three significant figures  should be used.

    12.3 Reported values should be calibration blank subtracted.  If
         additional dilutions were made to any samples,  the appropriate
         factor should be applied to the calculated sample concentrations.
                                     167

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    12.4 Data values should be corrected for instrument drift by the
         application of internal standardization.  Corrections for
         characterized spectral interferences should be applied to the data.

    12.5 The QC data obtained during the analyses provide an indication of
         the quality of the sample data and should be provided with the
         sample results.

13.  PRECISION AND ACCURACY

    13.1 Experimental conditions used for single laboratory testing of the
         method are summarized in Table 4.

    13.2 Data obtained from single laboratory testing of the method are
         summarized in Tables 5 and 6 for two reference water samples
         consisting of National Research Council  Canada (NRCC),  Estuarine
         Water (SLEW-1) and Seawater (NASS-2).   The samples were prepared
         using the procedure described in Sect.  11.2.1.  For each matrix,
         three replicates  were analyzed and the  average of the replicates
         used for determining the sample concentration for each  analyte.   Two
         further sets of three replicates were fortified at different
         concentration levels, one set at 0.5 /zg/L,  the other at 10 /xg/L.
         The sample concentration,  mean percent  recovery,  and the relative
         standard deviation of the fortified replicates are listed for each
         method  analyte.   The reference material  certificate values are also
         listed  for comparison.
                                    168

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14.  REFERENCES

    1.    USEPA Method 200.8, Office of Research and Development, USEPA,
         Cincinnati, Ohio, August 1990.

    2.    A. Siraraks, H.M. Kingston and J.M. Riviello,
         Anal Chem. 62 1185 (1990).

    3.    E.M. Heithmar, T.A. Hinners, J.T. Rowan and J.M. Riviello,
         Anal Chem. 62 857  (1990).

    4.    "OSHA Safety and Health Standards, General Industry,"  (29 CFR 1910),
         Occupational Safety and Health Administration, OSHA 2206, revised
         January 1976.

    5.    "Proposed OSHA Safety and Health Standards, Laboratories,"
         Occupational Safety and Health Administration, Federal
         Register, July 24, 1986.

    6.    Code of Federal  Regulations 40, Ch. 1, Pt. 136 Appendix B.
                                     169

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TABLE 1: TOTAL RECOVERABLE METHOD DETECTION LIMITS FOR REAGENT WATER
            ELEMENT
  RECOMMENDED
ANALYTICAL MASS
                                                MDL
Cadmium
Cobalt
Copper
Lead
Nickel
Uranium
Vanadium
111
59
63
206,207,208
60
238
51
0.041
0.021
0.023
0.074
0.081
0.031
0.014
                               170

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TABLE 2: Eluent PUMP PROGRAMMING SEQUENCE FOR PRECONCENTRATION
                         OF TRACE ELEMENTS
Time
(min)
0.0
4.5
5.1
5.5
7.5
8.0
10.0
11.0
12.5
Flow
mL/min
4.0
4.0
1.0
1.0
4.0
4.0
4.0
4.0
0.0
Eluent

1M ammonium acetate
1.25M nitric acid
1.25M nitric acid
1.25M nitric acid
1.25M nitric acid
1M ammonium acetate
1.25M nitric acid
1M ammonium acetate

Valve
A,B
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Valve
C
ON
ON
ON
OFF
ON
ON
ON
ON
ON
                                  171

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        TABLE 3: RECOMMENDED ANALYTICAL ISOTOPES AND ELEMENTAL  EQUATIONS
                           FOR DATA CALCULATIONS
Element    Isotope
      Elemental Equation
                                                                        Note
Cd    106,108,111,114
Co    59
Cu    63,65
Pb    206,207.208
Ni    60
U     238
V     51
(1.000)(111C)-(1.073)[(108C)-(0.712)(106C)]
(1.000)(59C)
(1.000)(63C)
(1.000)(206C)+(1.000)(207C)+(1.000)(208C)
(1.000)(60C)
(1.000)(238C)
(1.000)(51C)
(1)
(2)
      C  - calibration blank subtracted counts  at  specified  mass
     (1) - correction for MoO interference. An  additional  isobaric
           elemental correction should be made  if  palladium  is  present.
    (Z) - allowance for isotopic variability of lead  isotopes.
     NOTE: As a minimum, all isotopes listed should be monitored.  Isotopes
          recommended for analytical determination are underlined.
                                     172

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TABLE 4: EXPERIMENTAL CONDITIONS FOR SINGLE LABORATORY VALIDATION
     Chromatography

     Instrument
     Preconcentration column
Dionex chelation system
Dionex MetPac CC-1
     ICP-MS  Instrument Conditions

     Instrument
     Plasma  forward  power
     Coolant flow  rate
     Auxiliary flow  rate
     Nebulizer flow  rate

     Internal  standards

     Data Acquisition

     Detector mode
     Mass range
     Dwell time
     Number of MCA channels
     Number of scan  sweeps
VG PlasmaQuad Type I
1.35 kW
13.5 L/min
0.6 L/min
0.78 L/min

Sc, Y, In, Tb
 Pulse  counting
 45-240 amu
 160 /is
 2048
 250
                                  173

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               TABLE 5: PRECISION AND RECOVERY DATA FOR ESTUARINE WATER (SLEW-1)
Analyte
Cd
Co
Cu
Pb
Ni

mmm
Certificate
(09/L)
0.018
0.046
1.76
0.028
0.743
••»•»
••••••IMBMB
Sample
Concn.
(09/L)
<0.041
0.078
1.6
<0.074
0.83
1.1
1.4
Spike
Addition
(0g/L)
0.5
0.5
0.5
0.5
0.5
0.5
0.5
Average
Recovery
(%)
94.8
102.8
106.0
100.2
100.0
96.7
100.0
^••^•^
RSD
(%)
9.8
4.0
2.7
4.0
1.5
7.4
3.2
^^^_^^^__
••^^^•^^•^^••^H
Spike
Addition
(09/L)
10
10
10
10
10
10
10
Average
Recovery
(%)
99.6
96.6
96.0
106.9
102.0
98.1
97.0
RSD
(°/o)
1.1
1.4
4.8
5.8
2.1
3.6
4.5
 — No certificate value
              TABLE  6:  PRECISION AND  RECOVERY DATA  FOR SEAWATER  (NASS-2)
Analyte
Cd
Co
Cu
Pb
Ni
U

Certificate
0.029
0.004
0.109
0.039
0.257
3.00
^™~
Sample
Concn.
(pg/L)
<0.041
<0.021
0.12
<0.074
0.23
3.0
1.7
Spike
Addition
(/KJ/L)
0.5
0.5
0.5
0.5
0.5
0.5
0.5
^•^•^•^^^n
Average
Recovery
101.8
98.9
95.8
100.6
102.2
94.0
104.0
(^•i^M^HI
RSD
1.0
3.0
2.3
8.5
2.3
0.7
3.4
^••^•^•^•••i
Spike
Addition
(fig/L)
10
10
10
10
10
10
10
•••••••^•M
Average
Recovery
96.4
99.2
93.1
92.1
98.2
98.4
109.2
mtmmm
(%*
3.7
1.7
0.9
2.6
1.2
1.7
3.7
— No certificate value
                                              174

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                     METHOD 200.11
       DETERMINATION OF METALS IN FISH TISSUE BY
INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROMETRY
          Theodore D.  Martin,  Eleanor  R.  Martin
                           and
                    Larry B. Lobring
               Inorganic Chemistry Branch
               Chemistry Research Division

                           and

                     Gerald D. McKee
                  Office of the Director
                      Revision 2.1
                       April  1991
       ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
           OFFICE OF RESEARCH AND DEVELOPMENT
           U.S.  ENVIRONMENTAL PROTECTION AGENCY
                 CINCINNATI, OHIO 45268
                            177

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                               METHOD 200.11

                  DETERMINATION OF METALS IN FISH TISSUE BY
           INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROMETRY

1.   SCOPE AND APPLICATION

     1.1  This method is an inductively coupled plasma (ICP)-atomic emission
          spectrometnc procedure for use in determination of naturally
          occurring and accumulated toxic metals in the edible tissue portion
          (fillet) of the fish.  The tissue must be taken from a fresh, not
          previously frozen,  fish to prevent analyte loss or tissue
          contamination due to cell  lysis and resulting fluid exchange.  The
          method is not intended to be used for analysis of dried fish tissue
          This method is applicable to the determination of the following
          metals:                                                        3
            Analvte
    1.2
    1.3
         Aluminum  (Al)
         Antimony  (Sb)
         Arsenic (As)
         Beryllium (Be)
         Cadmium (Cd)
         Chromium  (Cr)
         Copper (Cu)
         Lead  (Pb)
         Nickel (Ni)
         Selenium  (Se)
         Thallium  (Tl)
         Zinc  (Zn)
                                     Chemical Abstract Services
                                     Registry Numbers (CASRN)
                                             7429-
                                             7440-
                                             7440-
                                             7440-
                                             7440-
                                             7440-
                                             7440-
                                             7439-
                                             7440-
                                             7782-
                                             7440-
                                             7440-
-90-5
-36-0
-38-2
•41-7
•43-9
•47-3
50-8
92-1
02-0
49-2
28-0
66-6
 This  method  also  may be  used  for spectrochemical  determination of
 other elements  commonly  found in fish  tissue.   Specific analvtes
 included  are the  following:
          Analvte

         Calcium (Ca)
         Iron (Fe)
         Magnesium  (Mg)
         Phosphorus (P)
         Potassium  (K)
         Sodium (Na)
                                   Chemical Abstract  Services
                                   Registry Numbers (CAS  RN)

                                            7440-70-2
                                            7439-89-6
                                            7439-95-4
                                            7723-14-0
                                            7440-09-7
                                            7440-23-5
Specific instrumental operating conditions are given and should be
used whenever possible.  However, because of the differences
between various makes and models of spectrometers, the analyst
should follow the instrument manufacturer's instructions in
                                    178

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          adapting  the  instrument's operation to  approximate the recommended
          conditions  given  in  this method.

     1.4   Table  1 lists the recommended wavelengths with  locations  for
          background  correction  for the metals  presently  included  in  this
          method.   Also listed in Table 1  are typical  method detection  limits
          (MDLs)1 for certain  metals determined in fish tissue using
          conventional  pneumatic nebulization for sample  introduction into
          the ICP.

     1 5   Once the  tissue samples  have been collected, approximately  20 fish
          fillet samples including  the mandatory  quality  control  samples can
          be analyzed using this method during  the 1.5 day work period
          required  to complete the  analysis.

2.   SUMMARY OF METHOD

     21   A 1 to 2  g sample of fish tissue is taken from a fresh (not
          previously frozen) fish  and transferred to a preweighed, labeled
          polysulfone Oak Ridge type centrifuge tube.  The tissue is
          dissociated using tetramethylammonium hydroxide ' , low heat and
          vortex mixing.  The following day, the metals in the resulting
          colloidal  suspension are acid solubilized with nitric acid and heat,
          and then diluted with deionized, distilled water to a weight volume
          ratio equal to 1 g  fish tissue per 10 ml of solution.  The diluted
          sample is  vortex mixed,  centrifuged and finally the acidified
          aqueous  solution  is analyzed by direct aspiration background
          corrected  ICP  atomic emission spectrometry.  The determined metal
          concentration  is  reported as microgram/gram (^g/g) wet  fish  tissue
          weight.

      2.2  The basis  of the  method determination  step  is the measurement of
          atomic emission  by  optical  spectroscopy.  The sample  is nebulized
          and the  aerosol  that  is produced  is transported to the   plasma  torch
          where excitation  occurs.  Characteristic atomic-line     emission
          specta are produced by a radio-frequency ICP.  The spectra  are
          dispersed  by a grating spectrometer  and the intensities  of the
          lines are  monitored by photomultiplier tubes.  The photocurrents
          from  the photomultiplier tubes  are processed and controlled  by  a
          computer system.   Background correction  is  required  to  compensate
          for the  variable background contribution of fish matrix and
          reagents to  the  analyte  determination. The location  recommended
          for background correction  for  each analyte is  given  in  Table 1.

 3.   DEFINITIONS

      3.1  FISH TISSUE - The skinless  edible muscle  tissue of  the  fish
           commonly referred to as  the fillet.
                                       179

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  3.2  METHOD DETECTION LIMIT (HDL)  - The minimum concentration  of  an
       analyte that can be identified,  measured  and  reported with 99%
       confidence that the analyte concentration is  greater than zero.

  3.3  CALIBRATION BLANK - A volume  of deionized,  distilled water
       containing all  reagents  used  to  prepare the tissue  for  analyses
       The calibration Manlr ic  a  ™™  e+,^,-^  and  is used to calibra{e
 3.4   FIELD  DUPLICATES  (FD1  and  FD2) - Two separate samples collected at
       the  same  time  and  place  under  identical circumstances and treated
       exactly the  same throughout field and laboratory procedures
       Analyses  of  FD1 and  FD2  give a measure of the precision associated
       with camniQ  ™-n^,_   preservation, and storage, as well as with
 3.5
      hdrSYt^?G-NT,BLAf,(LRB).T A"  a11quot  of  tetramethylammonium
      hydroxide  that  is  treated  exactly  as  a  sample including exposure to
      all  glassware,  equipment,  and  reagents  that  are used with other
      samples.   The LRB  is  used  to determine  if method analytes or other

                                n ^ lab°rat°ry  env1™"ment> ^agents,
                         .(FRB) I An emP^ Oak Rid9e Polysulfone sample
                      ?  1S ^eated as a sample in all  respects, including
                  samP]in9 site conditions,  storage, preservation,  and  all
      analytical procedures.  The purpose of the FRB is to determine if
      method analytes or other interferences are present in the field
      environment (Sect. 10.3.2).

 3.7  LABORATORY PERFORMANCE CHECK SOLUTION  (LPC)  -  A solution  of method
      analytes used to evaluate the performance of the  instrument system
      with respect to a defined set of method  criteria  (Sect. 7.10.1).
3'8
      tABShAThRif FORTIFIED.BLANK (LFB)  - An  aliquot of tetramethylammonium
      to  which  known  quantities  of the  method  analytes are added  in the
      laboratory.   The  LFB  is  analyzed  exactly like a sample and  its
      tKhnifti! d?termine  whether the method  is in control and whether
      the laboratory  is  capable  of making accurate and precise
      measurements  at the required method detection limit (Sect.  10.3.4).
3'9
     tABSRif FORTI™ SAMPLE MATRIX  (LFM)  -  An  aliquot  of  fish  tissue
     to which known quantities  of the  method analytes  are added  in  the
                  T6 LFM-1S  aalzed  exactly  11k^  a samPle> and  Its
         n           *-            exactly 11k  a samPle> and Its
     purpose is to determine whether the sample matrix contributes bias
     to the analytical results.  The background concentrations of the
     analytes in the sample matrix must be determined in a separate

                                                              background
3.10 STOCK STANDARD SOLUTION - A concentrated solution containing a
     single certified standard that is a method analyte,  or a
                                 180

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          concentrated  solution  of  a  single  analyte prepared  in the laboratory
          with  an  assayed  reference compound.   Stock  standard solutions  are
          used  to  prepare  primary dilution standards  (Sect. 7.6).

     3.11  PRIMARY  DILUTION STANDARD SOLUTION -  A  solution  of  several  analytes
          prepared in the  laboratory  from stock standard solutions  and diluted
          as  needed to  prepared  calibration  solutions and  other needed analyte
          solutions (Sect. 7.7).

     3.12  CALIBRATION STANDARD (CAL)  - A solution prepared from the primary
          dilution standard solution.  The CAL  solutions are  used  to  calibrate
          the instrument response with respect  to analyte  concentration
          (Sect.  7.9).

     3.13  QUALITY CONTROL SAMPLE (QCS) - A solution  of method analytes of
          known concentrations which  is used to fortify an aliquot of LRB
          matrix.   The  QCS is obtained from  a source external to  the
          laboratory and used to check laboratory performance with externally
          prepared test materials  (Sect. 10.2.2).

4.   INTERFERENCES

     4.1  Occurrences of chromium contamination of biological samples from^
          the use of stainless  steel  have been reported in the literature.
          Use of special cutting implements and dissecting board made from
          materials that  are not of  interest is recommended.   Knife blades
          made of titanium with Teflon handles have been successfully used.

     4.2  Sample contamination  and losses are held to a minimum because the
          collected sample is preserved, processed and analyzed in the same
          polysulfone centrifuge tube.  However, the stability of metals  in
          the analysis  solution is not fully documented and  therefore, the
          sample  should be analyzed  within  24 h  after completion of the
          preparation procedure (Sects.  11.2 to  11.7).

     4.3  The processed sample  ready for analysis will contain a precipitate
          and possibly  floatable solids  as  a surface layer partially covering
          the analysis  solution.   Nevertheless,  physical  occlusion of metals
          in these  solids is  not expected.   Percent  recoveries of all metal
          concentrations  added, except  antimony,  are near or exceed 90%
          (Sect.  13.4.)

     4.4  Because all  samples are  diluted to the same weight volume  ratio
          (1 g/10 mL),  all  samples of the same type  of fish  tissue have
          similar concentrations of  the  major  constituents in the matrix.
          These major  constituent  elements  (Ca,  K, Mg, Na and P)  do  not
          suppress analyte signal  intensities  or cause interelement  spectral
          interferences for the wavelengths and  analytical conditions
          recommended.   However, these elements  represent a  small  portion
           (<1500mg/L)  of the approximate 5% dissolved  solids in the  solution
          matrix that  is  aspirated.   Tetramethylammonium  hydroxide accounts
          for  the majority of the  matrix and is  believed  to  undergo  chemical

                                       181

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4.5
4.6
 change  during  sample preparation  (Sect.  11);  this  causes  slight
 shifts  in  background intensity  and molecular  band  contribution to
 wavelength signals  near  190  nanometers  (nm).  Although  background
 correction adjacent to the wavelength will compensate for the
 majority of the  broad band interferences, LRB (Sect. 3.5) sub-
 traction must  be used to provide  the additional correction needed
 for the wavelengths of As (193.7  nm), Se  (196.0 nm) and Th
 (190.8  nm).

 Dissolved  solids  exceeding 1500 to 2000 mg/L  can cause  a  reduction
 in atomic  emission  signal intensities.   In this method, because the
 calibration  standard  and sample solutions both contain  approximately
 5% dissolved solids,  any resulting matrix effect is minimized.  Of
 greater importance  is that partial clogging of the instrument
 nebulizer  and torch  impinger tube does not occur.

The number of interelement spectral interferences  in the  fish
tissue  matrix is minimal.  Listed below are all  interelement
correction factors determined for the wavelengths and background
correction locations recommended in this method.  Although these
factors are only applicable to the instrument used in the
development of this method,  they can be used as  a guide and are
evidence that,  except for fortified samples,  most fish tissue
analyses do not require  interelement correction  factors.  It
should be noted that if a listed interferant is  present at a
concentration of 10 fig/g or less, its apparent concentration on the
analyte channel is less than  the analyte's determined MDL.

             INTERELEMENT CORRECTION FACTORS

             Analvte   Interferant  Factor
                    As
                    As
                    As
                    Cr
                    Cr
                    Cr
                    Pb
                    Pb
                    Sb
                    Sb
                    Se
                    Zn
                    Zn
                          Al
                          Be
                          Ni
                          Cu
                          Ni
                          Fe
                          Al
                          Cu
                          Cr
                          Ni
                          Fe
                          Cu
                          Ni
+0.0080
-0.0027
-0.0056
-0.0007
+0.0006
-0.0003
-0.234
+0.0008
+0.0150
-0.0087
-0.0205
+0.0013
+0.0039
    A 1 Mg/g concentration of interferant would either add to or
    subtract  from the analyte an apparent concentration in jug/g  equal
    to the value of the correction factor.
                                182

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    4.7  The  following  "off-the-line"  background  correction  locations-should
         be avoided  because  of  existing  spectral  interference.

         4.7.1   The  low side (- 0.07 nm)  of the 190.8  nm  Th  wavelength has  a
                 spectral  interference  from phosphorus.

         4.7.2   Background correction  on the low  side  of  the 193.7  nm As
                 wavelength below -  0.06  nm may result  in  a severe negative
                 bias.

         4.7.3   The  high side (+ 0.07  nm) of the  196.0 nm Se wavelength has a
                 severe  undefined spectral interference originating  from the
                 tetramethylammonium hydroxide.

         4.7.4   Background correction  on the low  side  of  the 259.9  nm Fe
                 wavelength below -  0.06  nm may result  in  spectral
                 interference from 259.8  nm Fe wavelength.

         4.7.5   The  low side (- 0.05 nm) of the  308.2  nm  Al  wavelength has  a
                 spectral interference  from argon.

         4.7.6   The  low side (- 0.04 nm) of the  213.8  nm  Zn wavelength
                 read in the 2nd order  has a weak spectral interference from
                 magnesium.

5.   SAFETY

     5.1  All  personnel  handling environmental samples  known to contain or to
          have been in contact with human waste should  be  immunized against
          known  disease causative agents.

     5.2  Precautions should also be taken to minimize potential bacterial
          infections from handling and dissecting fish.  Basic good house-
          keeping and sanitation practices and use of rubber or plastic
          gloves are recommended.

     5.3  Mobile and remote  sampling locations should be equipped with a
          communication  system  to summon  help  in case of an emergency.  It  is
          recommended that field personnel not work alone.

     5.4  Material safety data  sheets  for all  chemical  reagents should be
          available to  and understood  by  all personnel  using this method.
          Specifically,  tetramethylammonium  hydroxide  (25%) and concentrated
          nitric acid are moderately toxic  and extremely  irritating to skin
          and mucus membranes.  Use these reagents in  a hood whenever  possible
          and if eye or skin contact occurs, flush with large volumes  of
          water.  Always wear safety glasses or a shield  for eye protection
          when working  with  these reagents.

6.   APPARATUS AND EQUIPMENT

     6.1  TISSUE DISSECTING  EQUIPMENT

                                       183

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      6.1.1.  Dissecting Board:  Polyethylene or other inert,  nonmetallic
             material;  any non-wetting,  easy-to-clean or disposable
             surface is suitable.   Adhesive backed Teflon or plastic
             film may be convenient to use.

      6.1.2  Forceps:  Plastic,  Teflon or Teflon coated.

      6.1.3  Surgical  Blades: Disposable stainless steel  with stainless
             steel  or plastic handle (Sect. 4.1).

      6.1.4  Scissors:   Stainless  steel.

      6.1.5  Plastic bags  with  watertight seal,  metal  free.

      6.1.6  Label  tape:   Self-adhesive,  vinyl-coated  marking tape,
             solvent resistant,  usable from -23°C  to  122°C.

      6.1.7  Polyvinyl  chloride  or rubber gloves,  talc-free.

6.2   Labware - All  reusable glassware,  polysulfone and Teflon containers
      must  be soaked and washed  with  detergent,  rinsed with  tap water,
      soaked  for  4  h in  a  mixture  of  dilute nitric and hydrochloric  acid
      (1+2+9), rinsed again with tap  water followed by deionized,
      distilled water  (Sect. 7.1)  and oven drying.  The use  of chromic
      acid  must be  avoided.

      6.2.1   Glassware:  Class A volumetric  flasks of various volumes,
             assorted calibrated pipettes  and beakers.

      6.2.2   Oak  Ridge type centrifuge tubes:  30-mL capacity, polysulfone
             tube with polypropylene  screw closure (available from most
             suppliers of  laboratory  equipment).

      6.2.3   Storage bottles:  Narrow-mouth  bottles, Teflon  FEP
             (fluorinated  ethylene propylene) with Tefzel ETFE
             (ethylene tetrafluorethylene) screw closure, 125-mL and
             250-mL  capacities.

     6.2.4  Wash bottle:  One-piece  stem, Teflon FEP bottle with
            Tefzel  ETFE screw closure, 125-mL capacity.

6.3  SAMPLE PROCESSING EQUIPMENT

     6.3.1  Air Displacement Pipetter:  Digital pipet capable of
            delivering volumes  ranging from 0.1 to 2500  microliters with
            an  assortment of high quality disposable pipet tips.

     6.3.2  Hot Plate:   Ceramic top, graduated dial  90°C to 450°C
            (Corning PC100 or equivalent).
                                184

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         6.3.3  Test tube rack:  Polycarbonate tube size 25-30 mm, 3 x 8
                array.

         6.3.4  Single pan balance capable of weighing to the nearest 0.01 g.


         6.3.5  Analytical balance capable of weighing to the nearest
                0.0001 g.

         6.3.6  Vortex mixer with neoprene mixing head and built-in rheostat
                control.

         6.3.7  Centrifuge:  Steel cabinet with guard bowl, capable of
                reaching  2000  r.p.m. compatible with centrifuge tubes
                (Sect. 6.2.3), electric timer and brake.  (International
                Centrifuge, Universal Model UV or equivalent.)

         6.3.8  Drying oven:   Gravity convection oven, with thermostatic
                control capable  of maintaining 65°C and  100°C ± 5°C with  an
                interior  dimension of no  smaller than 14" x 6" x  6".

     6.4    ANALYTICAL  INSTRUMENTATION

         6.4.1  The  ICP instrument may be a simultaneous or sequential
                spectrometer  system that  uses ionized argon gas as  the
                plasma.   However, the system and the processing of
                background  corrected  signals must be computer controlled.
                The  instrument must be capable of meeting and complying with
                the  requirements and  description of the  technique given  in
                Sect.  2.2.  The  instrument must  be equipped with  a  nebulizer
                and  torch impinger  tube  that has an orifice capable of
                accepting 5%  dissolved solids.

          6.4.2  A variable  speed peristaltic pump  is required to  deliver
                both standard and sample solutions to the nebulizer.

          6.4.3  The  use  of mass  flow  controllers to regulate  the  argon
                 flow rates,  especially through the nebulizer, are highly
                 recommended.   Their use  will provide more exacting  control  of
                 reproducible  plasma conditions.

7.   REAGENTS AND  CONSUMABLE MATERIAL

     7.1  Deionized,  distilled water:   Prepare  by passing distilled water
          through  a mixed bed  of cation  and anion exchange  resins.  Use
          deionized,  distilled water for  the preparation of  all  reagents and
          as dilution or rinse water.   The purity of  this water  must be
          equivalent to ASTM Type II reagent water of  Specification D 1193.

     7.2  Nitric acid (HN03),  cone,  (sp.gr. 1.41)  (CASRN  7697-37-2),  ACS
          reagent grade or equivalent.  Redistilled acid is  acceptable.


                                      185

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7.3
7.4
7.5
7.6
 7.2.1  Nitric acid, (1+1):  Add 500 mL cone. HNO, (Sect.  7.2)  to 400
        ml deionized, distilled water (Sect. 7.1) and dilute to 1 L.

 7.2.2  Nitric acid, (1 + 9):  Add 100 mL cone. HNO, (Sect.  7.2)  to
        400 mL deionized distilled water (Sect. 7.1) and dilute to
        X L *

 Hydrochloric acid (HC1), cone. (sp.  gr. 1.19,  CASRN 7647-01-0),
 ACS reagent  grade or equivalent.

 7.3.1  Hydrochloric acid,  (1+1):   Add 500 mL cone.  HC1  (Sect.  7.3)
        to 400 ml deionized,  distilled water (Sect.  7.1) and dilute
        to 1  L.

 Tetramethylammonium hydroxide [(CH3)4NOH],  (CASRN 75-59-2), TMAH 25%
 aqueous solution,  electronic grade 99.9999% (metals basis)  ALFA
 #20932  or equivalent.

 Ammonium hydroxide (NH,OH) (CASRN  1336-21-6), ACS reagent grade  or
 equivalent (sp.  gr.  0.902).

 Standard stock solutions may be purchased  or prepared from  ultra-
 high  purity  grade  chemicals  or metals.   All  salts must  be dried
 for 1 h at 105°C unless  specified  otherwise.   (CAUTION:  Wash  hands
 thoroughly after handling).   Typical  stock solution preparation
 procedures follow.

 NOTE:   Some  metals,  particularly those  which form surface oxides
 require cleaning prior to  being weighed.   This may  be achieved by
 pickling  the surface of  the  metal  in  acid.  An amount in excess  of
 the desired  weight should  be pickled  repeatedly, rinsed with water,
 dried and  weighed  until  the  desired weight  is achieved.

 7.6.1   Aluminum  solution,  stock (1 ml =  1000 p,g  Al)  - Pickle
        aluminum  metal in warm  (1+1) hydrochloric acid to an exact
        weight  of 0.100 g.  Dissolve in  an acid mixture of 5 mL
        (1+1)  hydrochloric  acid and 1 mL cone, nitric acid in a
        beaker.   Warm gently  to effect solution.  When solution is
        complete, transfer quantitatively to a 100-mL volumetric
        flask and dilute to the mark with deionized,  distilled water.
        Store the solution in a screwcap Teflon FEP storage bottle
        (Sect. 6.2.3).

7.6.2  Antimony solution, stock (1 mL = 1000 /xg Sb)  - Dissolve.
       0.100  g antimony powder (CASRN 7440-36-0)  in  2 mL (1+1)
       nitric acid and 0.5 mL cone, hydrochloric acid,  heating to
       effect solution.   Cool, add 20 mL deionized,  distilled water
       and 0.15 g tartaric acid.   Warm the solution  to  dissolve the
       white  precipitate.  Cool and dilute to 100 mL in  volumetric
       flask  with deionized distilled water.  Store  the  solution  in
       a screwcap Teflon  FEP  storage  bottle (Sect. 6.2.3).
                                186

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7.6.3  Arsenic solution, stock (1 ml = 1000 p.g As) - Dissolve
       0.1320 g arsenic trioxide (AsA)  (CASRN 1327-53-3)  in 50 ml
       deionized, distilled water ana l ml cone,  ammonium hydroxide.
       Heat gently to dissolve.  Acidify the solution with 2 ml
       cone, nitric acid and dilute to 100 ml in a volumetric flask
       with deionized, distilled water.  Store the solution in a
       screwcap Teflon FEP storage bottle (Sect.  6.2.3).

7.6.4  Beryllium solution stock (1 ml = 500 jug Be) - Do not dry.
       Dissolve 0.9830 g beryllium sulfate (BeS04«4H20)  in
       deionized, distilled water, add 1.0 ml cone, nitric acid and
       dilute to 100 ml in a volumetric flask with deionized,
       distilled water.  Store the solution in a screwcap Teflon FEP
       storage bottle (Sect. 6.2.3).

7.6.5  Cadmium solution stock  (1 ml = 1000 fj.g Cd) - Pickle cadmium
       metal in  (1+9) nitric acid to an exact weight of 0.100 g.
       Dissolve  in 4 ml cone, nitric acid, dilute to 100 ml in a
       volumetric flask with deionized, distilled water.  Store the
       solution  in a screwcap Teflon FEP storage bottle
       (Sect. 6.2.3).

7.6.6  Calcium solution stock  (1 ml = 1000 jug Ca) - Suspend
       0.2498 g  calcium carbonate (CaCOj) dried at 180°C for 1 h
       before weighing, in deionized, distilled water).  Dissolve
       cautiously reacting is vigorous) by adding dropwise 10.0 ml
       (1+1) hydrochloric acid and dilute to 100 mL in a volumetric
       flask with deionized, distilled water.  Store the solution in
       a screwcap Teflon FEP storage bottle (Sect. 6.2.3).

7.6.7  Chromium  solution, stock  (1 ml = 1000 p,g Cr) - Dissolve
       0.1923 g  chromium trioxide (CrO,) in deionized,  distilled
       water.  When solution is complete, acidify  with 1 ml cone.
       nitric acid and dilute  to  100 ml in a volumetric flask with
       deionized, distilled water.  Store the solution in  a screwcap
       Teflon FEP storage bottle  (Sect. 6.2.3).

7.6.8  Copper solution, stock  (1 ml =  1000 p.g Cu)  -  Pickle copper
       metal in  (1+9) nitric acid to an exact weight of 0.100 g.
       Dissolve  in 2 mL cone,  nitric acid.  Dilute to 100 ml in a
       volumetric flask with deionized, distilled water.   Store the
       solution  in a  screwcap  Teflon FEP  storage bottle
       (Sect. 6.2.3).

7.6.9  Iron solution, stock  (1 ml = 1000  p.g  Fe) -  Pickle  iron metal
       in  (1+1)  hydrochloric acid to an exact weight of 0.100 g.
       Dissolve  in 10 ml  (1+1) hydrochloric acid.  Dilute  to 100 ml
       in  a volumetric  flask with deionized, distilled  water
       (Sect. 7.1).   Store the solution  in a screwcap Teflon FEP
       storage bottle  (Sect. 6.2.3).
                            187

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 7.6.10 Lead solution, stock (1 ml = 1000 ^g Pb) - Dissolve 0.1613 g
        lead nitrate [Pb(N03)2]  in  a minimum  amount of  (1+1) nitric
        acid.  Add 5 ml cone, nitric acid.  Dilute to 100 ml in a
        volumetric flask with deionized, distilled water.  Store the
        solution in screwcap Teflon FEP storage bottle (Sect.  6.2.3).

 7.6.11 Magnesium solution, stock (1 ml = 1000 /zg Mg) - Dissolve
        0.1658 g magnesium oxide (MgO in 10 mL (1+1)  nitric acid,
        heating to effect solution.  Cool and dilute  to 100 ml in a
        volumetric flask with deionized, distilled water.  Store the
        solution in a screwcap Teflon FEP storage bottle
        (Sect.  6.2.3).

 7.6.12 Nickel  solution,  stock (1 mL = 1000 p.g Ni) -  Dissolve
        0.100 g nickel  metal  in 5 mL hot cone,  nitric acid.  Cool and
        dilute  to 100 mL  in a volumetric flask with deionized,
        distilled water.   Store the solution  in a screwcap Teflon FEP
        storage bottle  (Sect.  6.2.3).

 7.6.13 Phosphorus  solution,  stock (1  mL = 1000 ng P) - Dissolve
        0.3745  g ammonium phosphate, monobasic  [(NH,)H,POJ (CASRN
        7722-76-1)  in deionized,  distilled water and  dilute to  100 mL
        in  a volumetric flask.   Store  the solution  in a  screwcap
        Teflon  FEP  storage bottle (Sect.  6.2.3).

 7.6.14 Potassium solution, stock (1 mL  = 1000  jug K)  -  Dissolve
        0.1907  g potassium chloride  (KC1)  previously  dried at 110°C
        for 3 h,  in deionized,  distilled  water,  add 2 mL  (1+1)
        hydrochloric  acid  and dilute to  100 mL  in a volumetric  flask.
        Store the solution  in a  screwcap  Teflon  FEP storage bottle
        (Sect.  6.2.3).

 7.6.15  Selenium solution,  stock  (1 mL =  1000 ng Se)  - Dissolve
        0.1414  g  selenium dioxide  (Se02) in deionized, distilled
        water and dilute to 100 mL in a volumetric flask.   Store  the
        solution  in a screwcap Teflon FEP  storage bottle
        (Sect.  6.2.3).

 7.6.16  Sodium  solution, stock (1 mL = 1000 ng  Na) -  Dissolve
        0.2542  g  sodium chloride  (NaCl) in deionized,  distilled
       water.  Add 1.0 mL cone, nitric acid and dilute to  100 mL in
        a volumetric flask with deionized, distilled water.  Store
       the solution in a screwcap Teflon FEP storage  bottle
        (Sect. 6.2.3).

7.6.17 Thallium solution, stock (1 mL = 1000 p.g Tl)  - Dissolve
       0.1303 g thallous  nitrate (T1N03)  in deionized,  distilled
       water.  Add 1.0 mL cone, nitric acid and dilute to 100 mL in
       a volumetric flask with deionized, distilled water.  Store
       the solution in a  screwcap Teflon FEP  storage  bottle
       (Sect. 6.2.3).
                           188

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     7.6.18 Zinc solution,  stock (1 ml = 1000 M9 Zn) - Pickle zinc metal
            in (1+9) nitric acid to an exact weight of 0.100 g.   Dissolve
            in 5 ml cone, nitric acid.  Dilute to 100 ml in a volumetric
            flask with deionized, distilled water.   Store the solution in
            a screwcap Teflon FEP storage bottle (Sect. 6.2.3).

7.7  Prepare four 100 ml primary standard solutions (Sect. 3.11) by
     combining aliquots from the appropriate individual stock solutions
     (Sect. 7.6) in  volumetric flasks and diluting to the mark with
     deionized, distilled water.  For the wavelength and background
     correction positions recommended, prepare the primary standard
     solution using the following listed aliquot volumes of the
     individual stock standards.  Transfer the prepared primary standard
     solutions in screwcap Teflon FEP storage bottles (Sect. 6.2.3).

     7.7.1  Primary standard solution I (Volume = 100.0 ml)
             Analvte

               AT
               Ca
               Cd
               Cu
               Mg
               Sb
               Se
 Stock
Solution
             Aliquot
             Vol..  ml
  .6.1
  .6.6
  .6.5
  .6.8
 7.6.11
 7.6.2
 7.6.15
7.
7.
7,
7,
10.0
10.0
 2.0
 1.0
10.0
 5.0
 5.0
  Analyte
Cone..ug/ml

   100
   100
    20
    10
   100
    50
    50
     7.7.2 Primary standard solution II (Volume = 100.0 ml)
             Analvte

               As
               Cr
Stock
Solution

 7.6.3
 7.6.7
             Aliquot
             Vol.. ml

               10.0
                5.0
             Analyte
            Cone..  uq/mL

               100
                50
     7.7.3 Primary  standard solution  III  (Volume = 100.0 ml)


             Analvte
               Na
               Pb
               Tl
               Zn
 Stock
Solution
             Aliquot
             Vol.. ml
 7.6.16
 7.6.10
 7.6.17
 7.6.18
               10.0
               10.0
                5.0
                5.0
             Analyte
            Cone., uq/mL
               100
               100
                50
                50
                                 189

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     7.7.4 Primary standard solution IV (Volume = 100.0 ml)
             Analvte

               Be
               Fe
               K
               Ni
               P
  Stock
Solution

  7.6.4
  7.6.9
  7.6.14
  7.6.12
  7.6.13
 Aliquot
Vol.. ml

    2.0
   10.0
   20.0
    2.0
   10.0
  Analyte
Cone.. ttg/mL

     10
    100
    200
     20
    100
7.8  For calibrating the instrument, prepare four CAL solutions
     (Sect. 3.12), each in 100-mL volumetric flask by adding 10 ml TMAH
     (Sect. 7.4) and 5 ml of cone, nitric acid to 10 mL of each of the
     four primary standard solutions (Sect. 7.7) and dilute to the mark
     with deionized, distilled water.  Transfer the prepared calibration
     standards to screwcap Teflon FEP storage bottles (Sect. 6.2.3).

     7.8.1 CAL solution I (Volume = 100.0 mL)

             Analvte                   Cone.. ua/mL
               Al
               Ca
               Cd
               Cu
               Mg
               Sb
               Se

     7.8.2  CAL solution  II  (Volume

             Analvte

               As
               Cr
                 10.0
                 10.0
                  2.0
                  1.0
                 10.0
                  5.0
                  5.0

          100.0 mL)

            Cone.. uq/mL

                10.0
                  5.0
    7.8.3 CAL  solution  III  (Volume

            Analvte

               Na
               Pb
               Tl
               Zn
           100.0 mL)

             Cone.. ua/mL

                10.0
                10.0
                 5.0
                 5.0
                                190

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     7.8.4 CAL solution  IV (Volume = 100.0 ml)

             Analvte                    Cone..  ug/ml

               Be                           1.0
               Fe                          10.0
               K                           20.0
               Ni                           2.0
               P                           10.0

7.9  Prepare a calibration blank by diluting the combination solution
     of 10 ml TMAH (Sect. 7.4) and 5 ml cone, nitric acid to 100 ml in a
     volumetric flask with deionized, distilled water.  Store the
     calibration blank in a screwcap Teflon FEP storage bottle
     (Sect. 6.2.4).

7.10 Prepare, a laboratory performance check (LPC) stock solution in a
     100-mL volumetric flask by combining the following listed aliquot
     volumes of the individual stock standards  and diluting to the mark
     with deionized, distilled water.  Transfer the stock solution to a
     screwcap Teflon FEP storage bottle (Sect.  6.2.3).

                            Stock        Aliquot        Analyte
             Analvte       Solution      Vol..  ml      Cone.. jug/tnL
               Al           7.6.1           1.0            10.0
               As           7.6.3           1.0            10.0
               Be           7.6.4           2.0            10.0
               Ca           7.6.6           2.0            20.0
               Cd           7.6.5           1.0            10.0
               Cr           7.6.7           1.0            10.0
               Cu           7.6.8           1.0            10.0
               Fe           7.6.9           1.0            10.0
               K            7.6.14         10.0           100.0
               Mg           7.6.11          2.0            20.0
               Na           7.6.16          2.0            20.0
               Ni           7.6.12          1.0            10.0
               P            7.6.13         10.0           100.0
               Pb           7.6.10          1.0            10.0
               Sb           7.6.2           1.0            10.0
               Se           7.6.15          1.0            10.0
               Tl           7.6.17          1.0            10.0
               Zn           7.6.18          1.0            10.0

     7.10.1 At the time of calibration prepare  the LPC in a 100-mL
            volumetric flask by adding in the following order,  10 mL TMAH
            (Sect. 7.4) and 5 mL cone, nitric acid to 10 mL of the LPC
            stock solution (Sect. 7.10) and diluting to the mark with
            deionized, distilled water.  Transfer the LPC to a screwcap
            Teflon FEP storage bottle (Sect. 6.2.3).
                                 191

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                            Analvte
                              Al
                              As
                              Be
                              Ca
                              Cd
                              Cr
                              Cu
                              Fe
                              K
                              Mg
                              Na
                              Ni
                              P
                              Pb
                              Sb
                              Se
                              Tl
                              Zn
                          Calibration Check
                          Std. Cone.. uq/mL
                               10.0
                                2.0
                                2.0
                                1.0
                               10.0
                                1.0
                                1.0
7.11 Prepare the laboratory fortifying stock solution in a 200-mL
     volumetric flask by combining the following listed aliquot volumes
     of the individual stock solution and diluting to the mark with
     deionized, distilled water.  Transfer the laboratory fortifying
     stock solution to a screwcap Teflon FEP storage bottle
     (Sect. 6.2.3).
      Analvte

        AL
        As
        Be
        Cd
        Cr
        Cu
        Ni
        Pb
        Sb
        Se
        Tl
        Zn
  Stock
Solution
             Aliquot
            Vol.. ml
  7.6.1
  7.6.3
   .6.4
   .6.5
  7.6.7
  7.6.8
  7.6.12
   .6.10
   .6.2
   .6.15
  7.6.17
  7.6.18
7.
7.
7.
7.
7.
10.0
10.0
 1.0
 1.0
 2.0
 5.0
 5.0
 5.0
 5.0
10.0
 5.0
10.0
   Analyte
Cone.. uq/mL

     50
     50
      2.5
      5
     10
     25
     25
     25
     25
     50
     25
     50
7.12 Prepare an instrument wash acid solution by diluting 50 mL of cone.
     nitric acid to 1 L with deionized, distilled water.  Store in a
     convenient manner.  This solution is to be used to flush the
     solution uptake system and nebulizer between standards and samples.
                                 192

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8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  Fish samples are collected using a variety of equipment, methods
          and techniques such as trot lines, trawls, seines, dredges, nets,
          ichthyocides and electrofishing.  The technique used must be free
          from contamination by metals.  For example, permanganate may be
          used to detoxify Rotenone but should not come in contact with the
          fish to be analyzed.6

     8.2  Appropriate individual tissue samples should be taken soon after
          collection of the fish and must be taken prior to freezing.   If
          dissection of the tissue cannot be performed immediately after
          collection, each fish should be placed in a plastic bag
          (Sect. 6.1.5), sealed and placed on ice or refrigerated at
          approximately 4°C.

     8.3  Prior to dissection, the fish should be rinsed with metal-free
          water and blotted dry.  Dissection should be performed within 24 h
          of collection.  Each individual fillet sample should also be rinsed
          with metal-free water, blotted dry, placed in a preweighed,
          labeled polysulfone centrifuge tube (Sect. 6.2.2) and frozen at
          <-20°C (dry ice).
     8.4  Skinless fillet samples of approximately 1-2 g (1 cm x 0.5 cm x 2
          cm) should be cut from the fish using a special implement (Sect.
          4.1) and handled with plastic forceps (Sect. 6.1.2).8'9

     8.5  A maximum holding time for frozen samples has not been determined.

9.   CALIBRATION AND STANDARDIZATION

     9.1  Specific wavelengths and background correction locations given in
          Table 1 and instrument operating conditions given in Table 2
          should be used whenever possible.  However, because of the
          difference among various makes and models of spectrometers, the
          analyst should follow the instrument manufacturer's instructions
          in adapting the instrument's operation to approximate the
          recommended operating conditions.  Other wavelengths and
          background correction locations may be substituted if they can
          provide the needed sensitivity and are corrected for spectral
          interference.

     9.2  Allow the instrument to become thermally stable before beginning.
          This usually requires at least 30 min of operation prior to
          calibration.

     9.3  Optically profile the instrument and adjust the plasma to a
          previously established condition by regulating the argon flow rate
          through the nebulizer while monitoring the intensity ratio of
          selected atom/ion wavelengths [e.g., Cu (I) 324.75 nm/Mn (II) 257.61
          nm].


                                      193

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9.4
9.5
          Calibrate  the  instrument  according to the  instrument manufacturer's
          instructions using the prepared calibration blank  (Sect. 7.9) and
          CAL  solutions  (Sect.  7.8).

          The  following  operational steps should be  used for both CAL
          solutions  and  samples.
     9.5.1
                                                                     to
9.6
                 Using a peristalic pump introduce the standard or sample
                 nebulizer at a uniform rate  (e.g., 1.2 mL/min."1).

          9.5.2  To allow equilibrium to be reached in the plasma, aspirate
                 the standard or sample solution for 30 sec after
                 reaching the plasma before beginning integration of the
                 background corrected signal.

          9.5.3  Use the average value of four 4 sec background
                 corrected integration periods as the atomic emission signal
                 to be correlated to analyte concentration.

          9.5.4  Between each standard or sample, flush the nebulizer and
                 solution uptake system with the wash acid solution
                 (Sect. 7.12) for 60 sec or for the required period of time to
                 ensure that analyte memory effects are not occurring.

          Analyze the LPC solution (Sect. 7.10.1) and calibration blank
          (Sect. 7.9) immediately following calibration,  at the end of the
          analyses and periodically throughout the sample run.  The analyzed
          value of the LPC solution should be within an interval of 95% to
          105% of the expected value.   If the value is outside the interval,
          the instrument should be recalibrated and all  samples following the
          last acceptable LPC solution should be reanalyzed.

10.   QUALITY CONTROL

     10.1  Each laboratory using this  method is required  to operate a formal
           quality control  (QC)  program.   The minimum requirements of this
           program consist of an initial  demonstration of laboratory
           capability and the analysis of reagent blanks,  fortified blanks and
           samples as a continuing check  on performance.   The  laboratory is
           required to maintain  performance records that  define the quality of
           data thus generated.

     10.2  INITIAL DEMONSTRATION OF PERFORMANCE

           10.2.1   Initial  demonstration of performance  is used to
                    characterized  instrument and  laboratory performance,
                    (method  detection  limits and  quality  control  verification)
                    for analyses conducted  by this  method.

           10.2.2   When  beginning  the  use  of this  method  and  on a quarterly
                    basis, verify  acceptable laboratory performance with  the
                    preparation  and analyses of a quality  control  sample  (QCS)

                                     194

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               (Sect.  3.13).  The QCS  is carried through the entire
               analytical  operation of the method.   If the determined
               concentrations are not  within  ± 5%  stated values  of
               1 mg/L,  laboratory performance is unacceptable.   The
               source  of the problem should be identified and corrected
               before  continuing the analyses.

      10.2.3    Method  detection limit  (MDL) (Sect.  3.2) in M9/9  must be
               determined  for each of  the following analytes:  Al, As,
               Be,  Cd,  Cr,  Cu, Ni, Pb, Sb, Se,  Tl,  and Zn.   Except for
               As,  Cu  and  Zn, the MDLs for all  analytes must be
               determined  in the fish  tissue  matrix.  Because of
               background  concentrations in fish tissue, MDLs for As, Cu
               and  Zn  should be determined by fortifying and analyzing
               the  LRB (Sect. 3.5) matrix.  The MDL determinations should
               be made using seven replicate  samples prepared as
               described in the procedure  (Sect. 11.).  The  concentration
               of the  fortified analyte  in the sample should be
               approximately three times the  estimated detection limit.
               The  determined MDL values tested in  Table 1 can be used as
               a guide. (Actual solution concentration in jug/mL  are  10%
               of the  listed values).  Appropriate  dilutions of  the
               laboratory  fortifying stock solution (Sect. 7.11) may be
               used to determine MDL.

               Calculate the MDL as  follows:

               MDL  = (t) x (S)

               where,  t =  Student's  t  value for a  99% confidence
                          level and  a  standard deviation estimate
                          with  n-1 degrees of freedom [t = 3.14
                          for  seven  replicates].

                      S =  standard deviation  of the replicate  analyses.

               MDLs should be  determined yearly or whenever  there is a
               significant change  in background or instrument  response.

10.3  ASSESSING LABORATORY PERFORMANCE -  REAGENT AND FORTIFIED BLANKS

      10.3.1    A laboratory .reagent  blank  (LRB) (Sect. 3.5)  is to be
               analyzed with  each  group  of samples.  LRB data  are used to
               assess  contamination  from the  laboratory environment  and
               to  characterize spectral  background from reagents used in
               sample  processing.   Prepare the LRB by transferring 1.0 mL
               TMAH (Sect. 7.4) to  a clean preweighed, labeled 30-mL
               polysulfone Oak Ridge type  centrifuge tube  (Sect. 6.2.3).
               Carry the blank through the entire  procedure  (Sect.  11) as
               a 1.0 g sample  ending with  a  final  solution volume of
               10  mL.   If  the  value  for one  or more of the following


                                195

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                metals:  Al,  As,  Be,  Cd,  Cr,  Cu,  Ni,  Pb,  Sb,  Se, Tl,  and  Zn
                exceeds  its  determined MDL or  established  control  limits,
                then  laboratory  or reagent contamination should be
                suspected  and  attention  should be given  to the cleaning
                procedure  and  the purity of  the  reagents should be
                verified.  The source of contamination should be corrected
                before completing additional analyses.

       10.3.2    A field  reagent  blank (FRB)  (Sect. 3.6)  that accompanies
                each  group of  samples is  to  be analyzed  in the same  manner
                as the LRB.  Its purpose  is  to monitor sample collection
                and storage  condition.   Criteria for rejection of analyses
                data  based on  FRB data have  not  been determined.

       10.3.3    A laboratory fortified blank (LFB) (Sect.  3.8) is to be
                analyzed with  each group  of  samples.  The  LFB should
                contain the  following metals:  Al, As, Be, Cd, Cr, Cu, Ni,
                Pb, Sb, Se,  Tl, and Zn.   To  prepare the  LFB, pi pet 0.1 mL
                of the laboratory fortifying stock solution  (Sect. 7.11)
                into  a clean preweighed,  labeled 30-mL polysulfone Oak
                Ridge type centrifuge tube (Sect. 6.2.2).  Add 1 mL of
                TMAH  (Sect.  7.4) and carry the LFB through the entire
                procedure (Sect. 11) as a sample ending with a final
                volume of 10 mL.  The analyzed values should be within ±
                2 standard deviations of  an established mean value
                determined from seven prior replicate analyses.  (Data in
                Table 3 may  be used as a guide until  a sufficient number
                of replicates have been determined.)   If an analyzed value
                is greater than ± 2 standard deviations, it  is outside
               the warning limits.   If it is greater than ± 3 standard
               deviations, the analysis  is judged to be out of control.
               When this is the case,  take appropriate steps to identify
               and resolve the problems before continuing with the
               analyses.

10.4  ASSESSING ANALYTE RECOVERY -  LABORATORY FORTIFIED SAMPLE MATRIX

      10.4.1   To demonstrate  analyte  recovery from  the tissue matrix
               prepare and analyze  a laboratory  fortified  matrix sample
                (LFM)  (Sect.  3.9) for each type of tissue under analysis.
               Select one  fish from  each group of <  20 samples and at the
               time of dissection collect two  adjacent fillet  or tissue
               aliquots  of nearly equal  size (1  g).   To  one  of the
               aliquots  add  0.1  mL of  the laboratory fortifying  stock
               solution  (Sect. 7.11).   Carry both  aliquots through the
               entire procedure  (Sect.  11).
           ••
      10.4.2   Calculate the percent recovery  for  each  analyte,  corrected
               for  background  concentrations measured  in the unfortified
               aliquot,  and  compare  theses values  to  the control  limits
               established  in  Sect.  10.3.3 for the analyses  of  LFBs.
                                196

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                    Percent recovery may be calculated in units appropriate to
                    the matrix,  using the following equation:

                         R = (CF  -  C)  X  100
                         where,  R  = percent recovery.
                                CF  = fortified  sample concentration
                                C  = sample background  concentration
                                F  = concentration equivalent of analyte added
                                    to sample

           10.4.3   If the recovery of any analyte in  the LFM falls  outside
                    the designated  range and the laboratory performance for
                    that analyte is shown to be in control  (Sect. 10.3), the
                    recovery problem encountered with  the fortified  sample is
                    judged to be matrix related, not system related.  See
                    Sect. 13.4 and  Table 5 for typical  recovery data.
11.   PROCEDURE
     11.1  At the start of sample processing, remove the cap from the
           preweighed, labeled centrifuge tube (Sect. 6.2.2) containing the
           sample and reweigh the tube to determine the weight of the tissue
           by difference.  This can be done using the analytical balance
           (Sect. 6.3.5).  Wipe the outside of the centrifuge tube with a
           Kimwipe or suitable  paper tissue and place the tube horizontally
           on the pan.  The weight of the tissue should be between 1 and 2 g
           and expressed to the nearest 10 mg.  Record the tissue weight.

     11.2  Using a 2-mL graduated pipet or an air displacement pipetter
           (Sect. 6.3.1), add a volume of 25% tetramethylammonium hydroxide
           (TMAH) (Sect. 7.4) equal to the weight of the tissue (1 ml TMAH =
           1 g tissue).  The aliquot of TMAH should be to the nearest tenth of
           a milliliter equal to the tissue weight (e.g., 1.6 ml of TMAH for
           1.62 g of tissue).  With the TMAH added, replace and tighten the
           cap securely.  (This will minimize the odor caused in heating the
           sample mixture.)  Place the sample in an open rack for adequate
           heating and place the rack in a drying oven preheated to 65°C ±
           5°C and warm the  sample for 1 h.

     11.3  After an hour of heating, remove the sample from the oven,
           retighten the cap if loose, and mix the sample for a few seconds
           using a vortex mixer (Sect. 6.3.6) set at medium power setting.
           Return the sample to the drying oven and heat for an additional
           hour.

     11.4  After the second hour of heating, again vortex mix the sample and
           allow the capped sample to stand overnight at room temperature.
                                      197

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 11.5
11.6
11.7
11.8
 The following morning,  acidify the sample  with  cone,  nitric  acid
 (Sect.  7.2)  to between  4% and 5% (v/v)  acid.  The  volume  of  nitric
 acid added to each sample is  based on the  final  volume  of sample.
 The final  sample volume is calculated by multiplying  the  wet tissue
 weight  by  10.   Using a  1-mL graduated pipet or  an  air displacement
 pipetter (Sect.  6.3.1),  add the appropriate volume of nitric acid
 as  indicated in  the following table:
        Weight of
        Tissue, a
                         Final  Sample
                         Volume.  mL
0.80
1.05
1.25
1.45
1.65
1.85
2.05
- 1.04
- 1.24
- 1.44
- 1.64
- 1.84
- 2.04
- 2.24
                                8 to
                               10 to
                               12 to
                               14 to
                                10
                                12
                                14
                                16
                          16  to  18
                          18  to  20
                          20  to  22
   Volume of
Cone. HN03 Added,  ml

      0.4
      0.5
      0.6
      0.7
      0.8
      0.9
      1.0
After the  acid  addition, recap the tube and lightly vortex mix the
sample.  Place  the tube to the drying oven preheated to  100°C and
heat the sample for  an hour to solubilize the metals before
proceeding.  Note:   After the acid is added,' solids will fall out
of solution and a precipitate will form.  This  is normal and to be
expected.

After the  period of  solubilization, cool the tube to room
temperature.  Uncap  the tube and place the tube on the single pan
balance (Sect.  6.3.4) in a tared 100-mL Griffin beaker.  Adjust the
final volume of the  sample by adding deionized, distilled water
from a "squeeze" wash bottle (Sect. 6.2.4) while weighing the tube
to an appropriate weight to maintain the constant weight/volume
ratio of 1 g/10 ml.  The appropriate weight is calculated by
multiplying the wet  tissue weight by 10 and adding the product to
the recorded weight  of the empty tube.

After dilution  is completed, recap the tube and vortex mix the
sample.  After  mixing, centrifuge (Sect. 6.3.7) the sample at 2000
rpm. for 10 min.  After centrifuging, the sample may contain
floatable  solids as  a surface layer as well as the precipitate.
Also, some particles may adhere to the wall of the tube.  This
condition  is normal  and should not cause concern unless the
analysis solution actually contains suspended material. The sample
is now ready for analysis.   Analyze the sample within 24 h of
preparation (Sect. See 4.2).

Aspirate the sample  into the ICP using the same operating
conditions used in calibration (Sect. 9) while making certain the
precipitate is  not disturbed and inadvertently aspirated.  If the
surface of the  analysis solution is partially covered with
floatable solids,  proceed by removing the tip of the aspiration
tube from the wash solution (Sect.  7.12) and allow an air bubble
                                198

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           segment to form in the sample uptake line.   Reverse the pump flow
           and,  while back pumping the air bubble,  insert the aspiration tube
           past  the floatable solids into the sample solution.  Change the
           pump  flow back to uptake direction and aspirate the sample.

12.   CALCULATIONS

     12.1  If dilutions are performed, the appropriate factor must be
           applied to sample values.

     12.2  Data  read from the instrument in /zg/mL should be rounded to the
           thousandth place.

     12.3  Subtract the LFB where appropriate (Sect. 4.4).

     12.4  To express the data in concentrations of jug/9 wet  tissue weight
           multiply the rounded net ng/ml data by a factor of 10.

     12.5  Report jug/g wet  tissue weight data up to three significant
           figures.

     12.6  Do not report data below the determined MDL.

13.  PRECISION AND ACCURACY

     13.1  The precision and recovery data presented in this  method are single
           laboratory verification data only.  The data were  collected
           utilizing the recommended  instrument conditions described  in the
           method.

     13.2  The precision and recovery data presented in Table 3 are for the
           LFB concentrations recommended in this method.  The data can be
           used  as a guide  for quality control limits  (Sect.  10.3) until the
           time  the method  user establishes actual limits.

     13.3  The comparative  data for the four types of  fish fillets (bluegill,
           catfish,  salmon,  and tuna) presented  in Table 4 are for
           verification of  version  2.0 of this method.   In addition to version
           2.0,  data are  included  for the former version 1.3   of this method,
           which incorporated the  use of  50% hydrogen  peroxide and a  vigorous
           acid  digestion procedure that  utilizes nitric acid and hydrogen
          . peroxide  with  the digestate  finally being diluted  in 5% (v/v)
           hydrochloric acid.  The  analytes listed  are those  naturally
           occurring elements in  fish tissue plus Ni found in the salmon  and
           the Cd and  Se  found in  the tuna.  The purpose of  the comparison  is
           to demonstrate the effectiveness and  usefulness of the TMAH
           solubilization.   For  each  type of fish all  fillets were taken  from
           the  same  fish.   Except  as  noted  in  the table, Method 200.11 mean
           data  for  the analytes:  As, Cd, Cu,  Ni, Se and In  are from  the
           analyses  of four replicate fillets  while the mean  data for Ca, Fe,
           K, Mg, Na and  P  are from the  analyses of eight replicate fillets.
                                      199

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      The  acid  digestion mean  data  for  all  analytes  are  from the analyses
      of four replicate fillets.  The catfish,  salmon  and tuna data for
      version 2.0  of Method  200.11  were statistically  compared to version
      1.3  data  and the acid  digestion data.  The comparison was made
      using  a two  tail Student's t  test at  alpha level 0.05.  If a
      statistical  difference was determined, the data  were tested for
      practical difference by  determining the relative percent difference
      between the  two means.   If the relative percent  difference was 10%
      or less,  it  was concluded that there  is no practical difference
      between the  methods.   Listed  in Sect. 13.3.1 are the relative
      percent differences for  version 1.3 data  and in  Sect. 13.3.2 the
      relative  percent differences  for  the  acid digestion data for those
      analytes  where a statistical  difference was proven.  The large
      difference for the salmon data between version 2.0 and 1.3 cannot
      be explained.  At present, the differences are attributed to the
      individual fish used in  the comparison.  This was concluded from
      analyses  of  other fillet segments  from the same  fish that indicated
      good agreement between the two versions but gave extremely elevated
      concentrations for Cu  -  3 /jg/g, Fe -  18 /zg/g  and Zn - 8 /zg/g.

      13.3.1    RELATIVE PERCENT DIFFERENCES - VERSION  1.3
               ANALYTE

                 Fe
                 K
                 Mg
                 Na
                 P
                 P
                 Zn
FISH TISSUE

  Salmon
  Salmon
  Salmon
  Salmon
  Salmon
  Tuna
  Salmon
RELATIVE DIFFERENCE

         37%
         21%
         18%
         30%
         14%
          6%
         19%
      13.3.2   RELATIVE PERCENT DIFFERENCES - ACID DIGESTION
               ANALYTE

               As
               As
               Cu
               K
               Mg
               Na
               P
               P
FISH TISSUE

  Catfish
  Salmon
  Catfish
  Tuna
  Tuna
  Salmon
  Catfish
  Tuna
RELATIVE DIFFERENCE

         50%
         82%
         12%
         11%
         10%
         27%
          6%
         14%
13.4  The precision and recovery data for the four types of fish fillets
      (bluegill, catfish, salmon, and tuna) presented in Table 5 are from
      the analyses of four replicate LFMs taken from the same fish and
      fortified with the same concentrations as the LFB replicates listed
      in Table 3.  Sample concentration subtracted before calculation of
      percent recovered were mean values taken from Table 4.   Except for
                                200

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           Sb,  which shows consistently low recovery,  all  other analytes have
           recoveries that range from 90 to 112% with  an average of 101% and
           RSD  values that range from 0.7 to 10.7% with an average of 3.7%,
           only slightly higher than the LFB average of 3.1% calculated from
           Table 3 values.

     13.5  Table 6 lists the mean,  standard deviation, relative standard
           deviation, and percent recovery data from the analysis of four,
           0.25 g aliquots of dried NBS SRM 1566 Oyster Tissue.  Data from the
           analyses of reference material are included for support of the
           procedure.  Except for Cr and Fe, all recovery data are between 90
           and  110%.

14.   REFERENCES

   1.  Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.

   2.  Gross, S. B., and E. S. Parkinson, "Analyses of Metals in Human
       Tissues  Using Base (TMAH) Digests and Graphite Furnace Atomic
       Absorption Spectrophotometry," Atomic Absorption Newsletter. Vol. 13,
       No. 4, pp. 107-108, 1974.

   3.  Murthy,  L., E. E. Menden, P. M. Eller, and H. G. Petering, "Atomic
       Absorption Determination of Zinc, Copper, Cadmium and Lead in Tissues
       Solubilized by Aqueous Tetramethylammonium Hydroxide," Analytical
       Biochemistry. Vol. 53, pp. 365-372, 1973.

   4.  Versieck, J., and F. Barbier, "Sample Contamination as A Source of
       Error in Trace-Element Analysis of Biological Samples," Talanta.
       Vol. 29, pp. 973-984, 1982.

   5.  Annual Book of ASTM Standards, Volume 11.01, American Society for
       Testing and Materials, 1916 Race St., Philadelphia, Pennsylvania,
       19103.

   6.  Standard Methods for the Examination of Mater and Wastewater. 16th
       Edition, 1985.  Part 1006; "Fish: Sample Collection and Preservation."

   7.  Ney, J.  J., and M. G. Martin, "Influences of Prefreezing on Heavy
       Metal Concentrations in Bluegill Sunfish," Water Res.. Vol. 19, No. 7,
       pp. 905-907,  1985.

   8.  "The Pilot National Environmental Specimen Bank," NBS Special
       Publication 656, U. S. Department of Commerce, August, 1983.

   9.  Koirtyohann,  S. R., and H. C. Hopps, "Sample Selection, Collection,
       Preservation  and Storage for Data Bank on Trace  Elements  in Human
       Tissue," Federation Proceedings, Vol. 40, No. 8, June, 1981.

  10.  Method 200.11, "Determination of Metals  in Fish  Tissue by  Inductively
       Coupled  Plasma-Atomic Emission Spectrometry," Revision 1.3, April  1987.
       U.S.  Environmental Protection Agency, Office of  Research  and
       Development,  Environmental Monitoring and Support Laboratory,
       Cincinnati,  Ohio   45268.

                                      201

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          TABLE 1.  RECOMMENDED WAVELENGTHS WITH LOCATIONS
    FOR BACKGROUND CORRECTION AND METHOD DETECTION LIMITS  (MDL)
Analyte   Wavelength,
nm
  Location for
Bkgd. Correction
     MDL,  /xg/g
Wet Tissue Weight






(1)
(*)
AT
As
Be
Ca
Cd
Cr
Cu
Fe
K
Mg
Na
Ni
P
Pb
Sb
Se
Tl
Zn
Wavelength X 2
HDL determined
308.215
193.696
313.042
315.887
226.502
205.552
324.754
259.940
766.491
279.079
588.995
231.604
214.914
220.353
206.883
196.026
190.864
213.856
+ 0.061 nm
+ 0.061 nm
- 0.061 nm
+ 0.061 nm
+ 0.061 nm
X 2 - 0.030 nm
- 0.061 nm
+ 0.061 nm
- 0.061 nm
- 0.061 nm
+ 0.061 nm
X 2 - 0.030 nm
X 2 + 0.030 nm
+ 0.061 nm
+ 0.061 nm
- 0.061 nm
+ 0.061 nm
X 2 + 0.030 nm
indicates wavelength is read in
in LRB matrix.
0.3
0.4*
0.02
0.02
0.05
0.05*
0.08
0.2
0.2
0.6
0.5
0.07*
second order.
                                202

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TABLE 2.  INDUCTIVELY COUPLED PLASMA INSTRUMENT OPERATING CONDITIONS
     Forward  rf power
     Reflected  rf power
     Viewing  height above
        work  coil
     Argon supply
     Argon pressure
     Coolant  argon flow rate
     Aerosol  carrier argon
       flow rate
     Auxiliary (plasma)
       argon  flow rate
     Sample uptake rate
      controlled to
1100 watts
 < 5 watts

   16 mm
Liquid argon
  40 psi
  19 L/min

630 mL/min

300 mL/min

1.2 mL/min
                                  203

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        TABLE 3.    PRECISION AND RECOVERY OF DATA LABORATORY FORTIFIED BLANK
                                Concentration, /*g/g
Analyte
Al
As
Be
Cd
Cr
Cu
Ni
Pb
Sb
Se
Tl
Zn
Theo
Value
5.00
5.00
0.25
0.50
1.00
2.50
2.50
2.50
2.50
5.00
2.50
5.00
Analysis
Mean (1)
4.94
5.11
0.26
0.52
1.02
2.57
2.55
2.51
2.42
5.05
2.48
5.01
Std
Dev
0.14
0.13
0.01
0.01
0.04
0.07
0.08
0.09
0.22
0.16
0.09
0.13
RSD
2.8%
2.5%
3.7%
1.9%
3.9%
2.7%
3.1%
3.6%
9.1%
3.2%
3.6%
2.6%
Percent
Recovered
99%
102%
104%
104%
102%
103%
102%
100%
97%
101%
99%
100%
(1)  Data from seven replicate determinations
                                       204

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                        TABLE 4.   COMPARATIVE METHODS DATA
                      Concentration, M9/9 Wet Tissue Weight
Fish Tissue - Blueaill  Fillet

Analyte
As
Ca
Cu
Fe
K
Mg
Na
P
Zn
(1) Data from
Fish Tissue -


Analyte
As
Ca
Cu
Fe
K
Mg
Na
P
Zn
Method 200.11
Version 2.0 Version 1.3
Mean Std Dev Mean (1) Std Dev
1.08
141
0.18
1.57
4690
346
216
2640
4.74
duplicate
0.13
37
0.03
0.18
300
23
36
200
0.07
analyses
1.03
131
0.15
1.48
4870
370
247
2700
4.88
, standard
_«.
—
—
—
—
— —
—
—
— —
deviations
Acid Digestion
HNO,/H,0,
Mean (1) Std Dev
0.39
134
0.22
1.69
4140
340
235
2370
4.77
not provided










Catfish Fillet


Version
Mean
0.45
110
0.33
2.01
3400
244
460
1840
5.68

Method
2.0
Std Dev
0.10
5
0.09
0.30
240
16
17
90
0.58

200.11



Acid Digestion
Version 1.3
Mean Std Dev
0.47
111
0.35
1.95
3260
238
464
1750
6.02
0.14
15
0.10
0.23
370
38
19
200
1.07
HN03/H_2°2
Mean Sid Dev
0.20 0.
123
0.31 0.
2.38 0.
3640
230
467
1950
5.67 1.
06
2
01
53
70
7
6
30
68
                                         205

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                  TABLE 4.  COMPARATIVE METHODS DATA   (Continued)
                       Concentration, /zg/g Wet Tissue  Weight
 Fish Tissue - Salmon Fillet


Analyte
As
Ca
Cu
Fe
K
Mg
Na
Ni
P
Zn
Version
Mean
0.79
118
0.70
3.12
3160
233
653
0.09
2090
4.37
Method
2.0
Std Dev
0.03
14
0.05
0.55
180
10
64
0.04
100
0.40
200.11
Version
Mean
0.84
98
0.69
2.15
280
280
481
0.07*
2410
3.60
1.3
Std Dev
0.13
28
0.06
0.25
90
7
22
0.04
90
0.30
Acid
HP
Mean
0.41
114
0.57
3.16
3110
229
496
0.07
2000
3.72
Digestion
JO /H 0
ttd Dev
0.07
27
0.13
0.48
360
27
66
0.03
160
0.46
*Data below MDL, normally not reported - listed only for comparison

Fish Tissue - Tuna Fillet
Analyte
As
Ca
Cd
Cu
Fe
K
Mg
Na
P
Se
Zn
/•n M n ~
Method 200.11
Version 2.0 Version 1.3
Mean Std Dev Mean Std Dev
3.01
33.4
0.020
0.23
6.14
4640
384
328
3060
0.95
3.12
0.45
3.7
0.006
0.10
1.51
110
8
35
50
0.22
0.24
3.29
37.0
0.020
0.22
5.15
4530
373
360
2890
0.73
2.83
0.15
6.5
0.006
0.04
1.01
160
13
34
80
0.05
0.09
Acid Digestion
HN03/H202
Mean(l) SW Dev
2.83
37.8
0.025
0.11
7.33
4140
347
342
2670
N.DxO.8
2.90
0.39
7.8
0.003
0.04
1.08
120
10
J. V
39
90

0.23
                                       206

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TABLE 5.  PRECISION AND RECOVERY DATA
Concentration, M9/9 Wet Tissue Weight
Fish Tissue - Blueaill Fillet
Analyte
Al
As
Be
Cd
Cr
Cu
Ni
Pb
Sb
Se
Tl
Zn
*Data below
Fish Tissue
AnaTyte
Al
As
Be
Cd
Cr
Cu
Ni
Pb
Sb
Se
Tl
Zn
Sample Cone.
Cone. Added
1.08
-
0.18
-
0.54*
4.74
MDL, reported
5.00
5.00
0.25
0,50
1.00
2.50
2.50
2.50
2.50
5.00
2.50
5.00
for exp
Analysis
Mean
5.06
6.41
0.28
0.52
1.03
2.74
2.65
2.57
2.27
5.58
2.56
9.77
lanation of
Std
Dev
0.15
0.32
0.012
0.018
0.03
0.10
0.10
0.19
0.15
0.19
0.07
0.45
elevated If I
RSD
3.0%
5.0%
4.3%
3.5%
2.9%
3.6%
3.8%
7.4%
6.6%
3.4%
2.7%
4.6%
1
Percent
Recovery
101%
107%
112%
104%
103%
102%
106%
103%
91%
112%
102%
101%

-Catfish Fillet
Sampl e
Cone.
0.45
0.33

-
-
5.68
Cone.
Added
5.00
5.00
0.25
0.50
1.00
2.50
2.50
2.50
2.50
5.00
2.50
5.00
Analysis
Mean
4.94
5.50
0.26
0.49
0.98
2.85
2.42
2.43
2.09
4.60
2.43
11.0
Std
Dev
0.16
0.07
0.005
0.008
0.02
0.04
0.10
0.10
0.07
0.40
0.16
1.18
RSD
3.2%
1.3%
1.9%
1.6%
2.0%
1.4%
4.1%
4.1%
3.3%
8.7%,
6.6%
10.7%
Percent
Recovery
99%
101%
104%
98%
98%
101%
97%
97%
84%
92%
97%
106%
                   207

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TABLE 5.  PRECISION AND RECOVERY DATA  (Continued)
      Concentration, /zg/g Wet Tissue Weight
Fish Tissue - Salmon F^i^t

Analyte
Al
As
Be
Cd
Cr
Cu
Ni
Pb
Sb
Se
Tl
Zn
Fish Tissue

Analyte
Al
As
Be
Cd
Cr
Cu
Ni
Pb
Sb
Se
Tl
Zn

Sample
Cone.
0.79
0.70
0.09
4.37
- Tuna Fillet

Sample
Cone.
3.01
0.02
0.23
-
0.95
3.12

Cone.
Added
5.00
5.00
0.25
0.50
1.00
2.50
2.50
2.50
2.50
5.00
2.50
5.00


Cone.
Added
5.00
5.00
0.25
0.50
1.00
2.50
2.50
2.50
2.50
5.00
2.50
5.00

Analysis
Mean
4.67
5.59
0.25
0.47
0.93
3.20
2.41
2.38
2.01
5.05
2.36
8.85


Analysis
Mean
5.09
8.29
0.28
0.54
0.99
2.74
2.56
2.57
2.00
6.33
2.70
7.99

Std
Dev
0.23
0.13
0.002
0.015
0.03
0.12
0.11
0.09
0.15
0.28
0.90
0.62


Std
Dev
0.60
0.53
0.003
0.024
0.01
0.02
0.06
0.08
0.11
0.27
0.13
0.20

RSD
4.9%
2.3%
0.8%
3.2%
3.2%
3.8%
4.6%
3.8%
7.4%
5.5%
3.8%
7.0%


RSD
1.2%
6.4%
1.1%
4.4%
1.0%
0.7%
2.3%
3.1%
5.5%
4.3%
3.7%
2.5%

Percent
Recovery
93%
96%
100%
94%
93%
100%
93%
95%
80%
101%
94%
90%


Percent
Recovery
102%
106%
112%
104%
99%
100%
102%
103%
80%
108%
108%
97%
                     208

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              TABLE 6.  ANALYSES DATA - NBS SRM 1566 OYSTER TISSUE
                         Concentration, /Ltg/g Dry Weight
Analyte
As
Ca
Cd
Cr
Cu
Fe
K
Mg
Na
Ni
P
Pb
Se
Zn
Certified
Value
13.4 ± 1.9
1500 ± 200
3.5 ±0.4
0.69 ± 0.27
63.0 ± 3.5
195 ± 34
9690 ± 50
1280 ± 90
5100 ± 300
', 1.03 ± 0.19
8100*
0.48 ± 0.04
2.1 ± 0.5
852 ± 14
Analysis
Mean (1)
14.6
1560
3.39
N.DxO.02
63.0
128
9860
1270
4790
1.28
7360
N.DX0.8
N.D.<2.4
832
Std
Dev
0.2
80
0.05
-
1.5
16
50
30
110
0.41
180
-
- -
5
RSD
1.5%
5.1%
1.5%
-
2.4%
13%
0.5%
2.4%
2.3%
32%
2.4%
-
-
0.6%
Percent
Recovered
109%
104%
97%
-
100%
66%
102%
99%
94% .
124%
94%
'.';
-
98%
(1) N.D. - Not detected below MDL
*Phosphorus value not certified
                                        209

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                      METHOD 218.6
     DETERMINATION OF DISSOLVED HEXAVALENT CHROMIUM
IN DRINKING WATER, GROUNDWATER, AND INDUSTRIAL WASTEWATER
             EFFLUENTS BY ION CHROMATOGRAPHY
            Elizabeth  J.  Arar,  Stephen  E.  Long
              Technology Applications, Inc.
                           and

                      John D. Pfaff
                Inorganic Chemistry Branch
               Chemistry Research Division
                       Revision 3.2
                        April  1991
        ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
            OFFICE OF RESEARCH AND DEVELOPMENT
           U.S. ENVIRONMENTAL PROTECTION AGENCY
                  CINCINNATI, OHIO 45268
                            211

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                             METHOD 218.6

™uJERMINATION OF DISSOLVED HEXAVALENT CHROMIUM IN DRINKING WATER,
GROUNDWATER, AND  INDUSTRIAL WASTEWATER EFFLUENTS BY  ION CHROMATOGRAPHY
 SCOPE AND APPLICATION
 1.1
 1.2
 1.3
 1.4
           This method provides procedures for determination of dissolved
           nexavalent chromium in drinking water,  groundwater,  and industrial
           wastewater effluents.

           The method detection limits (MDL,  defined in  Sect. 3)  for the above
           matrices are listed in Table 1.   The MDL obtained by an individual
           laboratory for a specific matrix may differ from those listed
           depending on the nature of the sample and the instrumentation used.

           Samples  containing  high levels of anionic species such as sulphate
           and chloride may cause column  overload.   Samples containing  high
           levels of organics  or sulfides cause rapid reduction of soluble
           Cr(VI) to Cr(III).   Samples must be  stored at 4°C and  analyzed
           within 24 h  of collection.

           This  method  should  be used  by  analysts experienced in  the use  of ion
           chromatography and  the interpretation of ion  chromatograms.

2.   SUMMARY  OF METHOD

     2.1  An  aqueous sample is  filtered  through a  0.45-/im  filter and the
          filtrate  is adjusted  to a pH of  9 to 9.5 with  a  buffer solution   A
          measured  volume  of  the  sample  (50-250 /zL)  is  introduced  into the ion
          cnromatograph.   A guard column removes organics  from the  sample
          before the Cr(VI) as  CrO^'  is separated on an  anion exchange
          separator column.   Post-column derivatization  of the Cr(VI) with
          diphenylcarbazide is  followed by detection of the colored complex at
          530 nm.

3.   DEFINITIONS

     3.1  DISSOLVED - Material that will  pass through a  0.45 urn membrane
          filter.
3.2
3.3
          METHOD DETECTION LIMIT (MDL) - The minimum concentration of an
          analyte that can be identified,  measured and reported with 99%
          confidence that the analyte concentration is greater than zero-  it
          is determined from data produced by analyzing a sample in a qiven
          matrix containing analyte1.

          LINEAR DYNAMIC RANGE - The concentration range over which the
          analytical  working curve remains linear.
                                212

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   3 4   LABORATORY REAGENT BLANK  (LRB) - An aliquot of reagent water that is
         treated exactly like  a  sample including exposure to all glassware,
         equipment, solvents,  and  reagents that are used with.samples,   me
         LRB  is used  to determine  if the method analyte is present  in the
         laboratory environment, reagents, or  apparatus.

   3 5   STOCK STANDARD SOLUTION - A concentrated, certified standard
         solution  of  the method  analyte.  The  stock standard solution is used
         to prepare calibration  standards.

   3.6   CALIBRATION  STANDARD  (CAL) -  A  solution prepared  from  the  stock
         standard  and used to  calibrate  the  instrument response with respect
         to analyte concentration.

    3.7   LABORATORY  FORTIFIED  BLANK (LFB)  -  An aliquot of  reagent water to
         which a known quantity of method  analyte  is  added in  the laboratory.
         The LFB is  analyzed exactly  like  a  sample,  and its  purpose is  to
         determine whether the method is within accepted  control  limits.

    3.8  LABORATORY FORTIFIED SAMPLE MATRIX  (LFM)  - An aliquot of an
         environmental sample to which a known quantity of method analyte  is
         added in the laboratory.   The LFM is analyzed exactly like a sample,
         and its purpose is to determine whether the sample matrix
         contributes bias to the  analytical  result.  The background
         concentration of the analyte in the sample matrix must be determined
         in  a separate aliquot  and the measured value in the LFM corrected
         for the concentration  found.

    3.9  QUALITY CONTROL SAMPLE (QCS) - A solution containing a known
         concentration of analyte prepared by a laboratory other than the
         laboratory  performing  the analysis.  The sample is used to check
         laboratory  performance.

    3 10 LABORATORY  DUPLICATES  (LD) - Two aliquots of the same sample that
         are treated exactly  the  same throughout preparative and .analytical
         procedures.  Analyses  of laboratory  duplicates indicate precision
         associated  with  laboratory procedures.

    3  11 LABORATORY  PERFORMANCE CHECK STANDARDS (LPC)  - A solution of  the
         analyte  prepared in  the  laboratory  by making appropriate  dilutions
         of  the  stock standard  in reagent water.   The LPC is used  to evaluate
         the performance  of the instrument  system  within  a given calibration
          curve.

4.   INTERFERENCES

     4.1  Interferences which  affect  the accurate  determination of  Cr(VI)  may
          come from several  sources.

          4 1.1     Contamination - A trace  amount of Cr is  sometimes found in
                    reagent grade  salts.  Since a  concentrated buffer solution
                    is used in this method to adjust the pH of samples,

                                      213

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           4.1.2
           4.1.3
           4.1.4
                 reagent  blanks  should  be  analyzed  to  assess  for potential
                 Cr(VI) contamination.   Contamination  can  also come from
                 improperly  cleaned glassware or contact of caustic or
                 acidic reagents or samples with stainless steel or
                 pigmented material.

                 Oxidation of soluble Cr(III) to Cr(VI) can occur in an
                 alkaline medium in the  presence of oxidants  such as
                 Fe(III) and oxidized Mn or as a result of the aeration
                 that occurs in most extraction procedures2"5.

                 Reduction of Cr(VI) to Cr(III) can occur in the presence
                of reducing species in an acidic medium.  At a pH of 6 5
                or greater,  however,  HCrO" is converted to CrO/'which is
                less reactive than the HCr04'.                 4

                Overloading  of the analytical  column capacity with high
                concentrations of anionic species,  especially chloride and
                sulphate,  will  cause  a loss  of Cr(VI).  The  column
                specified in this  method can  handle samples  containing up
                to 5% sodium sulphate or 2%  sodium  chloride6.  Poor
                recoveries from  fortified  samples and  tailing peaks are
                typical manifestations  of  column overload.
5.   SAFETY

6.
             oH  c^°miUm  1S  ^OX1C  and  a  susPfcted  carcinogen  and  should
             5   Tth  aPP™Pnate precautions3'4.   Extreme  care should  be
     cd Wce", w?19hinf the salt  for preparation of  the  stock
     standard.   Each  laboratory is responsible for maintaining a  current
     rhpS6iSS flle-^ SS?A  Ration*  regarding the safe having of
     s^tv aiftfP ehlfied  ^  this., method.  A reference file of material
     safety data sheets should also be available to all personnel
     involved in the chemical analysis7-8.               p^onnei

APPARATUS AND EQUIPMENT

6.1  ION CHROMATOGRAPH
     6.1.1





     6.1.2

     6.1.3

     6.1.4

     6.1.5
                    Instrument equipped with a pump capable of withstanding a
                    minimum backpressure of 2000 psi  and of delivering a
                    constant flow in the range of 1-5 mL/min and containing no
                    metal  parts in the sample,  eluent or reagent flow path!

                    Helium gas supply (High purity,  99.995%).

                    Pressurized eluent container,  plastic,  1-  or 2-L  size.

                    Sample loops  of various  sizes  (50-2500L).

                    A pressurized  reagent delivery module with a mixing  tee
                    and beaded  mixing  coil.
                                     214

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     6.1.6      Guard  Column  -  A column  placed  before  the  separator  column
               and  containing  a sorbent capable  of removing  strongly
               absorbing organics  and particles  that  would otherwise
               damage the separator column  (Dionex lonPac NG1  or
               equivalent).

     6.1.7      Separator Column -  A column  packed with a  high  capacity
               anion  exchange  resin capable of resolving  Cr04 " from
               other  sample  constituents (Dionex lonPac AS7  or
               equivalent).

     6.1.8      A low-volume  flow-through cell, visible lamp  detector
               containing no metal parts in contact with  the eluent flow
               path.   Detection wavelength  is  at 530 nm.

     6.1.9      Recorder, integrator or  computer  for receiving analog  or
               digital signals for recording detector response (peak
               height or area) as  a function of  time.

6.2  LABWARE - All  reusable labware (glass, quartz, polyethylene, Teflon,
     etc.), including the sample containers, should be soaked overnight
     in laboratory grade detergent and  water,  rinsed with water, and
     soaked for 4 h in a mixture of dilute nitric and hydrochloric acid
     (1+2+9) followed by rinsing with tap water and ASTM type I water.

     NOTE:   Chromic acid must not be used for cleaning glassware.

     6.2.1     Glassware - Class A volumetric flasks and a graduated
               cylinder.

     6.2.2     Assorted Class A calibrated pipettes.

     6.2.3     10-mL male luer-lock disposable syringes.

     6.2.4     0.45-/wn  syringe filters.

     6.2.5     Storage  bottle - High density  polyproplene,  1-L capacity.

6.3  SAMPLE PROCESSING  EQUIPMENT

     6.3.1     Liquid sample  transport  containers  -  High density
               polypropylene,  125-mL capacity.

     6.3.2     Supply of dry  ice  or refrigerant  packing  and styrofoam
               shipment boxes.

     6.3.3     pH  meter - To  read pH range  0-14  with accuracy ± 0.03  pH
               units.

     6.3.4     0.45-/um  filter discs, 7.3-cm diameter (Gelman Aero  50A,
               Mfr.  No.  4262  or equivalent).


                                 215

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          6.3.5     Plastic syringe filtration unit (Baxter Scientific, Cat.
                    No. 1240 IN or equivalent).

7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1  REAGENTS - All chemicals are ACS grade unless otherwise indicated.

          7.1.1
          7.1.2

          7.1.3

          7.1.4

          7.1.5
Ammonium hydroxide, NH,OH, (sp.gr. 0.902),
(CASRN 1336-21-6).                      '

Ammonium sulphate, (NH4)2S04,  (CASRN 7783-20-2).

1,5-Diphenylcarbazide, (CASRN 140-22-7).

Methanol, HPLC grade.

Sulfuric acid, concentrated (sp.gr. 1.84).
     7.2   WATER -  For all  sample preparations  and dilutions,  ASTM Type I  water
          (ASTM D1193)  is  required.   Suitable  water may be obtained  by passing
          distilled  water  through a  mixed  bed  of anion  and cation exchange
          resins.                                                       3

     7.3   Cr(VI) STOCK  SOLUTION  - Dissolve 4.501  g of Na2CrO,'4H20 in ASTM
          Type  I water  and dilute to 1  L.   Transfer to  a polypropylene storaqe
          container.                                                         b

     7.4   LABORATORY  REAGENT  BLANK (LRB) - Aqueous LRBs  can be prepared by
          adjusting the pH of ASTM type  I  water  to 9-9.5 with the same volume
          of buffer as  is  used for samples.

     7.5   LABORATORY  FORTIFIED BLANK (LFB)  - To  an aliquot of LRB add  an
          aliquot of  stock standard  (Sect.  7.3)  to produce a final
          concentration of 100 /tg/L  of Cr(VI).  The  LFB  must be carried
          through the entire  sample  preparation and  analysis scheme.

    7.6   QUALITY CONTROL  SAMPLE  (QCS) - A  quality control sample must be
          obtained from an outside laboratory.  Dilute an aliquot according to
          instructions and analyze with samples.

    7.7   ELUENT - Dissolve 33 g of  ammonium sulphate in 500 mL of ASTM type I
         water and add 6.5 mL of ammonium hydroxide.  Dilute to  1 L with ASTM
         type I water.

    7.8  POST-COLUMN REAGENT - Dissolve 0.5 g of  1,5-diphenylcarbazide in 100
         mL of HPLC grade methanol.   Add to about 500 mL of ASTM type I water
         containing 28 mL of 98% sulfuric acid while stirring.   Dilute with
         ASTM type I water to 1  L in a volumetric flask.  Reagent is stable
         for four or five days but should be prepared only as needed
                                    216

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     7.9  BUFFER SOLUTION - Dissolve 33 g of ammonium sulphate in 75 ml of
          ASTM type I water and add 6.5 ml of ammonium hydroxide.  Dilute to
          100 ml with ASTM type I water.

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  Prior to sample collection, consideration should be given to the
          type of data required so that appropriate preservation and
          pretreatment steps can be taken.  Filtration and pH adjustment
          should be performed at the time of sample collection or as soon
          thereafter as practically possible.

     8.2  For determination of dissolved Cr(VI), the sample should be filtered
          through a 0.45-/«n filter.  Use a portion of the sample to rinse the
          syringe filtration unit and filter and then collect the required
          volume of filtrate.  Adjust the pH of the sample to 9-9.5 by adding
          dropwise a solution of the buffer, periodically checking the pH with
          the pH meter.  Approximately  10 ml of sample are sufficient for
          three 1C analyses.

     8.3  Ship and store the samples at 4°C.  Bring to ambient temperature
          prior to analysis.  Samples should be analyzed within  24 h of
          collection.

9.   CALIBRATION

     9.1  CALIBRATION  - Before samples  are  analyzed a calibration should be
          performed using  a minimum  of  three calibration solutions that
          bracket the  anticipated concentration range of the  samples.
          Calibration  standards  should  be prepared from the stock standard
           (Sect. 7.3)  by appropriate dilution with ASTM type  I water
           (Sect. 7.2)  in volumetric  flasks.  The solution should be adjusted
          to  pH 9-9.5  with the buffer solution  (Sect. 7.9) prior to final
          dilution.

          9.1.1      Establish  1C operating  conditions as indicated  in Table 2.
                    The  flow rate of the  eluent pump  is set at  1.5 mL/min and
                    the  pressure of  the reagent delivery module  adjusted  so
                    that the final  flow rate of the post column  reagent  (Sect.
                     7.8) from  the detector  is 2.0 mL/min.  This  requires
                    manual adjustment  and measurement of the  final  flow  using
                     a  graduated  cylinder and a  stop watch.  A warm  up  period
                     of approximately 30 min after the flow rate  has been
                     adjusted  is  recommended and the flow rate should  be
                     checked  prior to calibration and  sample  analysis.

           9.1.2     Injection  loop  size is  chosen  based on standard and  sample
                     concentrations  and  the  selected  attenuator  setting.   A
                     250-/iL loop  was  used to establish the method detection
                     limits in  Table 1.   A 50-jiL loop  is normally sufficient
                     for higher concentrations.  The  sample volume  used to load
                     the injection loop should be at  least  10  times  the loop

                                      217

-------
     9.1.3
9.2
                     size so that all tubing in contact with sample is
                     thoroughly flushed with new sample to prevent cross-
                     contamination.

                     A calibration curve of analyte response (peak height or
                     area) versus analyte concentration should be constructed.
                     IhL«oefflc1ent of correlation for the curve should be
                     0.999 or greater.

                      PE?™RMANCE - Check the performance  of the  instrument and
           it    "^^ation using data gathered  from analyses  of
           laboratory blanks,  calibration standards, and a QCS.
     9.2.1
     9.2.2
                     After the  calibration  has  been  established,  it  should  be
                     TI  ire   y  analyzi?2  a  QCS  (7'6>-   If the measured value
                     of  a  QCS exceeds ±  10% of  the established value, a second
                     analysis should be  performed.   If the value  still exceeds
                     the established value, the analysis  should be terminated
                     until  the  source of the  problem is identified and
                     corrected.

                     To  verify  that the  instrument is properly calibrated on a
                     continuing basis, run  a  LRB and a LPC after every ten
                     analyses.  The results of analyses of standards will
                     indicate whether the calibration remains valid.  If the
                    measured concentration of the analyte deviates from the
                    true concentration by more than ±5%,  the instrument must
                    be recalibrated and the previous ten  samples reanalyzed
                    The instrument response from the calibration check may be
                    used for recall oration purposes.

10.  QUALITY CQNTROI

     10.1 Each laboratory using this  method is  required to  operate a formal
          Troalll rnntr°J  (?C)  "W™:   The  minim requireLti  of this
          program consist  of an initial  demonstration  of  laboratory
                    hi3"?  the analy?1s of laboratory reagent  blanks,  and
                n   ?lank-  and  samples as  a c°ntinuing check  on performance.
            «ab?£atorVf reSu1£ed to  maintain  performance  records  that
          define the  quality of the data thus generated.

     10.2 INITIAL DEMONSTRATION OF  PERFORMANCE

                   The  initial demonstration of performance  is used  to
                   characterize  instrument performance (MDLs and linear
                   calibration range) for  analyses conducted by this method.

                   A MDL should  be established using reagent water fortified
                   at a concentration of two-five times the estimated
                   S^T 1i"1t\ T°.dejerm1ne the MDL value,  take seven
                   replicate aliquots of the fortified reagent water and
                   process through the entire analytical  method.   Perform all

                                    218
    10.2.1
    10.2.2

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                calculations  defined  in  the  method  and  report  the
                concentration values  in  the  appropriate units.   Calculate
                the MDL as  follows:

                MDL = (t) X (s)

                where:  t =  Student's  t value for a  99%  confidence  level
                and a standard deviation estimate with  n-1  degrees of
                freedom [t  =  3.143 for seven replicates].

                      s = standard deviation of the replicate  analyses.

      10.2.3    Linear dynamic range  - Linear dynamic ranges are governed
                by Beer's Law.  A set of at  least five  standards covering
                the estimated linear  range should be prepared  fresh from
                the stock solution and one analysis of each performed.   A
                log vs. log plot of peak height vs. analyte concentration
                having a slope between 0.98  and 1.02 will  indicate
                linearity (7).  The linear dynamic  range for this  method
                covered four orders of magnitude (1 /zg/L to 10,000 /*g/L)
                when peak height was  used.

10.3  ASSESSING LABORATORY  PERFORMANCE - REAGENT AND FORTIFIED BLANKS

      10.3.1    The laboratory must analyze at least one LRB (Sect. 7.4)
                with each set of samples.  Reagent  blank data are  used to
                assess contamination  from a laboratory environment.  If
                the Cr(VI)  value in the  reagent blank exceeds the
                determined  MDL, then  laboratory or reagent contamination
                should be suspected.   Any determined source of
                contamination should  be  corrected and the samples
                reanalyzed.

      10.3.2    The laboratory must analyze at least one LFB (Sect. 7.5)
                with each set of samples.  Calculate accuracy as percent
                recovery (Sect. 10.4.2).  If the recovery of Cr(VI) falls
                outside the control limits (Sect. 10.3.3), then the
                procedure is judged out  of control, and the source of the
                problem should be identified and resolved before
                continuing  the analysis.

     10.3.3     Until sufficient data become available (usually a minimum
                of 20 to 30 analyses), assess laboratory performance
                against recovery limits  of 90-110%.  When sufficient
                internal performance data becomes available, develop
                control limits from the percent mean recovery (x)  and the
                standard deviation (s) of the mean recovery.  These data
                are used to establish upper and lower control limits as
                follows:

                UPPER CONTROL LIMIT = x + 3s
                LOWER CONTROL LIMIT = x - 3s

                                  219

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10.4 ASSESSING ANALYTE RECOVERY - LABORATORY FORTIFIED SAMPLE MATRIX
     10.4.1
     10.4.2
                     The laboratory must add a known amount of Cr(VI)  to a
                     minimum of 10% of samples.   The concentration level can be
                     the same as that of the laboratory fortified blank
                     (Sect. 7.5).

                     Calculate the percent recovery for Cr(VI)  corrected for
                     background concentration measured in the unfortified
                     sample,  and compare this value to the control  limits
                     established in Sect.  10.3.3 for the analysis of LFBs.
                     Fortified recovery calculations are not required  if the
                     fortified concentration is  less than 10% of the sample
                     background concentration.   Percent recovery may be
                     calculated in units appropriate to the matrix,  using the
                     following equation:
               R =  CF -
                             C X 100
    10.4.3
                    where:

                    R = percent recovery.-
                    CF= fortified sample concentration.
                    C - sample background concentration.
                    F = concentration equivalent of Cr(VI) added to sample.

                    If the recovery of Cr(VI) falls outside control limits,
                    while the recovery obtained for the LFB was shown to be in
                    control (Sect. 10.3), the recovery problem encountered
                    with the fortified sample is judged to be matrix related,
                    not system related.  The result for Cr(VI) in the
                    unfortified sample must be labelled 'suspect matrix1.

     10.5 QUALITY CONTROL SAMPLE (QCS) - Each quarter, the laboratory should
          analyze one or more QCS (if available).   If criteria provided with
          the QCS are not met, corrective action should be taken and
          documented.

11.  PROCEDURE

     11.1 SAMPLE PREPARATION

          Filtered,  pH adjusted samples at 4°C should  be brought to  ambient
          temperature  prior to analysis.

     11.2 Initiate instrument  operating configuration  and  calibrate  (Sect.  9).

     11.3 Draw into  a  new,  unused  syringe (Sect. 6.2.3)  approximately  3  mL  of
          sample and attach  a  syringe  filter to  the syringe.   Discard  0.5 mL
          through the  filter and load  10X the sample loop  volume.  Samples

                                     220

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          having concentrations higher than the established linear dynamic
          range should be diluted into the calibration range.and reanalyzed.

12.  CALCULATIONS

     12.1 From the calibration curve the concentration of the sample can be
          determined.  Report values in ng/L.  Data should be corrected if any
          dilution of the sample occured.  Data should be corrected for any
          Cr(VI) contamination found in reagent blanks.

     12.2 The QC data obtained during sample analyses provide an indication of
          the quality of sample data and should be provided with sample
          results.

13.  PRECISION AND ACCURACY

     13.1 Instrument operating conditions used for single-laboratory testing
          of the method are summarized in Table 2.  Dissolved Cr(VI) MDLs
          (Sect. 10.2.2) are listed in Table 1.

     13.2 Data obtained from single-laboratory testing of the method are
          summarized in Table 3 for five water samples representing drinking
          water, deionized water, groundwater, treated municipal sewage
          wastewater, and treated electroplating wastewater.  Samples were
          fortified with 100 and 1000 fig/I of Or(VI) and recoveries determined
          (Sect. 10.4.2).

14.  REFERENCES

     1.   Glaser,*J.A., Foerst, D.L., McKee, 6.D., Quave, S.A. and Budde,
          W.L., "Trace Analyses for Wastewaters", Environ. Sci. and Technol..
          Vol.15, No.12, 1981, pp.1426-1435.

     2.   Bartlett, R. and James, B., "Behavior of Chromium in Soils: III.
          Oxidation", J. Environ. Qua!.. Vol.8, No.l, 1979, pp.31-35.

     3.   Zatka, V.J., "Speciation of Hexavalent Chromium in Welding Fumes
          Interference by Air Oxidation of Chromium", Am. Ind. Hvg. Assoc. J.,
          Vol.46, No.7, 1985, pp.327-331.

     4.   Pedersen, B., Thomsen, E. and Stern, R.M., "Some Problems in
          Sampling, Analysis and Evaluation  of Welding Fumes Containing
          Cr(VI)", Ann. Occup. Hvg.. Vol.31, No.3, 1987, pp. 325-338.

     5.   Messman, J.D., Churchwell, M.E., et.al.  Determination of Stable
          Valence States of Chromium in Aqueous and Solid Waste Matrices-
          Experimental Verification of Chemical Behavior.  EPA/600/S4-86/039,
          U.S.  Environmental Protection Agency, Cincinnati, Ohio,  1987, 112pp.

     6.   Dionex Technical Note No. 26, May  1990.
                                      221

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7.
8.
"Proposed OSHA Safety and Health Standards, Laboratories,"
Occupational Safety and Health Administration, Federal Register,
July 24, 1986.

"OSHA Safety and Health Standards, General Industry," (29 CFR 1910),
Occupational Safety and Health Administration, OSHA 2206, revised
January 1976.
9.   Johnson, D.C., Anal. Chim. Acta, Vol. 204, No.l, 1988.
                                222

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                 TABLE 1.  METHOD DETECTION LIMIT FOR CR(VI)
Matrix Type
Cone. Used to Compute MDL
         uq/L
MDL (a)
  ug/L
Reagent Water
Drinking Water
Ground Water
Primary Sewage
wastewater
Electroplating
wastewater
          1
          2
          2
          2
  0.4
  0.3
  0.3
  0.3

  0.3
(a) MDL concentrations are computed for final analysis concentration
    (Sect. 10.2).
                                      223

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                    TABLE 2.  ION CHROMATOGRAPH1C CONDITIONS
Columns:  Guard Column - Dionex lonPac NG1
          Separator Column - Dionex lonPac AS7
Eluent:  250 mM (NH,),SO,
         100 mM NH,OH
         Flow rate -1.5 mL/min

Post-Column Reagent:  2mM Diphenylcarbohydrazide
                      10% v/v CH,OH
                      1 N H2S04
                      Flow rate =0.5 mL/min

Detector:  Visible 530 nm

Retention Time:  3.8 min
                                      224

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              TABLE 3. SINGLE-LABORATORY PRECISION AND ACCURACY
Cr(VI)
Sample Type (/jg/L) (a)
Reagent Water

Drinking Water

Groundwater

Primary sewage
wastewater
effluent
Electroplating
wastewater
effluent
100
1000
100
1000
100
1000
100
1000
100
1000
Mean Recovery (%) RPD (b)
100
100
105
98
98
96
100
104
99
101
0.8
0.0
6.7
1.5
0.0
0.8
0.7
2.7
0.4
0.4
(a)   Sample fortified at this concentration level.
(b)   RPD - relative percent difference between duplicates.
                                     225

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                 METHOD 245.1

      DETERMINATION OF MERCURY  IN WATER
 BY COLD VAPOR ATOMIC ABSORPTION SPECTROMETRY
Edited by Larry B. Lobring and Billy B. Potter
          Inorganic Chemistry Branch
         Chemistry Research  Division
                 Revision 2.3
                  April 1991
  ENVIRONMENTAL  MONITORING  SYSTEMS  LABORATORY
      OFFICE OF RESEARCH AND DEVELOPMENT
     U.S. ENVIRONMENTAL PROTECTION AGENCY
            CINCINNATI,  OHIO   45268
                      227

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                             METHOD 245.1

                  DETERMINATION OF MERCURY IN WATER
             BY COLD VAPOR ATOMIC  ABSORPTION  SPECTROMETRY
 SCOPE AND APPLICATION

 1.1   This procedure1  measures total mercury  (organic + inorganic) in
      drinking,  surface,  ground,  sea,  brackish,  industrial  and  domestic
      wastewater.

 1.2   The range  of the method  is  0.2 to  10  p.g Hg/L.   The  range  may be
      extended above  or below  the normal  range by  increasing  or decreasing
      sample  size  or  by optimizing instrument sensitivity.

 SUMMARY  OF METHOD

 2.1   A 100-mL portion of a  water sample  is transferred to  a  BOD bottle
      (or an  equivalent flask  fitted with a ground glass  stopper).   It is
      digested in  diluted potassium permanganate-potasssium persulfate
      solutions  and oxidized for  2 h at 95°C. Mercury  in the digested
      water sample is  reduced with stannous chloride to elemental mercury
      and measured by  the conventional cold vapor atomic  absorption
      technique.

 DEFINITIONS
3.1
3.2
3.3
3.4
3.5
3.6
BIOCHEMICAL OXYGEN DEMAND  (BOD) BOTTLE - BOD bottle, 300 ± 2 mL with
a ground glass stopper or  an equivalent flask, fitted with a ground
glass stopper.

CALIBRATION BLANK - A volume of ASTM type II reagent water prepared
in the same manner (acidified) as the calibration standard.

CALIBRATION STANDARD (CAL) - A solution prepared from the mercury
stock standard solution which is used to calibrate the instrument
response with respect to analyte concentration.

INSTRUMENT DETECTION LIMIT (IDL) - The mercury concentration that
produces a signal equal to three times the standard deviation of the
blank signal.

LABORATORY FORTIFIED BLANK (LFB) - An aliquot of ASTM type II
reagent water to which known quantities of inorganic and/or organic
mercury are added in the laboratory.  The LFB is analyzed exactly
like a sample, and its purpose is to determine whether method
performance is within accepted control  limits.

LABORATORY FORTIFIED SAMPLE MATRIX (LFM)  - An aliquot of a water
sample to which known quantities of a calibration standard are added
                                 228

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          in  the  laboratory.   The  LFM  is  analyzed  exactly  like  a  sample,  and
          its purpose  is  to determine  whether  the  sample matrix contributes
          bias to the  analytical results.   The background  concentrations  of
          the analytes in the  sample matrix must be  determined  in a  separate
          aliquot and  the measured values  in the LFM corrected  for the
          concentrations  found.

     3.7  LABORATORY REAGENT  BLANK (LRB)  - An  aliquot of ASTM type II reagent
          water that is treated  exactly as a sample  including exposure  to all
          glassware, equipment,  and reagents used  in analyses.  The  LRB is
          used to determine  if method  analyte  or other interferences are
          present in the  laboratory environment, reagents  or apparatus.

     3.8  LINEAR  DYNAMIC  RANGE (LDR) - The concentration range  over  which the
          analytical working  curve remains linear.

     3.9  METHOD  DETECTION LIMIT (MDL) - The minimum concentration of mercury
          that can be  identified,  measured and reported with 99%  confidence
          that the analyte concentration is greater  than zero and determined
          from analysis of seven LFMs.

     3.10 QUALITY CONTROL SAMPLE (QCS) - A water  sample containing known
          concentration of mercury derived from externally prepared  test
          materials.  The QCS is obtained from a  source external  to  the
          laboratory and is used to check laboratory performance.

     3.11 WATER SAMPLE - For the purpose of this method,  a sample taken
          from one of  the following sources: drinking, surface, ground,
          sea, brackish,  industrial or domestic wastewater.

     3.12 STOCK STANDARD SOLUTION - A  concentrated mercury solution  containing
          prepared in  the laboratory using assayed mercuric chloride or stock
          standard solution purchased  from a reputable commercial source.

4.   INTERFERENCES

     4.1  Interferences have been reported for waters containing sulfide,
          chloride, copper and tellurium.  Organic compounds which have broad
          band UV absorbance (around 253.7 nm) are confirmed interferences.
          The concentration levels for interferants  are difficult to define.
          This suggests that quality control procedures (Sect.  10) must be
          strictly followed.

     4.2  Volatile materials which absorb at 253.7 nm will cause a positive
          interference.  In order to remove any interfering volatile
          materials, the dead air space in the BOD bottle  should be purged
          before addition of starinous  chloride solution.

5.   SAFETY

     5.1  The toxicity and carcinogenicity of each reagent used in this method
          has not been fully established.  Each chemical  should be regarded as

                                      229

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          a potential health hazard and exposure to these compounds should be
          minimized by good laboratory practices2.   Normal  accepted
          laboratory safety practices should be followed during reagent
          preparation and instrument operation.  Always wear safety glasses or
          full-face shield for eye protection when working with these
          reagents.  Each laboratory is responsible for maintaining a current
          safety plan, a current awareness file of OSHA regulations regarding
          the safe handling of the chemicals specified in this method *' 4.

     5.2  Mercury compounds are highly toxic if swallowed,  inhaled, or
          absorbed through the skin.  Analyses should be conducted in a
          laboratory exhaust hood.  The analyst should use chemical resistant
          gloves when handling concentrated mercury standards.

6.   APPARATUS AND EQUIPMENT

     6.1  ABSORPTION CELL - Standard spectrophotometer cells 10-cm long,
          having quartz windows may be used.  Suitable cells may be
          constructed from plexiglass tubing, 1-in. O.D.  by 4 1/2-in.  long.
          The ends are ground perpendicular to the longitudinal axis and
          quartz windows (1-in. diameter by 1/16-in. thickness) are cemented
          in place.  Gas inlet and outlet ports (also of plexiglass but 1/4-
          in.  O.D.) are attached approximately 1/2-in. from each end.   The
          cell is strapped to a burner for support and aligned in the light
          beam to give the maximum transmittance.

     6.2  AERATION TUBING - Inert mercury-free tubing is  used for passage  of
          mercury vapor from the sample bottle to  the absorption cell.   In
          some systems,  mercury vapor is recycled.   Straight glass tubing
          terminating in a coarse porous glass aspirator  is used for purging
          mercury released from the water sample in the BOD bottle.

          AIR PUMP - Any pump (pressure or vacuum  system) capable of passing
          air 1  L/min is used.   Regulated compressed air  can be used in an
          open one-pass  system.

          ATOMIC ABSORPTION SPECTROPHOTOMETER - Any atomic  absorption  unit
          having an open sample presentation area  in which  to mount the
          absorption cell  is suitable.   Instrument  settings recommended by the
          particular manufacturer should be followed.   Instruments designed
          specifically for mercury measurement using the  cold vapor technique
          are  commercially available and may be substituted for the atomic
          absorption spectrophotometer.

     6.5  BIOCHEMICAL OXYGEN DEMAND (BOD)  BOTTLE -  See Sect.  3.1.

     6.6  DRYING TUBE -  Tube (6-in.  x  3/4-in.  OD) containing  20 g  of magnesium
          perch!orate.   The  filled tube  is inserted (in-line)  between the  BOD
          bottle and the absorption tube.   In  place of the  magnesium
          perchlorate  drying tube,  a small  reading  lamp is  positioned to
          radiate heat  (about  10°C above ambient) on  the  absorption cell.
          Heat from the  lamp prevents water condensation  in  the cell.
6.3
6.4
                                     230

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     6.7   FLOWMETER - Capable of measuring an air flow of 1 L/min.

     6  8   MERCURY HOLLOW CATHODE LAMP - Single element hollow cathode lamp or
          electrodeless discharge lamp and associated power supply.

     6  9   RECORDER - Any multi-range variable speed recorder that is
          compatible with the UV detection system is suitable.

     6  10 WATER BATH - The water bath should have a covered top and capacity
          to sustain a water depth of 2-in. to 3-in. at 95°C ± 1°C.  The
          dimensions of the water bath should be large enough to accommodate
          BOD bottles containing CAL, LFB, LFM, LRB, QCS and water samples
          with the lid on.

7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1  Reagents may contain elemental  impurities which  bias analytical
          results.  All reagents should be assayed by the  chemical
          manufacturer for mercury and meet ACS specifications.  It  is
          recommended that the laboratory  analyst assay all reagents for
          mercury.

          7.1.1   Hydroxylamine Hydrochloride  (NHpOH'HCl),  (CASRN 5470-11-1)
                  may be  used in place of hydroxylamine sulfate  (Sect.  7.6);
                  assayed mercury level of compound  is not to exceed 0.05 ppm.

          7.1.2   Hydroxylamine Sulfate [(NH2OH)2'H2Sq4],  (CASRN 10039-54-0);
                  assayed mercury level of compound  is not to exceed 0.05 ppm.

          7.1.3   Mercuric Chloride  (HgCl2),  (CASRN 7487-94-7).

          7.1.4   Nitric  Acid (HN03), concentrated  (sp.gr.  1.41),  (CASRN  7697-
                   37-2);  assayed mercury  level  is  not to exceed  1  ppb.

          7.1.5    Potassium  Permanganate  (KMn04),  (CASRN 7722-64-7);
                   assayed mercury  level  is not to  exceed 0.05 ppm.

          7.1.6    Potassium  Persulfate (K2S208), (CASRN 7727-21-1); assayed
                   mercury level  is  not to exceed 0.05 ppm.

          7.1.7    Reagent Water,  ASTM type II5.

          7.1.8    Sodium Chloride (NaCl), (CASRN 7647-14-5);  assayed
                   mercury level  is not to exceed 0.05 ppm.

           7.1.9    Stannous Chloride (SnCl2-2H20), (CASRN 10025-69-1);
                   assayed mercury level is not to exceed 0.05 ppm.

           7.1.10  Stannous Sulfate, (SnSO,), (CASRN 7488-55-3);  assayed mercury
                   level  is not to exceed 0.05 ppm.
                                        231
                                                                                         ,~,

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           7.1.11
                   Sulfunc Acid (H?S04),  concentrated (sp.gr.  1.84),
                   (CASRN 7664-93-9); assayed mercury level is not to
                   exceed 1 ppb.
      7.2
           MERCURY CALIBRATION STANDARD - To each volumetric flask used for
           serial dilutions, acidify with (0.1 to 0.2% by volume) HNO,
           (Sect. 7.1.4).  Using mercury stock standard (Sect. 7.3), make
           serial dilutions to obtain a concentration of 0.1 0g Hg/mL.  This
           standard should be prepared just before analyses.

      7.3  MERCURY STOCK STANDARD - Dissolve in a 100-mL volumetric flask
           0.1354 g HgCl, (Sect.  7.1.3)  with 75 ml of reagent water (Sect.
           7.1.7).  Add 10 ml of cone. HN03  (Sect. 7.1.4)  and dilute to mark.
           Concentration is 1.0 mg Hg/mL.

      7.4  POTASSIUM PERMANGANATE SOLUTION - Dissolve 5 g of KMnO
           (Sect. 7.1.5) in 100 mL of reagent water (Sect. 7.1.7);

      7.5  POTASSIUM PERSULFATE SOLUTION - Dissolve 5 g of K,S,Oft (Sect. 7 1 6)
           in  100 mL of reagent water (Sect. 7.1.7).

      7.6  SODIUM CHLORIDE-HYDROXYLAMINE SULFATE SOLUTION - Dissolve 12 q of
           N!CJu(nuuV-, 7/c1'8)  and 12  g of  (NH2OH)2'H2S04 (Sect. 7.1.2) or  12 g
           of  NH2OH'HC1  (Sect. 7.1.1)  reagent water (Sect. 7.1.7) to 100 mL.

      7.7  STANNOUS  CHLORIDE SOLUTION -  Add  25  g of SnCl2'2H20 (Sect.  7.1 9) or
           25  g of SnS04 to  250 mL of 0.5 N  H2S04 (Sect. ^.8?.  This mixture is
           a suspension  and  should  be stirrecT continuously during  use.

     7.8   SULFURIC ACID,  0.5 N - Slowly add 14.0  mL  of cone.  H?SO,
           (Sect.  7.1.11)  dilute  to 1  L  with reagent  water (Sect.  7.1.7).

8-   SAMPLE COLLECTION. PRESERVATION AND STQRAGF
     8.1
          Because of the extreme sensitivity of the analytical  procedure  and
          the presence of mercury in a laboratory environment,  care must  be
          taken to avoid extraneous contamination.  Sampling devices,  sample
          containers and plastic items should be determined to  be free of
          mercury; the sample should not be exposed to any condition  in the
          laboratory that may result in contamination from airborne mercury
          n»Eor,V  A11  1tems used in san)Ple preparation should be soaked in 30%
          LJMf|  /v*-»**^**«1J'\— — -I .-. J	_ _ I  • i     ••     .
          7.1^7).
>                      7i>!\   j     	     r.—r^i »» • u.,  .JMISU i u i/c ouartcu 111
             3 (beet. 7.1.4) and rinsed three times in reagent water  (Sect.
     8.2
          The water sample should be preserved with HN03 (Sect.  7.1.4) to
          pH ^ 2.
9.   CALIBRATION AND STANDARDIZATION
     9.1
          Transfer 0.5,  1.0,  2.0,  5.0 and 10 mL aliquots of the 0.1 jug/mL CAL
          (Sect.  7.2)  to a series  of 300-mL BOD bottles.  Dilute standards to
                                      232

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          100 ml and process as described in Sect.  11.2.   These BOD bottles
          will contain 0.5 to 1.0 /zg of Hg and are used to calibrate the
          instrument.

     9.2  Construct a standard curve by plotting peak height or maximum
          response of the standards as obtained in  Sect.  11.7,  versus
          micrograms of mercury contained in the bottles.   The  standard curve
          should comply with Sect. 10.2.3.  Calibration using computer or
          calculator based regression curve fitting techniques  on
          concentration/response data is acceptable.

10.   QUALITY CONTROL

     10.1 Each laboratory using this method is required to operate a formal
          quality control (QC) program.  The minimum requirements of this
          program consist of an initial demonstration of laboratory capa-
          bility by analysis of laboratory reagent  blanks, fortified blanks
          and samples used for continuing check on  method performance.
          Commercially available water quality control  samples  are acceptable
          for routine laboratory use.  The laboratory is  required to maintain
          performance records that define the quality of the data generated.

     10.2 INITIAL DEMONSTRATION OF PERFORMANCE.

          10.2.1  The initial demonstration of performance is used to
                  characterize instrument performance (MDLs and linear
                  calibration ranges) for analyses  conducted by this method.

          10.2.2  A mercury MDL should be established using reagent water
                  (blank) fortified at a concentration  of two to five times
                  the estimated detection limit6.   To determine MDL values,
                  take seven replicate aliquots of  the  fortified reagent water
                  and process through the entire analytical method.  Perform
                  all calculations defined in the method  and report the
                  concentration values in the appropriate units.  Calculate
                  the MDL as follows:

                  MDL = (t) x (S)

                  where: t =  Student's t value for a 99% confidence level  and
                              a standard deviation  estimate with n-1 degrees
                              of freedom is, t = 3.14 for seven replicates.

                         S =  standard deviation of the replicate analyses.

                  A MDL should be determined every  six  months or whenever a
                  significant change in background  or instrument response is
                  expected (e.g., detector change).

          10.2.3  Linear calibration ranges - The upper limit of the linear
                  calibration range should be established for mercury by


                                      233

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             determining the signal responses from a minimum of three
             different concentration standards, one of which is close to
             the upper limit of the linear range.  Linear calibration
             ranges should be determined every six months or whenever a
             significant change in instrument response is observed.

10.3 ASSESSING LABORATORY PERFORMANCE - REAGENT AND FORTIFIED BLANKS

     10.3.1  The laboratory must analyze at least one LRB (Sect. 3.7)
             with each set of samples.  LRB data are used to assess
             contamination from the laboratory environment and to
             characterize spectral background from the reagents used in
             sample processing.  If a mercury value in a LRB exceeds its
             determined MDL, then laboratory or reagent contamination is
             suspect.  Any determined source of contamination should be
             eliminated and the samples reanalyzed.

     10.3.2  The laboratory must analyze at least one LFB (Sect. 3.5)
             with each batch of samples.  Calculate accuracy as percent
             recovery (Sect. 10.4.2).  If recovery of mercury falls
             outside control limits (Sect. 10.3.3), the method is judged
             out of control.  The source of the problem should be
             identified and resolved before continuing analyses.

     10.3.3  Until sufficient data (usually a minimum of 20 to 30
             analyses) become available, each laboratory should assess
             its performance against recovery limits of 85-115%.  When
             sufficient internal performance data become available,
             develop control limits from the percent mean recovery (x)
             and the standard deviation (S) of the mean recovery.  These
             data are used to establish upper and lower control limits as
             fol1ows:

                  UPPER CONTROL LIMIT = x + 3S
                  LOWER CONTROL LIMIT = x - 3S

             After each five to ten new recovery measurements,  new
             control limits should be calculated using only the most
             recent 20 to 30 data points.

10.4 ASSESSING ANALYTE RECOVERY - LABORATORY FORTIFIED SAMPLE MATRIX

     10.4.1  The laboratory must add a known amount of mercury to a
             minimum of 10% of samples or one sample per sample set,
             whichever is greater.   Select a water sample that is
             representative of the type of water sample being analyzed
             which has a low mercury background.   It is recommended that
             this sample be analyzed prior to fortification.   The
             fortification should be 20% to 50% higher than the analyzed
             value.   Over time,  samples from all  routine sample sources
             should be fortified.
                                234

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          10.4.2  Calculate the percent recovery,  corrected for background
                  concentrations measured in the unfortified sample,  and
                  compare these values to the control  limits established in
                  Sect.  10.3.3 for the analyses of LFBs.   A recovery
                  calculation is not required if the concentration of the
                  analyte added is less than 10% of the sample background
                  concentration.  Percent recovery may be calculated  in units
                  appropriate to the matrix, using the following equation:
                           _  Q
                               x 100
          10.4.3
11.   PROCEDURE
where, R  = percent recovery
       Cs = fortified sample concentration
       C  = sample background concentration
       s  = concentration equivalent of fortifier added to
            water sample.

If mercury recovery falls outside the designated range, and
the laboratory performance is shown to be in control
(Sect. 10.3), the recovery problem encountered with the
fortified water sample is judged to be matrix related, not
system related.  The result for mercury in the unfortified
sample must be labelled to inform the data user that the
results are suspect due to matrix effects.
     11.1 Transfer 100 ml of the water sample [or an aliquot diluted
          with reagent water (Sect.  7.1.7)  to 100 ml] into a BOD
          bottle.

     11.2 Add 5 ml of H2S04  (Sect. 7.1.11) and 2.5 ml of HN03
          (Sect. 7.1.4) to the sample.

     11.3 To each  bottle add 50 ml reagent  water (Sect.  7.1.7)  and 15 ml KMnOA
          solution (Sect. 7.4).  For sewage or industry  wastewaters,
          additional  KMn04 may be required.   Shake and add additional  portions
          of KMn04 solution,  if necessary, until the purple color persist for
          at least 15 min.  Add 8 ml of KpS208 solution (Sect. 7.5) to each
          bottle.   Mix thoroughly, cap and  cover the top of the BOD bottle
          with aluminum foil or other appropriate cover.   Heat  for 2 h in a
          water bath  at 95°C.

     11.4 Turn on  the spectrophotometer and circulating  pump.  Adjust the pump
          rate to  1  L/min.  Allow the spectrophotometer  and pump to stabilize.

     11.5 Cool the BOD bottles to room temperature and dilute in the following
          manner:

                                      235

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          11.5.1  To each BOD bottle containing the instrument calibration LFB
                  and LRB, add 50 ml of reagent water (Sect. 7.1.7).

          11.5.2  To each BOD bottle containing a water sample, QCS or LFM,
                  add 55 ml of reagent water (Sect. 7.1.7).

     11.6 To each BOD bottle, add 6 ml of NaCl-(NH2OH)2'H2S04 solution
          (Sect. 7.6) to reduce the excess permanganate.

     11.7 Treating each bottle individually:

          11.7.1  Placing the aspirator inside the BOD bottle and
                  above the liquid, purge the head space (20 to 30
                  sec) to remove possible gaseous interference.

          11.7.2  Add 5 ml of SnCl2 solution (Sect.  7.7)  and
                  immediately attach the bottle to the aeration
                  apparatus.

          11.7.3  The absorbance, as exhibited either on the
                  spectrophotometer or the recorder, will increase
                  and reach maximum within 30 sec.  As soon as the
                  recorder pen levels off, approximately 1 min, open
                  the bypass value (or optionally remove aspirator
                  from the BOD bottle if it is vented under the
                  hood) and continue aeration until  the absorbance
                  returns to its minimum value.

     11.8 Close the by-pass value, remove the aspirator from the BOD
          bottle and continue aeration.  Repeat (Sect. 11.7) until
          all BOD bottles have been aerated and recorded.

12.  CALCULATIONS

     12.1 Measure the peak height of the unknown from the chart and read the
          mercury value from the standard curve.

     12.2 Calculate the mercury concentration in the sample by the formula:
Ha/L =
0911,
       n
aliquot
                                                 1,000      \
                                                of aliquot)
     12.3 Report mercury concentrations as follows:  Below 0.2 /zg/L,
          < 0.2 /jg/L; between 1 and 10 /w}/L, one decimal;  above 10 #g/L,  whole
          numbers.

13.  PRECISION AND ACCURACY

     13.1 In a single laboratory (EMSL), using a Ohio River composite sample
          with a background mercury concentration of 0.35  Hg /jg/L and

                                      236

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          fortified with concentration of 1.0, 3.0, and 4.0 Hg /jg/L, the
          standard deviations were ± 0.14, ± 0.10 and ± 0.08 Hg fig/I,
          respectively.  Standard deviation at the 0.35 Hg /ig/L level was ±
          0.16 Hg /jg/L.  Percent recoveries at the three levels were 89, 87,
          and 87%, respectively.

     13.2 In a joint EPA/ASTM inter!aboratory study of the cold vapor
          technique for total mercury in water, increments of organic and
          inorganic mercury were added to natural waters.  Recoveries were
          determined by difference.  A statistical summary of this study is
          found in Table 1.

14.  REFERENCES

     1.   Kopp, J.F., Longbottom, M.C., and Lobring, L.B., " 'Cold Vapor1
          Method for Determining Mercury"; J. Am. Water Works Assoc.. Vol. 64,
          No. 1, January 1972.

     2.   "Safety in Academic Chemistry Laboratories", American Chemical
          Society Publication, Committee on Chemical Safety, 3rd Edition,
          1979.

     3.   "OSHA Safety and Health Standards, General Industry", (29CFR 1910),
          Occupational Safety and Health Administration, OSHA 2206, revised
          January 1976.

     4.   "Proposed OSHA Safety and Health Standards, Laboratories",
          Occupational Safety and Health Administration, Federal Register,
          July 24, 1986.

     5.   "Specification for Reagent Water", D1193, Annual Book of ASTM
          Standards. Vol. 11.01, 1990.

     6.   Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.
                                     237

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       TABLE 1.  INTERLABORATORY PRECISION AND ACCURACY DATA
                 FOR FLAHELESS ATONIC ABSORPTION
Number   True Values
of Labs    UQ/L
                     Mean Value
                      fla/L
                        Standard
                       Deviation
                        RSD       Mean
                         %     Accuracy as
                       	% Bias
76
80
82
77
82
79
79
78
0.21
0.27
0.51
0.60
3.4
4.1
8.8
9.6
                         0.349
                         0.414
                         0.674
                         0.709
                          .41
                          .81
                         8.77
                         9.10
3.
3.
              0.276
              0.279
              0.541
              0.390
49
12
69
              3.57
89
67
80
55
44
29
42
39
66
53
32
18
 0.34
-7.1
-0.4
-5.2
                                   238

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           O * BUBBLER
ABSORPTION
    CELL
    SAMPLE SOLUTION
    IN BOO BOTTLE
       SCRUBBER
0-4*"* CONTAINING
       A MERCURY
       ABSORBNO
       MEDIA
         Flgurt 1.  Apparatus for FlaaeUss Itercury Iteterainatlon
Because of the toxic nature of mercury vapor,  inhalation must be avoided.
Therefore, a bypass has been included in the system to either vent  the mercury
vapor into a exhaust hood or pass the vapor through some absorbing  media, such
as:   a) equal volumes of 0.1 N KMnO, and 10% H2S04
      b) 0.25% iodine in a 3X KI solution.
A specially treated charcoal that will absorb mercury vapor is also available
from Barnebey and Cheney, P.O. Box 2526, Columbus, OH  43216, Catalog No. 580-
13 or 580-22.
                                  239

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                            METHOD 245.3

DETERMINATION OF INORGANIC MERCURY (II) AND SELECTED OR6ANOMERCURIALS IN
DRINKING AND GROUND WATER BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
(HPLC) WITH ELECTROCHEMICAL DETECTION (ECD)
                     Otis Evans and Betty Jacobs
                      Inorganic Chemistry Branch
                     Chemistry Research Division
                             Revision 1.1
                              April  1991
              ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
                  OFFICE OF RESEARCH AND DEVELOPMENT
                 U.S. ENVIRONMENTAL PROTECTION AGENCY
                        CINCINNATI, OHIO  45268
                                  241

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                                  METHOD 245.3
      DETERMINATION OF INORGANIC MERCURY (II  AND SELECTED ORGANOMERCURIAL S IN
                                                                 HELS
      SCOPE AND APPLICATION


      lpl  ™™,meth°d -S aPP]ic?b?? to the determination of certain dissolved
           mercury species in drinking and ground water.

      1.2  The analytical range is approximately 2 /*g/L to 10 mg/L inorganic
           mercury (II) and organometallic mercury compounds.
 1.3
           The method detection limits (MDLs)  are 1.8 ng/i for mercury (II)
           1.9 /*g/L for methyl mercury, 1.7 jug/L for ethylmercury, and 0.8  '
           for phenyl mercury.
      1.4  This  method should be used by analysts  experienced  in  liquid
           chromatography with electrochemical  detection  (LCEC).

 2.    SUMMARY OF METHOD
 2.1
          This method  describes  a  procedure  for the  speciation of certain
          dissolved mercury  ionic  analytes in drinking and ground water
          Inorganic mercury  (II),  methyl mercury, ethylmercury, and
          phenylmercury are  determined by reversed-phase HPLC with reductive
          amperometric electrochemical detection1'6.  The mercury analytes are
          neural I°HP° *" ?lth ^captoethanol (2-ME) to form charge
          SI* i ??     *:  T?e  mercury complexes  are eluted with 60%  (w/w)
          methanol (isocratic elution conditions) buffered at pH 5 5   The

               1ll                                    at a f1ow rat^ °f 0.6
3.   DEFINITIONS
     3>1
3.2
           hp«rf     a!Id F52) - Two separate sat"Ples collected at
          the same time and placed under identical  circumstances and treated
          of FD yan5%nr-thr°U9h field andulab°^tory procedures.   Analyses
          of FD1 and FD2 give a measure of the precision associated  with
          sample collection,  preservation and storage,  as well  as with
          laboratory procedures.

          FIELD REAGENT BLANK (FRB)  - Reagent water placed in  a sample
          container in the laboratory and treated as a  sample  in all  respects
          including exposure  to sampling site conditions,  storage    respects'
          preservation and all  analytical  procedures.   The -purpose of the FRB
          r^Pnde-eThnVfifth°?  analytes  or  other interferences  are
          present  in the field  environment.
                                     242

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3 3  LABORATORY DUPLICATES  (LD1 and LD2) - Two sample aliquots taken in
     the analytical laboratory and analyzed separately with identical
     procedures.  Analyses  of LD1 and LD2 give a measure of the precision
     associated with laboratory procedures, but not with sample
     collection preservation, or storage procedures.

3.4  LABORATORY FORTIFIED BLANK (LFB) - An aliquot of reagent water  to
     which  known  quantities of the method analytes are added in the
     laboratory.  The  LFB is analyzed exactly like a sample, and  its
     purpose  is to  determine whether the methodology is  in control,  and
     whether  the  laboratory is capable  of making accurate and precise
     measurements at the required detection limit.

3  5  LABORATORY PERFORMANCE CHECK SOLUTION  (LPCS) - A solution  of method
     analytes used  to  evaluate the performance  of the LCEC system with
     respect  to a defined  set  of method criteria.

 3.6   LABORATORY REAGENT BLANK  (LRB)  - An aliquot of  reagent  water that  is
     treated  exactly as a  sample.   It  is exposed to  all  the  glassware,
     method solvents,  and  reagents that are used with other  samples. The
      purpose  of the LRB is  to  determine if method  analytes or  other
      interferences  are present in  the  laboratory  environment,  the
      reagents, or the apparatus.

 3 7  METHOD DETECTION LIMIT (MDL)  -  The minimum concentration  of an
      analyte that can be identified, measured and  reported with 99%
      confidence that the analyte concentration is  greater than zero.

 3.8  ORGANOMETALLIC COMPOUNDS - Compounds in which the carbon atoms of
      organic groups are bound to metal  atoms.

' 39  PRIMARY DILUTION STANDARD SOLUTION - A solution of several analytes
      prepared in the laboratory from stock standard solutions and diluted
      as needed to  prepare  calibration solutions and fortified blanks.

 3.10 SPECIATION  -  The determination of certain individual physico-
      chemical forms of  an  element.

 3.11 STOCK STANDARD SOLUTION - A concentrated solution  containing a
      single  certified  standard that is  a method analyte, or a
      concentrated  solution of a single  analyte prepared in the laboratory
      with  an assayed  reference compound.  Stock standard solutions  are
      used  to prepare  primary dilution  standards.

  3.12 QUALITY CONTROL  SAMPLE (QCS) - A  sample matrix containing method
      analytes or a solution of method  analytes in a water miscible
      solvent which is used to fortify  reagent water or  environmental
      samples.  The QCS is  obtained  from a  source external to the
      laboratory, and  is used  to check  laboratory performance with
      externally  prepared  test materials.
                                   243

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   i 1
  dil
                       n!           SOlUti°n prePared from the
                    standard  solution  and  stock standard solutions.  The CAL
                                          the
     3.14 AMPEROMETRIC DETECTOR - An electrochemical detector employing a
          rp£Sg elefr?deji whi'h is kePt at a constant potential verLs a
          reference electrode.  A small portion of the electroactive species
          JifrJI9!  ? electrode is electrolyzed (reduced or oxidized) and the
          electrolysis current is a function of the concentration of the
          eluted electroactive material.
                           ELECTRODE  (GAME> - A
                                                                       gold
4.   INTERFERENCES
     4.1
    4.2
    4.3
    4'4
 cnivl ferences m this method may be caused by contaminants in
 solvents, reagents, glassware, Teflon bottles (metals storage), and
 JrJlftS?   Pr°ef^H aP?aratus-  These interferences may lead to
 artifacts or elevated baselines in liquid chromatograms   All
 reagents and apparatus must be routinely demonstrated to be free
                                         °f the
 4.1.1   Glassware and Teflon bottles must be scrupulously cleaned
         Soak in concentrated nitric acid and -rinse thoroughly with
         organic free deionized,  distilled water.   If these
         containers are used for  free metal  and organometal  solution
         preparation and storage  they should be soaked and filled
         SS J 5 ^i1? ()[/Vl  Solut1on  of m'tric  acid for one week,
         rinsed,  sealed and stored  containing deionized,  distilled
         water.

  4.1.2   The use  of high purity reagents  and solvents  helps  to
         minimize interference  problems.   Purification  of solvents by
         distillation  in all-glass  systems may  be  required.

 Interfering contamination  may  occur when  a  sample  containing  low
 concentrations of analytes  is  analyzed immediately following  a
 sample containing relatively high  concentrations of analytes   A
 preventive  technique  is  between-sample rinsing of the  sample 'syrinqe
 and sample  loop with  methanol  and/or water.  After analysis of I
 sample containing  high  concentrations of analytes, one or more
 laboratory  reagent blanks should be analyzed.
   tho eamni   -TU" may ?e "used by contaminants that are present
... the sample.  The extent of matrix interference will  vary
considerably from source to source, depending upon the  sample type.

Electrochemical interferences are caused by species which are
electrochemically active (i.e.,  reducible at the surface of the
                                    244

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         GAME) and have retention times which are the same or very similar to
         the analytes (or because of the type of reduction process can
         produce broad chromatographic responses which obscure large portions
         of the resultant chromatograms).

         Amperometric (reductive) electrochemical detection of mercury
         analytes requires the complete removal of oxygen from the eluent and
         sample (1,2,10,11,13-15).  (Solutions in atmospheric equilibrium
         typically contain 10~4 to 10~3 M oxygen.  The specific reaction(s)
         depends on electrode material, potential, and electrolyte
         composition).  The presence of oxygen results in two distinct yet
         closely related problems:  mobile phase oxygen and  sample oxygen.
         Mobile phase oxygen contributes to onerous residual currents that
         make trace measurements  virtually impossible.  To lower mobile phase
         oxygen to acceptable  levels, deoxygenation can be facilitated by a
         combination of sparging  with inert gas  (insufficient alone) and
         warming of the eluent  solution.

         4.4.1   Sample oxygen  is retained on  reversed-phase columns (not
                 eluted in the  void volume) and  elutes as a broad, tailing
                 band.  Its retention time is  independent of the
                 concentrations  of the mobile  phase constituents; therefore,
                 manipulation  of the elution position is difficult.  Oxygen
                 is detected as  a peak when only the mobile phase is purged
                  (sparged) with  inert gas.  Elimination of the  sample oxygen
                  interference  can be accomplished by purging with an inert
                 gas  prior to  injection.  The  sample is placed  in a 3 to  5 ml
                 vial,  as shown in Figure 2b,  and purged with a stream of
                  inert  gas for « 5 min.   The sample aliquot is  introduced
                  into the sample injection loop  via  a closed  system to
                 prevent reentry of oxygen  .

          4.4.2   Mobile phase  oxygen.   Both positive and  negative oxygen
                  peaks  can  arise in LCEC.  The former occurs  when the sample
                  solution  is not purged  with  an  inert gas.  A negative oxygen
                  peak occurs when the  mobile  phase  contains more oxygen  than
                  the  sample.   The negative peak has  the  same  retention time
                  and  shape  but may be  lower  in magnitude  then the positive
                  oxygen peak.
5.   SAFETY

     5.1  The toxicity or  carcinogenicity of  each reagent  used in this method
          has not been precisely defined; however,  each  chemical compound must
          be treated as a  potential  health hazard.   The  laboratory is
          responsible for maintaining  a current awareness  file of OSHA
          regulations regarding the safe handling of the chemicals specified
          in this method.   A reference file of material  safety data  sheets
          should also be made available to all  personnel  involved in the
          chemical  analysis.   Additional  references to laboratory safety
          should be identified and made available for the information  of  the
          personnel using this method.


                                     245

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           The current OSHA standard for organo (alkyl) mercury is 0.01 mg of
           organo (alkyl) mercury per cubic meter of air (mg/m*)  averaged over
           an eight-hour work shift with a ceiling level of 0.04 mg/m?.   Organo
           (alkyl) mercury can affect the body if it is inhaled,  cSmes 1nUrgan°
           contact with the eyes or skin, or is swallowed.   It may enter the
           body through the skin.  Skin that becomes contaminated with organo
           (alkyl) mercury should be immediately washed or showered with soao
           or mild detergent and water.

           If organo (alkyl) mercury compounds are spilled  or leaked:

                   1.   Remove ignition  sources.

                   2.   Ventilate area of spill  or  leak.

                   3.   If in the solid  form,  collect for reclamation  or
                       disposal.
          5.1.1


          5.1.2

          5.1.3


          5.1.4
6.
              4.   If in the liquid form,  absorb on  paper towels.
                  Evaporate in  a safe  place  (such as  a fume hood).

              The  addition  of the complexing  agent, 2-Mercaptoethanol  (2-
              ME),  should be performed in  a hood.

              The  eluent pH should be  adjusted  in a hood.

              Precautions must  be taken in the  preparation  of the GAME to
              prevent aerosols  and spills.

              Disposal  of waste  (solvents, analytes, etc.)  from the
              system must be  according to local regulations.

APPARATUS AND EQUIPMENT (Some specifications are suggested)

6.1  HIGH PERFORMANCE  LIQUID CHROMATOGRAPH

     6.1.1   An HPLC system designed for pumping solvents at precisely
             controlled flow rates and pressures.   The system should be
             capable of injecting 10- to 200- juL aliquots.

             NOTE:  Amperometric reductive electrochemical  detection of
             the mercury analytes requires the complete removal  of oxygen
             from the eluent and samples.   Copper tubing (1/8 in.)  may be
             used for lines from the purge gas (Ar) tank to the  mobile
             phase flask.   Fittings and tubing (1/16  in. o.d )
                                                            .   .
                  constructed  ^om type  316  stainless  steel  should  be  used  for
                  all  other  connections  '10f11'14'15.

         6.1.2    Analytical column— 25  cm x 4.6 mm  I.D.  stainless  steel
                  packed with  LiChrosorb RP-18  (5 urn irregularly  shaped
                                     246

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             particles) hydrocarbon phase  (C-18  (ODS)) bonded silica  (EM
             Science)  or  equivalent.

     613    Guard  column—70 mm  x 4.6 mm  I.D. stainless  steel packed
             with Perisorb RP-18  (30-40 urn)  (EM  Science)  or equivalent.

     6.1.4    Pre-column  (saturator column)—70 mm  x  4.6 mm  I.D.  stainless
             steel  packed with  spherical silica  (18  urn)  (EM Science)  or
             equivalent.

     6.1.5    Electrochemical detector (potentiostat/current amplifier).

             6.1.5.1   Working  electrode.  - GAME.

             6.1.5.2   Reference  electrode -  Ag/AgCl 3M NaCl).

     6.1.6    Other  columns  or detectors  may  be  used  if the  requirements
             of Sect.  10.5  can  be met.

6.2  Strip  Chart Recorder - Variable speed.

6.3  Balance—Analytical, capable of accurately weighing  to the  nearest
     0.01 mg.

6.4  General purpose laboratory,  top-loading, metric, automatric
     calibration, full range-taring readibility to 0.01  g.

6.5  Filtration Apparatus—To filter samples and mobile  phases used in
     HPLC,  use 250 ml glass reservoir (connects to 1 L bottle or vacuum
     flask), funnel base and stopper, clamp,  stainless steel holder,
     screen  and Teflon gaskets (Figure 3).  Recommended  are 47-mm filters
     (Millipore Type HA, 0.45 /xm, for water  and Millipore  Type FH, 0.5-
     nm, for organics or equivalent).

6.6  GLASSWARE

     6.6.1   Three-neck  distillation flask with all  equivalent height
             necks  of I  24/40 joints.

     6.6.2   Condenser,  Graham,  Drip Tip  Inner  (bottom)  and Outer (top) I
             24/40  Joints.  .

     6.6.3   Reaction vials—5-mL capacity serve  as  sample cells and
             purge  gas saturation chambers.

     6.6.4   Bubbler—I  29/42  joints  (frit not  required).

     6.6.5   Connecting  Adapter, I 24/40  joint  (condenser  end).

 6.7  Standard  1-L  heating mantle.
                                 247

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      6'8
                                          °f maintain1n9 temperatures within
      6.9  Thermistor probe— Heavy duty laboratory style (~20 cm long).

      6.10 Septa— White rubber for I 24/40 joints.

      6.11 Refrigerated Recirculating Cooler— With sealable reservoir
          temperature controller, recirculating pump,  air cooled refrigeration
          (±  l.OC). Circulation is in a closed loop configuration  (system).

      6.12 SYRINGES

          6.12.1  Hypodermic syringe— 5 mL glass (gas  tight).

          6.12.2  Microliter gas tight syringe— 50 /*L  an 100 ;uL needle:  90°
                  blunt tip, 2"  long,  0.028"  OD (22S gauge),  no  electrotaper.

7-   REAGENTS AND CONSUMABLE MATERIALS

     7.1  Acetonitrile  (CASRN-75-05-8)— HPLC  grade.

     7.2  Deionized, distilled water  (CASRN-7732-18-5):  Prepared by passing
          distilled  water through mixed  bed cation  and anion exchange resin?.
          ^?i^??nZed;  dHStilled/^?r  for  a11  ^agents, eluent solutions,
          calibration standards  and dilutions.   In  this method, the term
          deionized  distilled water will  be used  interchangeably with reagent
          mShL(H'?"^ater-1-/hIch,an  interferent is not observed at the
          method  detection  limit  of the compounds of interest).

     7.3  Inert Gas— High purity  argon or helium for degassing eluents and
          samp i es .

     7.4  HPLC MOBILE PHASE

          7.4.1   Acetic acid, Glacial (CASRN-64-19-7)— Ultrex grade (for
                 eluent pH adjustment).                       y     v

         7.4.2   Ammonium hydroxide (CASRN-1336-21-6)-Ultrex grade,  20% (for
                 eluent pH adjustment).

         7.4.3   Eluent:   Mix 600 g of methanol (Sect.  7.4.5)  and 400  g  water
                 (Sect. 7.2.),  pH 5.5, add 200 juL of 2-mercaptoethanol to 1-
                 L of solution.   (The total volume is  « 1.125 L.)   Allow to
                 cool,  adjust the pH,  transfer to a 1-L  volumetric  flask
                 (refrigerate the remainder)  and add the complexing agent
                 (Sect.  7.4.4)).

         7.4.4   2-Mercaptoethanol  (CASRN-60-24-2)-CAUTION:   Combustible
                 stench,  harmful  vapor;  store in  hood.
                                    248

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     7.4.5   Methanol (CASRN-67-56-l)--High purity solvent, HPLC grade.

7.5  Ethylmercury chloride (CASRN-107-27-7).

7.6  Mercuric chloride (CASRN-7487-94-7).

7.7  Mercury, metal (CASRN-7439-97-6)—Triple distilled.

7.8  Methylmercury chloride (CASRN-115-09-3).

7.9  Nitric acid, cone. (CASRN-7697-37-2)--sp gr 1.41.

7.10 Nitric acid, 1:1: Add 50 ml cone. HNO, (Sect.  7.9) to 40 ml of
     distilled, deionized water (Sect. 7.2), cool, and dilute to 100 ml.

7.11 Phenylmercury acetate (CASRN-62-38-4).

7.12 Sodium chloride  (CASRN-7647-14-5)—CrystalI, ACS grade, 3M.  Dissolve
     43.8 g of sodium chloride in deionized, distilled water  (Sect. 7.2)
     and dilute to 250 ml.

7.13 Stock standard  solutions  (1000 ng/ml) of  the  mercury analytes  may
     be prepared  from reagent  grade chemicals.  Typical metal stock
     solution preparation procedures  follow.   The  amount  of organic
     solvent, acetonitrile,  (Sect. 7.1) is added as needed in order to
     dissolve the particular mercury  organometal.

     7.13.1  Mercury (II) solution, stock, 1 mg/mL:  Dissolve 0.1354 g of
             mercuric chloride (Sect.  7.6) in  deionized,  distilled  water
             with stirring until completely  dissolved.  Transfer to a
             100  ml  volumetric flask  and  dilute  to volume. Transfer to a
             125-mL  Teflon bottle  and refrigerate.  This  solution can  be
             stored  and used for at least six  months.

     7.13.2  Methylmercury solution,  stock,  1  mg/mL methylmercury:
             Dissolve 0.5822 g of  methyl mercuric chloride (Sect. 7.8)  in
             deionized, distilled  water (minimum volume of water added
             initially) with constant stirring.   Add  acetonitrile  (Sect.
             7.1) slowly  until dissolution is  complete.   In  500 ml  total
             volume, approximately 10% (V/V) CH3CN is  sufficient to
             dissolve this  amount  of  material.  Dilute to 500 ml total
             volume  and  transfer to  a Teflon bottle for refrigeration  and
              storage. This  solution  can  be  stored and used  for at  least
              six months.

      7.13.3   Ethylmercury solution,  stock, 1 mg/mL ethylmercury:
              Dissolve 0.5771 g of  ethylmercuric chloride  (Sect. 7.5)  in
              deionized distilled water with  constant  stirring.   Because
              Ethylmercuric chloride is difficult to dissolve in water,
              add acetonitrile  (Sect.  7.1) until  there is  complete
              dissolution.  Approximately 200 ml of 40% (V/V)  acetonitrile


                                 249

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           7.13.4
          NOTE:
         (Sect. 7.1), is needed.  Dilute to 500 mL with distilled,
         deionized water (Sect. 7.2), transfer to a Teflon bottle for
         refrigeration and storage.  This solution can be stored and
         used for at least six months.

         Phenylmercury solution, stock,  1 mg/rnL phenylmercury:
         Dissolve 0.6063 g of phenylmercuric acetate (Sect.  7 in
         Add approximately 10% (V/V) acetonitrile (Sect.  7.1) to aid
         in dissolution.  Dilute to 500  ml with deionized, distilled
         water (Sect. 7.2)  and refrigerate in  a Teflon bottle.  This
         solution can be stored and used for at least six months.

         For analysts who do  not routinely perform mercury analyses
         or do not wish  to  generate excessive  amounts of  mercury
         waste,  the stated  volumes  and/or amounts of organometal
         salts should be reduced proportionately.   Primary and
         secondary dilution standards  may be diluted to 10 mL or 25
         ml of solution  to  avoid this  problem.
8-   SAMPLE COLLECTION. PRESERVATION AND HAMni TMfi

    8'2
          rn      n lectlon:-?aniples should be collected in duplicate in amber
          colored glass containers or glass containers wrapped in aluminum
          collection containers should not be Prerinsed with sample prior to
8.1.1
8.1.2
                  When sampling from a water tap,  open the tap and allow the
                  system to flush until  the water  temperature has stabilized
                  Adjust the flow to about 500 mL/min  and collect duplicate
                  samples from the flowing stream.                  MH'".*HJ

                  When sampling from an  open body  of water,  fill  the  sample
                  container with water from a representative area.  Sampling
                  equipment,  including automatic samplers, must be  free  of
                  plastic tubing and other components  that may leach
                  interferents  into  the  water.  Automatic  samplers  that
                  composite samplers over  time must  use refrigerated
                  glass/Teflon  sample  containers.
                                        be  iced  or refrigerated  at
                                until  filtration.   The samples
                              poss1ble  
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     8.4   FIELD BLANKS

          8.4.1   Processing a field reagent blank (FRB)  is  recommended along
                  with  each sample set,  which is  composed of the samples
                  collected from the same general  sample  site at approximately
                  the same time.  At the laboratory,  fill a  sample container
                  with  reagent water, seal,  and ship  to the  sampling site
                  along with the empty sample containers.  Return the FRB to
                  the laboratory with filled sample bottles.

          NOTE:   The prevention of contamination and losses is of paramount
                  importance in organomercury speciation  and analysis.
                  Potential sources of contamination  in the  laboratory
                  environment are dust,  reagent impurities,  and sample contact
                  with laboratory apparatus (resulting in contamination by
                  leaching or surface desorption).  Depletion of mercury via
                  adsorption onto container surfaces  must also be considered.

9.   CALIBRATION AND STANDARDIZATION

     9.1  Establish LCEC operating conditions equivalent  to those indicated in
          Table 1.  Calibrate the HPLC system using the external standard
          technique.

     9.2  EXTERNAL STANDARD CALIBRATION PROCEDURE

          9.2.1   An external standard is a solution containing a known amount
                  of a pure compound that is analyzed with the same procedures
                  and conditions that are used to analyze samples containing
                  that compound.  From measured detector responses to known
                  amounts  of the external standard, a sample concentration of
                  that compound can  be calculated from measured detector
                  response  to that  compound  in a  sample  analyzed with the same
                  procedures.

          9.2.2   At least  three calibration standards are  needed.  One should
                  contain  each  analyte at a  concentration near to but greater
                  than  its  method detection  limit  (MDL)  (Table 2); the  other
                  two  should  bracket the concentration range expected  in the
                  samples  or define the working range of the detector.  For
                  example,  if the MDL is 1.0 M9/L and  a  sample  is  expected  to
                  contain  approximately  5.0  Atg/L,  aqueous standards  should  be
                  prepared at concentrations of 2.0 p.g/1, 5.0  p.g/1,  and
                  10.0
           9.2.3    Inject  0.1 mL  of  each  calibration  standard  and tabulate  peak
                   height  or area response  versus  the concentration  of  the
                   standard.  The results are  to be used to  prepare  a
                   calibration  curve for  each  analyte by plotting the peak
                   height  or area versus  the concentration.
                                      251

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           9.2.4    The working calibration  curve  must  be  verified  on  each
                   working day by the  measurement of one  or more calibration
                   standards  (and when/if the working  electrode  is changed
                   between analyses).   If the response for  an  analyte varies
                   from the response predicted  by the  calibration  curve  (Sect.
                   9.2.2)  by  more than ± 10%, the test must be repeated  using
                   a  fresh calibration standard.   If the  results still do not
                   agree (i.e., the response is off  by more than
                   ± 10%), generate a new  calibration curve for each analyte.
                   (Assuming  that the  electrode surface is  "fatigued", the
                   analyst should change  the GAME  before  proceeding further)
                   Generally  the  electrode  can be  used  3  to 4 days before the
                   old  amalgam surface has  to be  removed.

          9.2.5    Single  point calibration is sometimes  an  acceptable
                   alternative to  a calibration curve.   Single point  standards
                   should  be  prepared  from  the primary dilution standard
                   solutions.   The single point calibration  standard(s) should
                   be prepared at  a concentration that produces a response
                  close (± 10%)  to that  of the unknowns.

10.  QUALITY CONTROL

     10.1 Each laboratory using this method is  required to operate a quality
          control  (QC) program.  The minimum requirements of this  program
          consist of the following:   an initial  demonstration  of laboratory
          capability and regular analyses of laboratory reagent blanks
          (including sol vent/eluent  blanks) and laboratory fortified blanks
          (laboratory QC samples).  The laboratory must maintain records to
          document the quality of the  data  generated.

     10.2 Initial demonstration of low system  (detector)  background response
          (i.e.,  minimum residual (background)  current and  low noise  output).

          10.2.1   The system  must operate with  the minimum  absolute  background
                  current  in  order to  optimize  sensitivity. Detection of
                  analytes at low concentrations  (e.g., 20  /zg/L) can  result
                  in  chromatograms being  superimposed  on  a  background current
                  which may exceed the peak heights  of the  analytes.   High
                  background  currents  may increase instrumental susceptibility
                  to  flow  variation noise and possibly lead to nonlinear
                  deviations  in the calibration curve(s).   The Faradaic
                  response, which may  arise from  an  electrochemical reaction
                  of  the electroactive impurities  in the  mobile phase (eluent)
                  is  the principal component of the  current produced  at a
                  constant potential  detector.  The most  common sources of
                  background  current are  the oxidation/reduction of the eluent
                  or  buffer salts, oxygen (either  eluent  or sample),  ferrous
                  and/or ferric iron and  other metals  ions.
                                     252

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     10.2.2  The noise associated with an electrochemical  detector is
             dependent on the magnitude of the background  signal.   In
             general,  the higher the background,  the higher the noise.
             The ratio of the noise to the background current stays about
             the same.  Noise can be random or periodic and superimposed
             on the steady state background signal.   The noise represents
             the collective contributions from pump  pulsations, flow cell
             hydrodynamics, surface reactions, static electricity, power
             line noise, and electronic signal amplification.  Noise can
             be minimized by (a) obtaining pulseless flow, (b) frequent
             system passivation, (c) proper maintenance of pump seals  and
             check values in order to minimize flow  fluctuations,  (d)
             proper system grounding, and (e)  careful scrutiny of the
             working electrode surface—a smooth, shiny mirror-like
             finish is desirable.

10.3 Another possible source of noise is the reference electrode which
     provides a stable, reproducible voltage to which the  working
     electrode potential maybe referenced.  The potential  value should
     not vary with time and should be reproducible from electrode to
     electrode.  Leaks can occur due to drying and cracking of the porous
     plug.  As a consequence, the internal electrolyte concentration
     changes and subsequently the reference potential.

10.4 Air bubbles trapped around and/or between the working and reference
     electrode can cause noise, random as well as periodic with constant
     amplitude and frequency.

10.5 Initial demonstration of laboratory accuracy and precision.  Analyze
     seven replicates of a laboratory fortified blank solution
     (laboratory QC samples) containing each analyte at concentration
     levels near the low calibration standard.  (See regulations and
     maximum contaminant levels for guidance on appropriate
     concentrations.)

     10.5.1  Prepare each replicate by adding an appropriate aliquot of
             the primary/secondary dilution standard solution, or other
             certified quality control sample, to reagent water.  Analyze
             each replicate according to the procedure described in
             Sect. 11.

     10.5.2  Calculate the measured concentration of each analyte in each
             replicate and the mean accuracy (as mean percentage of true
             value) and precision (as relative standard deviation, RSD)
             of the seven measurements of each analyte.

     10.5.3  For each analyte at 50 M9/U the mean accuracy expressed as
             a percentage of the true value is approximately 93% and the
             RSD is <  11%.
                                 253

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      10.5.4  Analysts should develop and maintain a system of control
              charts to plot the precision and accuracy of analyte
              measurements over time.

      10.5.5  It is recommended that the laboratory periodically document
              and determine its detection limit capabilities for the
              analytes of interest.  NOTE:  The determination of the
              method detection limit (MDL) for this method was performed
              under special (ideal) experimental  conditions in order to
              achieve the desired level.  The GAME was specially prepared
              and the system was allowed to equilibrate over a 4 day
              period.  Eluent flow was maintained at approximately 0.3-
              0.4 mL/min.   The current sensitivity was increased until the
              lowest setting was achievable.   The MDL of each analyte was
              calculated  (Table 2)  using procedures described in12.  The
              listed MDLs  should be achievable or lower with commercially
              available instrumentation, which include improved solvent
              delivery systems,  new transducer cell  designs,  and
              installable  in-line deoxygenators that remove at least 99%
              of the oxygen in the  sample and mobile phase without
              affecting their integrity.  Analyte detection at regulatory
              levels should be achievable.

 10.6  Laboratory Reagent Blanks  (LRB)  Before  processing any samples,  the
      analyst  must  demonstrate that all  glassware and reagent
      interferences are under control.   Each  time a  set of reagents  is
      changed  (fresh eluent added)  or  a  new working  or reference electrode
      installed,  a  LRB  must be analyzed.   If  within  the retention  time
      window of  any analyte of interest  the LRB produces  a peak that would
      prevent  the determination  of  that  analyte,  determine the  source  of
      contamination and eliminate the  interference before  processing
      samples.

 10.7  A single laboratory fortified  blank containing  each  mercury  analyte
      at a concentration as  specified  in Sect.  10.5 must  be analyzed with
      each set of samples.   Evaluate the accuracy of  the measurements.
      Any problems  must be  located  and corrected  before further  analyses
      are performed.

 10.8 A field reagent blank  should be analyzed with each set of  field
      samples.  Data/information from these analyses will  be used to help
     define and determine contamination related to field  sampling and
     transportation activities.

10.9 Each quarter, replicate laboratory fortified blanks must be analyzed
     to determine the precision of the laboratory measurements.  These
     data will be used in documenting data quality.

10.10 Each quarter, the laboratory must analyze a quality control sample
      obtained from an external source.   A quality control sample should
      be analyzed each time a new set of standards are used.  The entire
                                254

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           analytical  procedure must be checked,  if unacceptable accuracy data
           is obtained.

     10.11 The laboratory must analyze an unknown performance evaluation
           sample (if available) at least once per year.   Results for each
           analyte must  be within established acceptance  limits.

11.   PROCEDURE-LIQUID CHROHATOGRAPHY WITH ELECTROCHEMICAL DETECTION (LCEC)

     11.1  Table 1 summarizes the recommended operating conditions for LCEC
           and presents  analyte retention times observed  using this method.
           The operating conditions may be changed (e.g., flow rate, modifier
           percent, electrode potential, etc.) in order to enhance the
           separation or detection.

     11.2  CHROMATOGRAPHIC PROCEDURES

           11.2.1   Electrode (cell) preparation:  The cell should be polished
                    before use  .   From  beginning  use,  and  regularly during
                    its  use, a new mercury film must be deposited on the gold
                    disk.  Follow the procedure for electrode preparation as
                    stated in the operator's manual.

                    Mercury application—This process should be carried out in
                    a tray in the event of an accidental  spill.  Follow the
                    precautions for handling mercury.  NOTE:  Mercury has a
                    high vapor pressure and should always be stored in a
                    closed container or under water.  Prior to mercury
                    application rinse the electrode surface with a small
                    amount of methanol and air-dry before proceeding.

                    Deposition of the mercury film on the gold disk
                    is accomplished by placing a small drop of mercury on the
                    gold surface.  Cover the entire surface with mercury using
                    a disposable pi pet.  Wait ~ 3-5 minutes, then remove the
                    excess mercury gently with the sharp  edge of an index
                    card.  (This step may be repeated 2 to 4 times).  The
                    mercury surface can be smoothed with  a soft tissue (lens
                    tissue works best) to obtain a shiny, mirror finish.
                    (DISPOSE OF WASTE MERCURY CAREFULLY.)  If excess mercury
                    is left on the electrode, there is a  possibility of a
                    short circuit with the auxiliary electrode (stainless
                    steel top).  In some instances, the insertion of a second
                    gasket between the electrode cube halves can remedy the
                    problem.  Sometimes it is not necessary to remove the old
                    amalgam surface before a fresh mercury surface can be
                    applied.  The new mercury surface can be formed on top of
                    the old amalgam.  Follow the same procedure as for a fresh
                    gold surface.
                                      255

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                     The amalgam requires a period of equilibration following
                     its formation.   Usually allowing the amalgam to rest
                     overnight is sufficient.
      11.3   SYSTEM OPERATION
            11.3.1
            11.3.2
           11.3.3
           11.3.4
12.   CALCULATIONS
          The instrumentation should be turned on and allowed to
          become stable before beginning.

          The following chromatographic start-up procedure is
          recommended for reductive LCEC analysis f2.
          DEOXYGENATION:   Before initiating flow through the LC
          system,  the eluent, which is placed in a 2-L distillation
          flask,  is refluxed at 40 ± 5°C while being purged
          vigorously with inert gas (argon  or helium) for
          approximately 1-2 hours (Figure 2A).   Then the degassed
          mobile phase is pumped through the LCEC system to force
          out any oxygen  entrained in the stationary phase pores
          (column  interstices).   Degassing  the  system may require
          100-150  mL of mobile phase.  The  system must be flushed
          thoroughly.   Next,  the working electrode is turned on
          (after flushing)  using the least  sensitive gain setting.
          The current  is  monitored until  the background current has
          stabilized in the desired range,  usually 80 to 100 nA.

          Sample degassing  is necessitated  when  working at
          potentials more negative than  -0.1 V  for the GAME10'14'15.
          Care must be taken  in  order to preserve the sample's
          original  composition.   The purge  gas  should be
          presaturated with mobile phase or water and flowed gently
          through  the  sample  to  minimize its evaporation.   Degassing
          a 3.5-4  mL sample requires approximately 5 min.

          Sample injection  requires  a closed system.    The
          injection valve inlet  is  immersed  in the filtered  and
          degassed  sample solution  and the  sample aliquot  is  slowly
          drawn into the  injection  loop  by  gentle suction
          (Figure  2C)1'11'1"'Ti.   Exposure  to  oxygen is avoided and
          the  integrity of  the closed  system is preserved.
     12.1
     12.2
Calculate analyte concentrations in the sample by utilizing the
calibration curve(s) generated from the responses of analytes in
standard solutions.

Data should be rounded to the tenths place and reported in
micrograms per liter.
                                     256

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13.  PRECISION AND ACCURACY

     13.1  In a single laboratory the MDL12 was determined  for each  analyte.
           Seven aliquots of the fortified distilled water sample were
           measured and the results used to calculate the MDL at the 99%
           confidence level.  The calculated MDLs (Table 2) ranged from 0.8 to
           1.9 M9/L.

     13.2  In a single laboratory, analyte recoveries from laboratory
           distilled water, tap water, and two groundwaters were determined at
           analyte concentrations ranging from 50 to 200 /zg/L (Tables 3-5).
           Recoveries averaged 90 ± 7% RSD with comparable values obtained
           over the entire range of concentrations.  The standard deviation of
           the measurements on all waters was approximately 1.52 jug/L with an
           RSD of approximately 0.64%.

14.  REFERENCES

      1.   Evans, 0. and McKee, 6.D., Analyst. 1987, 112, 983.

      2.   Evans, 0. and McKee, G.D., Analyst. 1988, 113, 243.

      3.   MacCrehan, W.A., Durst, R.A., and Bellama, J.M., Anal. Lett.. 1977,
           10, 1175.

      4.   MacCrehan, W.A., Durst, R.A., and Bellama, J.M., Nat. Bur. Stand.
           (U.S.), Spec. Pub!., 1977, No.519, 57.

      5.   MacCrehan, W.A. and Durst, R.A., Anal. Chem.. 1978,  50, 2108.

      6.   MacCrehan, W.A., Anal. Chem.. 1981, 53, 74.

      7.   Holak, W., >L. Liq. Chromatoqr.. 1985,  8, 563.

      8.   Holak, W., Analyst. 1982, 107, 1457.

      9.   Krull, I.S., Bushee, D.S., Schleicher, R.G., and Smith, S.B., Jr.,
           Analyst. 1986, 111, 345.

     10.   "Installation/Operations Manual for Amperometric Controller and
           Transducer Package," Bioanalytical Systems, West Lafayette, IN,
           1984.

     11.   Jacobs, W. Curr. Sep. 1982, 4, 45.

     12.   Glaser, J.A., Foerst, D.L., McKee, G.D., Quave,  S.A., and Budde,
           W.L., Environ. Sci. Techno!.. 1981, 15, 1426.

     13.   Lewis, J.Y., Zodda, J.P., Deutsch, E., and Heineman,  W.R., Anal.
           Chem.. 1983, 55, 708.
                                      257

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14.   Bratin, K., and Kissinger, P.T., Talanta. 1982, 29, 365.

15.   Bratin, K., and Kissinger, P.T., J. Lia. Chromatoqr.. 1981, 4,
      (Suppl.2), 321.
                                258

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                 TABLE  1.  PRIMARY CHROMATOGRAPHIC CONDITIONS
Absolute Retention Time, Min
Analyte
Mercury (II)
Methyl mercury
Ethyl mercury
Phenyl mercury
(a)
3.3
3.5
4.2
5.3
(b)
5.4
5.9
6.9
9.2
         (a)   Flow rate - 1.0 mL/min.
         (b)   Flow rate - 0.6 mL/min.

              Primary Conditions:

               Analytical  Column:  25 cm x 4.6 mm i.d.,  EM Science LiChrosorb
                                 RP-18  (5/zm)

               Pre-Column:   Saturator Column,  70 mm x 4.6 mm i .d. (18 /xm) EM
                           Science

               Guard  Column:   70 mm X 4.6 mm i.d.,  EM Science
                              Peri sorb RP-18  (30-40
               Mobile  Phase:   Isocratic elution - 60% (w/w)  methanol ,
                             0.01%  (V/V) 2-mercaptoethanol , pH 5.5 acetate
                             buffered

               Flow Rate:   1.0  mL/min  or 0.6 mL/min*

               Injection  volume:   100  juL

               Detector:  Electrochemical  (GAME);  - 0.800 V vs.  Ag/AgCl


*The optimum flow rate is «  i.o mL/min.  However,  in  some instances it  is
desirable to use a lower flow rate.  A flow rate  of 0.6 mL/min allows a
slightly better separation between Hg(II) and CH,Hg+ than a  flow  rate  of 1.0
mL/min.  The lower flow rate does, however, result in approximately a 6-12%
decrease in the analytical signals.
                                      259

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                  TABLE 2.  METHOD DETECTION LIMIT  (MDL)  (a)
Parameter
Retention time, min
MDL*, /tg/L
Hg(II)
=5.3
*1.8
CH3Hg+
=5.8
*1.9
C2H5Hg+
=6.9
=1.7
C6H5Hg+
=9.5
=0.8
(a)    Experimental  conditions:  60% (W/W) CH3OH,  pH 5.5 acetate buffer,  200 pi
      of 2-mercaptoethanol  (ME).  Potential,  - 0.800V vs. Ag/AgCl;  flow rate
      0.6 mL min- 1.  Other conditions: 100 fj,l  sample  loop;  « 45.5°C, « 2250
      Ib in  "2; current offset ca. - 20 nA; GAME; and  LiChrosorb  RP-18  (5 jum)
      (25cm  x 4.6mm i.d.).   *For the MDL  determination seven replicate
      measurements  were made on  solutions containing each analyte (12).  The
      fortified  value  (true  concentration)  of each  analyte is 10
                                     260

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     TABLE 3. RECOVERY OF ANALYTES FROM REAGENT WATER (a)
Mixture
A



B



C



Hg Analytes
HgdD
CH3Hg+
C2H5Hg+
C6H5Hg+
Hg(H)
CH3Hg+
C2H5Hg
C6H5Hg+
Hg(ll)
CH3Hg+
C2H5Hg'f
C6H5Hg+
Hg added
M9 L'1
120
120
120
120
150
150
150
150
250
250
250
250
Hg determined
M9 L"1
(mean ± s.d.)
113.2 ± 2.1
117.1 ± 1.4
118.4 ± 1.5
123.2 ± 0.8
153.0 ± 1.3
154.6 ± 1.4
154.4 ± 1.4
143.3 ± 0.3
249.0 ± 0.8
255.7 ± 1.6
255.2 ± 2.2
250.5 ± 0.8
Recovery, %
(mean ± s.d.)
94.4 ± 1.8
97.6 ± 1.2
98.7 ± 1.3
102.6 ± 0.6
102.0 ± 0.9
103.1 ± 1.0
103.0 ± 0.9
95.5 ± 0.2
99.6 ± 0.3
102.3 + 0.6
102.1 ± 0.9
100.2 ± 0.3
(a)   Three determinations per solution;  40% (W/W)  methanol;
     flow rate =1.0 mL/min.
                             261

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TABLE 4.  RECOVERY OF ANALYTES FROM GROUNDWATER (LAKOTA HILLS) (a)
Mixture
A



B



C



D



E



F



Hg Analytes
Hg(H)
CH3Hg+
C2H5Hg+
C6H5Hg+
Hg(ii)
CH3Hg+
C2H5Hg*
C6H5Hg+
Hg(H)
CH3Hg*
C2H5Hg+
C6H5Hg*
Hg(ii)
CH3Hg+
C2H5Hg+
C6H5Hg+
Hg(ii)
CH3Hg+
C2H5Hg+
C6H5Hg+
Hg(ii)
CH3Hg+
C2H5Hg+
C6H5Hg+
Hg added
M9 L"1
50
50
50
50
70
70
70
70
90
90
90
90
120
120
120
120
150
150
150
150
200
200
200
200
Hg determined
M9 L'1
(mean ± s.d.)
38.5 ± 0.3
45.8 ± 0.0
51.9 ± 0.2
41.2 ± 0.4
58.1 ± 0.1
65.0 ± 3.5
64.5 ± 2.4
68.5 ± 0.8
72.9 ± 0.3
84.2 ± 3.0
85.8 ± 1.2
98.0 ± 1.8
99.8 ± 0.0
114.5 ± 1.9
115.4 ± 1.0
118.5 ± 1.0
143.9 ± 0.4
143.3 ± 0.9
144.9 ± 0.2
145.9 ± 0.7
200.1 ± 2.3
192.8 ± 1.3
190.1 ± 1.6
185.1 ± 1.2
Recovery, %
(mean + s.d.)
77.0 ± 0.6
91.6 ± 0.0
103.8 ± 0.4
82.4 ± 0.9
83.0 ± 0.2
92.9 ± 5.0
92.1 ± 3.5
97.9 ± 1.1
81.0 ± 0.3
93.6 ± 3.4
95.3 ± 1.3
100.0 ± 2.0
83.2 ± 0.0
95.4 ± 1.6
96.1 ± 0.8
98.8 ± 0.9
95.9 ± 0.2
95.5 ± 0.6
96.6 ± 0.1
97.3 ± 0.5
100.0 ± 1.1
96.4 ± 0.7
95.1 ± 0.8
92.6 ± 0.6
  (a)   Two determinations per solution;  40% (W/W) methanol;
       flow rate =1.0 mL/min.
                               262

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          TABLE   5.   RECOVERY OF ANALYTES FROM GROUND WATER (CLERMONT COUNTY, OH)
                             AND TAP WATER (CINCINNATI, OH) (A)
                      Hg added
Mixture  Hg Analytes
 Hg measured
in groundwater
    W L'1
 (mean  ±  s.d.
Hg measured
in tap water
   M9L'1
(mean ± s.d.)
   Recovery,  %   Recovery,  %
(mean ± s.d.)  (mean ± s.d.)
A Hg(II)
CH3Hg+
C2H5Hg+
C6H5Hg+
B Hg(II)
CH3Hg+
C2H5Hg*
C6H5Hg+
C Hg(II+)
^t CH3ng
P C2H5Hg+
C6H5Hg+
D Hg(II)
CH3Hg+
C2H5Hg+
C6H5Hg+
50
50
50
50
100
100
100
100
120
120
120
120
150
150
150
150
52.3 ± 2.0
43.6 ± 2.0
42.7 ± 3.9
49.0 ± 2.3
98.6 ± 4.0
93.3 ± 3.5
97.0 ± 2.6
94.9 ± 3.0
120.1 ± 0.5
111.5 ± 1.3
109.4 ± 4.0
120.6 ± 0.4
—
	
—
— — —
49.5 ± 4.5
51.7 ± 3.3
44.8 ± 5.4
47.6 ± 4.6
100.7 ± 0.9
103.1 ± 1.9
88.0 ± 6.5
99.3 ± 0.8
—
—
—
—
150.5 ± 3.6
153.3 ± 2.4
129.5 ± 3.8
138.9 ± 2.0
104.6 ± 4.0
87.2 ± 4.3
85.4 ± 7.9
96.8 ± 4.5
98.6 + 4.0
93.3 ± 3.5
97.0 ± 2.6
94.9 ± 3.0
100.1 ± 0.4
92.9 ± 4.1
91.2 ± 3.5
100.5 ± 0.3
	
	
—
___
99.0 ± 9.0
103.4 ± 6.7
89.6 ±11.0
95.2 ± 9.1
101.9 ± 0.9
103.1 ± 1.9
88.0 ± 6.5
99.3 ± 0.8
—
—
—
—
100.3 ± 2.4
102.2 ± 1.6
86.3 + 2.6
92.6 ± 1.3
   (a)  Three determinations per  solution; 60%  (W/W) methanol,  flow rate =1.0 mL/min.
                                             263

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                  100-1
                   80 -
               V)
                   60 -
               c
               CO

               O


               I

               I  40
                    20  -
                         0     2

                          Retention Time (min.)


Figure 1.  Separation of four charge-neutral mercury analytes.
Conditions:  eluent,  60% (W/W)  methane!,  column, LiChrosorb RP-18 (5 pi),  25  x
0,46 cm; pH 5.5 acetate buffer;  0.01% (V/V) 2-ME; flow rate, 1.0 ml min'1;
standard mixture,  10  /zg ml/1 each analyte; sample loop,  100  pL.   (1) Hgll; (2)
methylmercury; (3) ethylmercury; and  (4)  phenylmercury.
                                     264

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265

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Stainless Steel
Screen and
Teflon Gasket
Rubber Stopper
To Vacuum
                                          250 ml Reservoir
                                              Clamp
                                             1  Liter
                                             Vacuum Flask
        Figure 3.  Sample and Mobile Phase Filtration Apparatus

                          266

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                METHOD 245.5

    DETERMINATION OF MERCURY IN SEDIMENTS
 BY COLD VAPOR ATOMIC ABSORPTION SPECTROMETRY
Edited by Larry B. Lobring and Billy B. Potter
          Inorganic Chemistry Branch
          Chemistry Research Division
                 Revision 2.3
                  April 1991
  ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
       OFFICE OF RESEARCH AND DEVELOPMENT
      U.S.  ENVIRONMENTAL PROTECTION AGENCY
            CINCINNATI, OHIO  45268

                      267

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                                  METHOD  245.5

                      DETERMINATION OF MERCURY  IN SEDIMENTS
                  BY COLD VAPOR ATOMIC ABSORPTION SPECTROMETRY
 1.    SCOPE AND APPLICATION

      1.1   This procedure1-2 measures total mercury (organic + inorganic)  in
           soils,  sediments,  bottom deposits and sludge type materials.

      1.2   The range of the method is  0.2  to 5 /zg/g.   The range may be
           extended  above or  below the normal  range by increasing  or decreasing
           sample  size or by  optimizing instrument sensitivity.

 2.    SUMMARY  OF METHOD

      2.1   A weighed portion  of  the sediment sample is  transferred  to  a BOD
           bottle  (or equivalent flask fitted  with a ground  glass stopper) and
           digested  in aqua regia for  2 min  at 95°C.   The digested  sediment
           sample  is diluted.  Potassium permanganate  is  added to the  sediment
           sample.   The  BOD bottle  is  transferred to the  water bath where the
           sediment  sample  is oxidized  for 30  min at 95°C.   Mercury in the
           digested  sediment  sample  is  reduced  with stannous chloride  to
           elemental  mercury  and  measured by the conventional cold vapor atomic
           absorption  technique.

     2.2  An alternate digestion3 involving the use  of an autoclave is
          described  in  (Sect. 11.3).

3.   DEFINITIONS

     3.1  BIOCHEMICAL OXYGEN DEMAND (BOD)  BOTTLE - BOD bottle,  300 ± 2 mL with
          a ground glass stopper or an equivalent flask, fitted with a ground
          glass stopper.

     3.2  CALIBRATION BLANK - A volume of  ASTM type  II reagent  water prepared
          in the same manner  (acidified) as the calibration standard.

          CALIBRATION STANDARD (CAL) - A solution prepared from the mercury
          stock standard solution used to  calibrate the instrument  response
          with respect to analyte concentration.

          INSTRUMENT DETECTION  LIMIT (IDL)  - The mercury concentration that
          produces a signal equal to three times the standard deviation of the
          blank signal.

          LABORATORY FORTIFIED BLANK (LFB)  - An aliquot of ASTM  type  II
          reagent  water to  which known quantities of inorganic and/or  organic
          mercury  are added in the  laboratory.   The LFB is analyzed  exactly
3.3
3.4
3.5
                                     268

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         like a sample, and its purpose is to determine whether method
         performance is within accepted control limits.

    3.6  LABORATORY FORTIFIED SAMPLE MATRIX (LFM) - An aliquot of a sediment
         sample to which known quantities of  calibration standard are added
         in the laboratory.  The LFM is analyzed exactly like a sample, and
         its purpose is to determine whether the sample matrix contributes
         bias to the analytical results.  The background concentrations of
         the analytes  in the sample matrix must be determined in a separate
         aliquot and the measured values in the LFM corrected for the
         concentrations found.

    3.7  LABORATORY REAGENT BLANK (LRB) - An aliquot of ASTM type II reagent
         water that is treated exactly as a sample including exposure to all
         glassware, equipment, and reagents used in analyses.  The LRB is
         used to determine if method analyte or other  interferences are
         present in the laboratory environment, reagents, or apparatus.

    3.8  LINEAR DYNAMIC RANGE  (LDR) - The concentration range over which the
         analytical working curve remains linear.

    3.9  METHOD DETECTION  LIMIT  (MDL) - The minimum concentration of mercury
         that can  be  identified, measured and  reported with 99% confidence
         that the  analyte  concentration is greater than zero and determined
         from analysis of  seven  LFMs.

    3.10 QUALITY CONTROL SAMPLE  (QCS) - A sediment sample containing  known
         concentration of  mercury derived from externally prepared test
         materials.   The QCS  is  obtained  from  a  source external to the
         laboratory  and  is used  to check  laboratory performance.

    3.11 SEDIMENT  SAMPLE - A  fluvial,  sand  and/or  humic  sample matrix  exposed
         to a marine,  brackish or fresh water  environment.   It  is  limited  by
         this method  to  that  portion which  may be  passed through  a number
          10 sieve  or  a 2 mm mesh sieve.

     3.12 STOCK  STANDARD  SOLUTION - A  concentrated  mercury  solution prepared
          in the laboratory using assayed  mercuric  chloride  or  stock  standard
          solution  purchased  from a  reputable  commercial  source.

4.   INTERFERENCES

     4.1  Interferences have  been reported for waters  containing  sulfide,
          chloride, copper and tellurium.   Organic  compounds which have broad
          band UV absorbance  (around  253.7 nm)  are  confirmed interferences.
          The concentration levels for interferants are difficult  to  define.
          This suggests that quality control  procedures (Sect.  10)  must be
          strictly followed.

     4.2  Volatile materials which absorb at 253.7  nm will  cause a positive
          interference.  In order to remove any interfering volatile


                                     269

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           materials,  the dead  air space  in  the  BOD  bottle  should  be  purged
           before  addition of stannous  chloride  solution.
5.   SAFETY

     5.1  The  toxicity  and  carcinogenicity of each reagent used  in this method
          has  not  been  fully established.  Each chemical should  be regarded  as
          a potential health hazard and exposure to these compounds should be
          minimized by  good laboratory practices4.  Normal  accepted
          laboratory safety practices should be followed during  reagent
          preparation and instrument operation.  Always wear safety glasses  or
          full-face shield for eye protection when working with  these
          reagents.  Each laboratory is responsible for maintaining a current
          safety plan,  a current awareness file of OSHA regulations regarding
          the  safe handling of the chemicals specified in this method * 6.

     5.2  Mercury compounds are highly toxic if swallowed,  inhaled, or
          absorbed through the skin.  Analyses should be conducted in a
          laboratory exhaust hood. The analyst should use chemical resistant
          gloves when handling concentrated mercury standards.

6.   APPARATUS AND EQUIPMENT

     6.1  ABSORPTION CELL - Standard spectrophotometer cells 10-cm long
          having quartz windows may be used.   Suitable cells may be
          constructed from plexiglass  tubing,  1-in.  O.D.  by 4 1/2-in.  long.
          The  ends are ground perpendicular to the longitudinal  axis  and
          quartz windows (1-in.  diameter by 1/16-in.  thickness)  are cemented
          in place.  Gas inlet  and outlet  ports  (also  of plexiglass but
          1/4-in.  O.D.)  are attached approximately 1/2-in.  from  each  end.   The
          cell  is  strapped to a burner for support and aligned  in the  light
          beam to  give the maximum transmittance.

     6.2  AERATION TUBING -  Inert  mercury-free tubing  is  used for passage  of
          mercury  vapor  from the sample  bottle to  the  absorption  cell    In
          some  systems,  mercury vapor  is recycled.  Straight glass tubing
          terminating  in a coarse  porous glass aspirator  is used  for purging
          mercury  released from the  sediment sample in the BOD bottle.

          AIR  PUMP  - Any pump (pressure or vacuum  system) capable of passing
          air  1 L/min  is used.  Regulated  compressed, air can be used in  an
          open  one-pass  system.

    6.4   ATOMIC ABSORPTION SPECTROPHOTOMETER - Any atomic absorption unit
          having an open sample presentation area in which to mount the
          absorption cell is suitable.   Instrument settings recommended by the
          particular manufacturer should be followed.   Instruments designed
          specifically for mercury measurement using the cold vapor technique
          are commercially available and may be substituted for the atomic
          absorption spectrophotometer.
6.3
    6.5  BIOCHEMICAL OXYGEN DEMAND (BOD) BOTTLE - See Sect.
                                                        3.1.
                                     270

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6.6  DRYING TUBE - Tube (6-in. x 3/4-in. OD) containing 20 g of magnesium
     perch!orate.  The filled tube is inserted (in-line) between the BOD
     bottle and the absorption tube.  In place of the magnesium
     perchlorate drying tube, a small reading lamp is positioned to
     radiate heat (about 10°C above ambient) on the absorption cell.
     Heat from the lamp prevents water condensation in the cell.

6.7  FLOWMETER - Capable of measuring an air flow of 1 L/min.

6.8  MERCURY HOLLOW CATHODE LAMP - Single element hollow cathode lamp or
     electrodeless discharge lamp and associated power supply.

6.9  PYREX DISH - Any appropriate size, (8-in. x 8-in.) or  (8-in. x 12-
     in.).

6.10 RECORDER - Any multi-range variable speed recorder that  is
     compatible with the UV detection system is suitable.

6.11 SIEVE -/High-density polyethylene; polyester mesh, no.  10 mesh,  12-
     in. Q.D and 3 1/2-in.; depth.

6.12 WATER BATH  - The water bath  should have a covered  top  and capacity
     to  sustain  a water depth of  2-in.  to 3-in. at 95°C ± 1°C. The
     dimensions  of the water  bath should be large enough  to accommodate
     BOD bottles containing CAL,  LFB, LFM,  LRB, QCS  and  sediment  samples
     With  the lid on.

REAGENTS AND CONSUMABLE MATERIALS

7.1  Reagents may contain elemental  impurities which bias analytical
     results.   All reagents  should  be assayed  by  the chemical
     manufacturer for  mercury'and meet  ACS  specifications.   It is
     recommended that  the laboratory analyst  assay all  reagents  for
     mercury.

     7.1.1     Hydrochloric  Acid  (HCL),  concentrated (sp.gr. 1.19),
                (CASRN  7647-01-0);  assayed mercury level  is not to exceed
                1 ppb.

      7.1.2     Hydroxylamine Hydrochloride  (NH.OH-HCl), (CASRN 5470-11-1)
                may  be  used  in place of hydroxylamine sulfate (Sect.  7.6);
                assayed mercury level of compound  is  not to exceed
                0.05  ppm.

      7.1.3     Hydroxylamine Sulfate [(NHgOHJ^H.SOJ  (CASRN 10039-54-0);
                assayed mercury level of compound  is  not to exceed
                0.05 ppm.

      7.1.4     Mercuric Chloride (HgCl2),  (CASRN  7487-94-7).
                                  271

-------
                       i     (HN°3)'  concentrated  (sp.gr.  1.41),  (CASRN
                     -37-2);  assayed mercury level  is  not  to exceed 1  ppb.

                 Potassium Permanganate  (KMnOJ, (CASRN 7722-64-7);  assayed
                 mercury level  is  not to exceed  0.05 ppm.

                 Reagent Water, ASTM type II.7

                 Sodium  Chloride (NaCl),  (CASRN  7647-14-5);  assayed mercury
                 level is  not to exceed  0.05 ppm.

                 Stannous  Chloride  (SnCl2'2H20),  (CASRN 10025-69-1);
                 assayed mercury level is  not to exceed 0.05  ppm.

                 Stannous  Sulfate  (SnS04), (CASRN 7488-55-3); assayed
                 mercury level is not to exceed 0.05 ppm.
      7.1.5


      7.1.6


      7.1.7

      7.1.8


      7.1.9


      7.1.10



      7'1'11     7ciru«ic Acid  (H2S04)> concentrated (sp.gr. 1.84), (CASRN
                7664-93-9);  assayed mercury  level  is  not  to exceed  1  ppb.

7.2  AQUA  REGIA - Prepare immediately before use  by  carefully  addina
     three volumes of cone. HC1  (Sect. 7.1.1) to  one volume of cone  HNO,
      (o6Ct. 7.1.5).                                                     •*

7.3  MERCURY CALIBRATION STANDARD - To each volumetric flask used for
     serial dilutions, acidify with  (0.1 to 0.2%  by  volume) HNO,
     (Sect. 7.1.5).  Using mercury stock standard (Sect. 7.4), make
     serial dilutions to obtain a concentration of 0.1 ug Hq/mL   This
     standard should be prepared just before analyses.

7-4  UEKr?Y STOCK STANDARD - Dissolve in a 100-mL volumetric flask
     0.1354 g HgCl,  (Sect.  7.1.4) with  75 mL of  reagent water  (Sect.
7'5
                                                   of
                                                             
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8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE

     8.1  Because of the extreme sensitivity of the analytical procedure and
          the presence of mercury in a laboratory environment, care must be
          taken to avoid extraneous contamination.  Sampling devices, sample
          containers, and plastic items should be determined to be free of
          mercury; the sample should not be exposed to any condition in the
          laboratory that may result in contamination from airborne mercury
          contamination.  All items used in the sample preparation should be
          soaked in 30% HNO, (Sect.  7.1.5)  and rinsed three times in reagent
          water (Sect. 7.1.7).

     8.2  The sediment sample should be preserved with nitric acid to an
          approximate pH of  2.

     8.3  Slowly decant the  water from the settled sediment sample.  Transfer
          the sediment sample into  a Pyrex tray and mix thoroughly with a
          Teflon spatula.  Discard  sticks, stones, shells, living or dead
          tissues  and  other  foreign objects from  the  sediment sample.

     8.4  Transfer the sediment  from the Pyrex tray to a  10-mesh
           (approximately 2-mm)  sieve collecting the sediment  sample  in  an
           appropriate  container.  If enough sample has been collected,  a
           second container may  be used for the percent wet weight
           determination.

     8.5   While  the  sample may  be analyzed without drying,  it has  been  found
           to be  more convenient to  analyze  a  dry  sample.   Moisture  may  be
           driven  off in  a drying oven  at a  temperature of 60°C.   No mercury
           losses  have been  observed by using  this drying  step.   The dry sample
           should be  pulverized  and  thoroughly mixed  before the  aliquot  is
           weighed.

 9.    CALIBRATION AND STANDARDIZATION

      9.1   Transfer 0.5,  1.0, 2.0,  5.0  and  10  ml aliquots  of the 0.1 jug/mL CAL
           (Sect.  7.3) to a  series  of 300-mL BOD bottles.   These BOD bottles
           will  contain 0.5  to 1.0  /zg of Hg and are used to calibrate the
           instrument.

      9.2  To each of the BOD bottles add enough reagent  water (Sect. 7.1.7) to
           make a total volume of 10 ml.   Add 5 mL of aqua regia (Sect.  7.2)
           immediately cap and cover the top of the BOD bottle with aluminum
           foil  or other appropriate cover.

      9.3  Construct a standard curve by plotting peak height or maximum
           response of the standards (obtained in Sect. 11.7) versus micrograms
           of mercury contained in  the bottles.  The standard curve should
           comply with Sect. 10.2.3.  Calibration using computer or calculator
           based regression  curve fitting techniques on concentration/response
           data is acceptable.


                                       273

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 10.2.2
10.  QUALITY CONTROL


     10>1 S-labora+°7 /n^9 this method is  ™Wired  to  operate  a  formal
          quality control  (QC)  program.   The minimum requirements of  this
          program consist of an initial  demonstration of laboratory capa-
          bility by analyses of laboratory reagent  blanks,  fortified  blanks
          and samples  used for  continuing check on  method performance.
          Standard Reference Materials  (SRMs)8-  9- 10 are  available  and
          should be used  to validate laboratory performance.  Commercially
          available sediment reference materials are acceptable for routine
          vTn£!  !3[ SSS'*.^laboratory is  required to  maintain   performance
          records  that define the quality of  the data generated.

     10.2  INITIAL  DEMONSTRATION  OF PERFORMANCE.

          10.2.1     The initial  demonstration of performance is used to
                    characterize instrument performance  (MDLs and linear
                    calibration  ranges) for analyses  conducted by this method.

                   A mercury MDL should  be established using LFM at a
                   concentration of two  to five times the estimated detection
                   limit  .   To  determine MDL values,  take  seven replicate
                   aliquots of the LFM and process through  the entire
                   analytical method.  Perform all  calculations defined in
                   the method and report the concentration  values  in  the
                   appropriate units.  Calculate the MDL as follows:

                   MDL = (t) x (S)

                   where:  t = Student's  t value for a 99% confidence  level
                              and  a  standard deviation estimate with  n-1
                              degrees  of freedom  is, t  = 3.14  for  seven
                              replicates.

                           S =  standard  deviation of the replicate  analyses.

                   A MDL  should  be determined every six  months  or whenever a
                   significant  change in  background or instrument response is
                   expected (e.g., detector change).

                   Linear  calibration ranges  -  The  upper  limit of the linear
                   calibration range  should be  established  for mercury by
                   determining the signal  responses  from  a minimum  of three
                   different  concentration  standards,  one of which  is close
                   to the  upper  limit of  the  linear  range.  Linear
                   calibration ranges should  be determined every six months
                   or whenever a significant change  in instrument response is
                   observed.

   10.3 ASSESSING  LABORATORY PERFORMANCE - REAGENT AND FORTIFIED BLANKS
10.2.3
                           274

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    10.3.1    The laboratory must analyze at least one LRB (Sect.  3.7)
              with each set of samples.   LRB data are used to assess
              contamination from the laboratory environment and to
              characterize spectral background from the reagents used in
              sample processing.  If a mercury value in a LRB exceeds
              its determined MDL, then laboratory or reagent
              contamination is suspect.   Any determined source of
              contamination should be eliminated and the samples
              reanalyzed.

    10.3.2    The laboratory must analyze at least one LFB (Sect. 3.5)
              with each batch of samples.  Calculate accuracy as percent
              recovery (Sect. 10.4.2).  If recovery of mercury falls
              outside control limits (Sect. 10.3.3), the method is
              judged out of control.  The source of the problem should
              be  identified and resolved before continuing analyses.

    10.3.3    Until sufficient data  (usually a minimum of 20 to 30
              analyses) become available, each laboratory should assess
              its performance against recovery limits of 85-115%.  When
              sufficient  internal  performance data become available,
              develop  control limits from the percent mean recovery  (x)
              and the  standard deviation  (S) of the mean recovery.
              These data  are  used  to establish upper  and lower control
              limits as  follows:

                  UPPER CONTROL  LIMIT =  x  +  3S
                  LOWER CONTROL  LIMIT =  x  -  3S

              After each five to ten new  recovery measurements,  new
              control  limits  should be  calculated using  only the  most
              recent  20  to 30 data points.

10.4 ASSESSING ANALYTE  RECOVERY  - LABORATORY FORTIFIED SAMPLE MATRIX

     10.4.1   The laboratory must add  a known amount of mercury to a
              minimum of 10% of samples or one sample per sample set,
              whichever is greater.  Select a sediment sample that is
               representative of the type of sediment being analyzed and
               has a low mercury background.  It is recommended that this
               sample be analyzed prior to fortification.  The
               fortification should be 20% to 50% higher than the
               analyzed value.  Over time, samples from all  routine
               sample sources should be fortified.

     10.4.2    Calculate the percent recovery, corrected for background
               concentrations measured in the unfortified sample, and
               compare these values to the control limits established in
               Sect. 10.3.3 for the analyses of LFBs.  A recovery
               calculation is not required if the concentration of the
               analyte added  is less than 10% of the sample background
               concentration.  Percent recovery may be calculated in

                                 275

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                     units appropriate to the matrix,  using  the  following
                     equation:                                           3
                     R
                         CS-C
            x  100
                    where,  R

                            I-
                            s
            percent recovery
            fortified sample concentration
            sample background concentration
            concentration equivalent of
            fortifier added to sediment sample,
          10.4.3
If mercury recovery falls outside the designated range,
and the laboratory performance is shown to be in control
(beet. 10.3)  the recovery problem encountered with the
fortified sediment sample is judged to be matrix related,
not system related.  The result for mercury in the
unfortified sample must be labelled to inform the data
user that the results are suspect due to matrix effects
11.  PROCEDURE
                               °f dry sample and Place in  bo«om of a BOD
                (Sect  7           ^ Water (56Ct'  7'L7)  and  5 mL of aa.ua
          hntti    -JI*  I'2)  ! """^lately cap  and  cover  the  top of the BOD
          bottle with aluminum foil  or other appropriate cover.   Optionally  a
          s^v^tTAh033!? t0 3'4  9 ma£  be Used to adJust  ^e  respon e  to
          stay within the  linear range of  the standards.

     11.2  Mix  thoroughly,  and  place  in the water bath  for 2  min  at  95<>C.

     11.3  Remove the  BOD bottles  and  allow to cool.  Add 50  ml reagent water

                          1
                                                      are
                                                      are
                                          emP1oyin9 an autoclave may also be
         cone' Him  rrt  7i          L0n,C' H2S04 (Sect"  7-1-11>  and 2 «"- °
         cone. HN03 (Sect.  7.1.5)  are added  to 0.2 g sediment  sample.   Then
         BoS hnLSat"rated P;ta??,lum Permanganate solution is  added and the
         BOD bottle is capped with a piece of aluminum foil.   The samples a
         then autoclaved at 121-C/15 psi. for 15 min.             samples a

    11.4 Turn on the spectrophotometer and circulating pump.   Adiust the

                 ?0 1 L/min'   A11°W the sPect™Photomete? and pump to


                  B°D b°UleS t0 r°°m temPerature and dilute in the following
                                    276

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         11.5.1    To BOD bottles containing the instrument calibration
                   standards laboratory fortified blank (LFB)  and laboratory
                   reagent blank (LRB) add 50 ml of reagent water
                   (Sect. 7.1.7).

         11.5.2    To BOD bottles containing the sediment samples, quality
                   control sample (QCS) and laboratory fortified sample
                   matrix (LFM) add 55 ml of reagent water (Sect. 7.1.7).

    11.6 To each BOD bottle, add 6 ml of NaCl-(NH2OH)2'H2S04 (Sect.  7.6)  to
         reduce the excess permanganate.

    11.7 Treating each bottle  individually:

         11.7.1    Placing the aspirator inside the BOD bottle and above the
                   liquid, purge the head space (20 to 30 sec) to remove
                   possible gaseous interferents.

         11.7.2    Add 5  ml of SnCl2 solution (Sect. 7.7) and immediately
                   attach the  bottle to the aeration apparatus.

         11.7.3    The absorbance, as exhibited either on the
                   spectrophotometer or the recorder, will increase and  reach
                   maximum within 30 sec.  As soon  as the recorder pen levels
                   off,  approximately  1 min, open the bypass value (or
                   optionally  remove aspirator  from the  BOD bottle if  it is
                   vented under  the hood) and continue the aeration until the
                   absorbance  returns  to  its minimum value.

     11.8 Close the bypass value,  remove the  aspirator from the  BOD bottle and
         continue the  aeration.   Repeat step  (Sect. 11.7)  until  all BOD
         bottles have  been  aerated and  recorded.

12.   CALCULATIONS

     12.1 Measure the peak height of the unknown from the chart  and read  the
         mercury value from the  standard  curve.

     12.2 Calculate  the mercury concentration in the sample by  the formula:

                    ir  I   -      V-9 H& i-n the aliquot
                    ng/g -
                                  Qf  the a2iqu0t  in grams
     12.3 Report mercury concentrations as follows:   Below 0.1 Mg/9.
          < 0.1 Mg/g; between 0.1 and 1 ng/g, to the nearest 0.01 pg; between
          1 and 10 M9/9, to nearest 0.1 M9;  above 10 jug/g,  to  nearest M9-
                                      277

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13.  PRECISION AND ACCURACY

     13.1 The standard deviation for mercury in sediment samples are reported
          mi h«?   S™  ^ 5^g a"d 0.82 ± 0.03 jig Hg/g with recoveries for
          LFM being 97% and 94% respectively.  These sediment samples were
          fortified with methyl mercuric chloride.

          Hu^lirLassurance data for the sediment survey was contributed by
          U.S. EPA, Environmental Research Laboratory - Duluth.   See Table 1.
    9.
10.
14.  REFERENCES
     2.



     3.


     4.



     5.



     6.



     7.


    8.
                                             "'  °ntari° water
      Glass, G.E.; Sorensen, J.A.; Schmidt, K.W.; Rapp Jr., G.R.; "New
      Source Identification of Mercury Contamination in the Great Lakes"
      Envion. Sci. and Techno!.. Vol. 24, No. 7, 1990.                  '

      Salma, M., private communication,  EPA Cal/Nev Basin Office, Almeda,
      California.                                                       '

      "Safety in Academic Chemistry Laboratories",  American Chemical
      1979    Publlcatlon'  Committee on  Chemical Safety,  3rd Edition,


      "OSHA Safety and Health  Standards,  General Industry",  (29CFR 1910)
      Occupational  Safety and  Health Administration,  OSHA 2206,  revised
      January,  1976.

      "Proposed  OSHA  Safety and  Health Standards, Laboratories"
      Occupational^Safety and  Health Administration,  Federal  Register,


      "Specification  for  Reagent Water",  D1193,  Annual Book  of ASTM
      Standards,  Vol.  11.01, 1990.

      National Institute  of Standards and Technology, Office of Standards
      VIST?£^  aT6rialr;  Gaithel"sburg, MD 20899:  Estuarine Sediment
      (SRM 1646), Trace Elements in  a Calcerous  Loam Soil  (CRM 8032),

     IS SS:!^.!:!!^8^^!.!?1?,???3). T«« El-ents in
                                                      in Sewer Sludge-
                                                       12201
         National  Research  Council  of Canada,  Marine  Analytical  Chemistry
         Standards Program,  Division  of Chemistry,  Montreal  Road,  Ottawa
         Ontario K1A OR9,. Canada:   Marine  Sediments (BCSS-1,  MESS-1,  and
         rALb—l ) .
    11.  Code  of  Federal  Regulations 40, Ch.  1,  Pt.  136 Appendix  B.
                                    278

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        TABLE 1.   QUALITY ASSURANCE SUMMARY FOR 15 SEDIMENT ANALYSES
             IQfift SURVEY OF MINNESOTA LAKES1' z.
                                             Number of Samples or
   Parameter	          Value            Sample Pairs	
Detection Limit in Flask3
     (ng Hg/L)                   6.6                   471

Precision (ng Hg/L)
Lab
Field
Bias (%)
Spike Recovery (%)
Loss on Drying (%)
27
26
-2
100 + 7
5.3 + 1.0
29
96
30
27
72
      1 Data were  furnished  by  Gary  Glass,  U.S.  EPA,  Environmental  Research
 Laboratory -  Duluth,  Minnesota 55804,  and John A.  Sorensen,  College of Science
 and Engineering,  University of Minnesota, Duluth,  Minnesota   55812.

      2 The analytical  instrument  used  to  achieve the precision  and accuracy
 included:   Perkin Elmer atomic absorption spectrophotometers (Model 403 and
 5000) equipped with deuterium background correctors, electrodeless discharge
 lamp (ME-782) and power supply (APR),  and Heath Schlumberger (SR-206) chart
 recorder.   A slit width of 1 mm (spectral band with 0.07 nm) was used at a
 wavelength of 253.7 nm.  The instruments were operated in the concentration
 mode (10 x) with the integration set at 10 average  (ten samples of the signal
 are averaged as one value per second).  The concentration readout of the
 signal  was recorded on the strip chart at 20 mv/25 cm chart width.  The
 elemental  mercury analyte was circulated  (1 L/min) through a (18 x 1.8 cm)
 cylindrical absorption cell using a Neptune Dyna Pump.  After the atomic
 absorption resulting from the presence of mercury vapor reached a maximum  in
 about 0.5-1.0 min, the pump was turned off and the  absorption peak climbed to
 its final  value.

      3 Long,  G.L.; Winefordner, J.D.;  Anal. Chem.  1983, Vol. 55: 712A-724A.

                                       279

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                  BUBBLER
      SAMPLE  SOLUTION
      IN BOO  BOTTLE
ABSORPTION
    CELL
SCRUBBER
CONTAINING
A MERCURY
ABSORBING
MEDIA
         Flgurt 1.  Apparatus for Flaneless Mercury Determination
Because of the toxic nature of mercury vapor, inhalation must be avoided.
SS3 ?£?'  a byEa" hp been Included in the system to  either vent the mercury
vapor into  a exhaust hood or pass the vapor through some absorbing media, such
as:    a) equal volumes of 0.1 N KMnO, and 10% H,S P<°' B°X 2526> Columbus«  OH   «216.  Catalog No! 580-
                                  280

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                 METHOD 245.6

     DETERMINATION OF MERCURY IN TISSUES
 BY COLD VAPOR ATOMIC ABSORPTION SPECTROMETRY
Edited by Larry B. Lobring and Billy B. Potter
          Inorganic Chemistry Branch
          Chemistry Research  Division
                 Revision 2.3
                  April  1991
  ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
       OFFICE  OF  RESEARCH  AND  DEVELOPMENT
      U.S.  ENVIRONMENTAL PROTECTION AGENCY
            CINCINNATI, OHIO  45268

                      281

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                             METHOD 245.6

                  DETERMINATION OF MERCURY IN  TISSUES
             BY COLD VAPOR ATOMIC ABSORPTION SPECTROMETRY
 SCOPE AND APPLICATION

 1.1  This procedure measures total mercury (organic + inorganic) in
      biological tissue samples.

 1.2  The range of the method is 0.2 to 5 /ug/g.  The range may be extend-
      ed above or below the normal  range by increasing or decreasing
      sample size or by optimizing  instrument sensitivity.

 SUMMARY OF METHOD
 2.1
 A weighed portion of the tissue sample  is  digested  with  sulfuric  and
 nitric acid at 58°C followed by overnight  oxidation with potassium
 permanganate and potassium persulfate at room temperature.   Mercury
 in the digested sample  is reduced  with  stannous  chloride to
 elemental  mercury and measured  by  the conventional  cold  vapor  atomic
 absorption technique.
 DEFINITIONS
 3.1
3.2
3.3
3.4
3.5
3.6
 BIOCHEMICAL  OXYGEN  DEMAND  (BOD)  BOTTLE -  BOD  bottle, 300 ± 2 mL with
 a ground glass  stopper or  an equivalent flask, fitted with a ground
 glass stopper.

 CALIBRATION  BLANK - A volume of  ASTM type II  reagent water prepared
 in the same  manner  (acidified) as the calibration standard.

 CALIBRATION  STANDARD (CAL) - A solution prepared from the mercury
 stock standard  solution used to  calibrate the instrument response
 with respect to analyte concentration.

 INSTRUMENT DETECTION LIMIT (IDL) - The mercury concentration that
 produces a signal equal to three times the standard deviation of the
 blank signal.

 LABORATORY FORTIFIED BLANK (LFB) - An aliquot of ASTM type II
reagent water to which known quantities of inorganic and/or organic
mercury are added in the laboratory.  The LFB is analyzed exactly
like a sample, and its purpose is to determine whether method
performance is within accepted control  limits.

LABORATORY FORTIFIED SAMPLE MATRIX (LFM)  - A portion of a tissue
sample to which known quantities of  calibration standard are added
in the laboratory.   The LFM is analyzed exactly like a sample,  and
its purpose is to determine whether the sample matrix contributes
                                282

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         bias to the analytical results.  The background concentrations of
         the analytes in the sample matrix must be determined in a separate
         aliquot and the measured values in the LFM corrected for the
         concentrations found.

    3.7  LABORATORY REAGENT BLANK (LRB) - An aliquot of ASTM type II reagent
         water that is treated exactly as a sample including exposure to all
         glassware, equipment, and reagents used in analyses.  The LRB is
         used to determine if method analyte or other interferences are
         present in the laboratory environment, the reagents or apparatus.

    3.8  LINEAR DYNAMIC RANGE  (LDR) - The concentration range over which the
         analytical working curve remains linear.

    3.9  METHOD DETECTION LIMIT  (MDL) - The minimum concentration of mercury
         that can  be  identified, measured and reported with 99% confidence
         that the  analyte concentration is greater than zero and determined
         from analysis of laboratory fortified tissue sample matrix  (LFM).

    3.10 QUALITY CONTROL SAMPLE  (QCS) - A tissue sample containing known
         concentration of mercury derived from externally  prepared test
         materials.   The QCS  is  obtained from a source external to the
         laboratory  and  is used  to check laboratory performance.

    3.11 TISSUE  SAMPLE - A biological  sample matrix exposed to  a marine,
         brackish  or fresh water environment.   It  is  limited by this method
         to the  edible tissue portion.

     3.12 STOCK  STANDARD  SOLUTION - A concentrated  solution containing  mercury
         prepared  in the laboratory  using  assayed  mercuric chloride  or stock
          standard  solution  purchased from  a  reputable commercial  source.

4.   INTERFERENCES

     4.1  Interferences have  been reported  for  waters  containing sulfide,
          chloride, copper and tellurium.   Organic  compounds which  have broad
          band UV absorbance  (around  253.7  nm)  are  confirmed interferences.
          The concentration levels for interferants are difficult  to  define.
          This suggests that quality control  procedures (Sect.  10)  must be
          strictly followed.

     4.2  Volatile materials which absorb at 253.7  nm will  cause a positive
          interference.  In order to remove any interfering volatile
          materials, the dead air space in the BOD bottle should be purged
          before the addition of stannous chloride solution.

     4.3  Interferences associated with the tissue matrix are corrected for in
          calibration procedure  (Sect. 9).
                                      283

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      SAFETY
      5.1
     5.2
     5.3
 The toxicity and carcinogenicity of each reagent used in this method
 has not been fully established.  Each chemical should be regarded as
 a potential health hazard and exposure to these compounds should be
 minimized by good laboratory practices1.   Normal  accepted
 laboratory safety practices should be followed during reagent
 preparation and instrument operation.  Always wear safety glasses or
 full-face shield for eye protection when working with these
 reagents.  Each laboratory is responsible for maintaining a current
 safety plan, a current awareness file of OSHA regulations regarding
 the safe handling of the chemicals specified in this method ?' 3.

 Mercury compounds are highly toxic if swallowed,  inhaled, or
 absorbed through the skin.  Analyses should be conducted in a
 laboratory exhaust hood. The analyst should use chemical resistant
 gloves when handling concentrated mercury standards.

 All  personnel  handling tissue samples should beware of biological
 hazards associated with tissue samples.   Bivalve  mollusk may
 concentrate toxins and pathogenic organisms.  Tissue  dissection
 should be conducted in a bio-hazard hood  and personnel  should wear
 surgical  mask  and gloves.
6.   APPARATUS AND EQUIPMENT
     6.1
     6.2
     6.3
     6.4
ABSORPTION  CELL  -  Standard  spectrophotometer  cells  10-cm  long,
having  quartz  windows may be  used.   Suitable  cells  may  be
constructed from plexiglass tubing,  1-in. O.D.  by 4-1/2-in.  long.
The  ends  are ground  perpendicular to the  longitudinal axis  and
quartz  windows (1-in. diameter  by 1/16-in. thickness) are cemented
in place.   Gas inlet and outlet ports  (also of  plexiglass but 1/4-
in.  O.D.) are  attached  approximately 1/2-in.  from each  end.  The
cell  is strapped to  a burner  for support  and  aligned in the  light
beam to give the maximum transmittance.

AERATION TUBING  -  Inert mercury-free tubing is  used for passage of
mercury vapor  from the  sample bottle to the absorption  cell.  In
some  systems,  mercury vapor is  recycled.  Straight glass  tubing
terminating  in a coarse porous  glass aspirator  is used  for purging
mercury released from the tissue sample in the  BOD bottle.

AIR  PUMP - Any pump  (pressure or vacuum system) capable of passing
air  at  1 L/min is used.  Regulated compressed air can be  used in an
open one-pass  system.

ATOMIC ABSORPTION SPECTROPHOTOMETER - Any atomic absorption unit
having  an open sample presentation area in which to mount the
absorption cell  is suitable.  Instrument settings recommended by the
particular manufacturer should be followed.   Instruments designed
specifically for mercury measurement using the cold vapor technique
                                     284

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     are commercially available and may be substituted for the atomic
     absorption spectrophotometer.

6.5  BIOCHEMICAL OXYGEN DEMAND (BOD) BOTTLE - See Sect. 3.1.

6.6  DRYING TUBE - Tube (6-in. x 3/4-in. OD) containing 20 g of magnesium
     perchlorate.  The filled tube is inserted (in-line) between the BOD
     bottle and the absorption tube.  In place of the magnesium
     perchlorate drying tube, a small reading lamp is positioned to
     radiate heat (about 10°C above ambient) on the absorption cell.
     This avoids water condensation in the cell.

6.7  FLOWMETER - Capable of measuring an air flow of 1 L/min.

6.8  MERCURY HOLLOW CATHODE LAMP - Single element hollow cathode lamp or
     electrodeless discharge lamp and associated power supply.

6.9  RECORDER - Any multi-range variable speed recorder that is
     compatible with the UV detection system is suitable.

6.10 WATER BATH - The water bath should have a covered top and capacity
     to sustain a water depth of 2-in. to 3-in. at 95°C ± 1°C.  The
     dimensions of the water bath should be large enough to accommodate
     BOD bottles containing CAL, LFB, LFM, LRB, QCS and tissue samples
     with the lid on.

REAGENTS AND CONSUMABLE MATERIALS

7.1  Reagents may contain elemental  impurities which bias analytical
     results.  All reagents should  be assayed by the chemical
     manufacturer for mercury and meet ACS specifications.

     7.1.1     Hydroxylamine Hydrochloride  (NHpOH'HCl), (CASRN 5470-11-1)
               may be used  in place  of hydroxyI amine sulfate in Sect.
               7.6.  The assayed mercury level of either compound  is not
               to exceed 0.05 ppm.

     7.1.2     Hydroxylamine Sulfate  [(NH2OH)2'H2S04] (CASRN 10039-54-0);
               assayed mercury level  is not to exceed  1 ppb.

     7.1.3     Mercuric Chloride  (HgCl2), (CASRN 7487-94-7).

     7.1.4     Nitric Acid  (HN03), concentrated (sp.gr. 1.41), (CASRN
               7697-37-2);  assayed  mercury level  is not to  exceed  1  ppb.

     7.1.5     Potassium Permanganate (KMn04), (CASRN  7722-64-7);  assayed
               mercury level  is not to  exceed  0.05  ppm.

     7.1.6     Potassium Persulfate (K2S208),  (CASRN 7727-21-1);  assayed
               mercury level  is not to  exceed  0.05  ppm.

     7.1.7     Reagent Water, ASTM  type  II.4

                                 285

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      7.1.8
      7.1.9
      7.1.10
      7.1.11
                     Sodium Chloride (NaCl), (CASRN 7647-14-5); assayed mercury
                     level is not to exceed 0.05 ppm.

                     Stannous Chloride (SnCl2'2H20),  (CASRN 10025-69-1);
                     assayed mercury level is not to exceed 0.05 ppm.

                     Stannous Sulfate (SnSOJ,  (CASRN 7488-55-3);  assayed
                     mercury level is not to exceed 0.05 ppm.

                     Sulfuric Acid (H2S04), concentrated  (sp.gr. 1.84),  (CASRN
                     7664-93-9); assayed mercury level is not to exceed 1 ppb.

      7.2  MERCURY CALIBRATION STANDARD - To each volumetric flask used for
           serial  dilutions,  acidify with (0.1  to 0.2% by volume)  HNO,
           (Sect.  7.1.4).   Using mercury stock  standard (Sect.  7.3), make
           serial  dilutions to obtain a concentration of 0.1  /ig Hg/mL.  This
           standard should be prepared just before analyses.

      7.3  MERCURY STOCK STANDARD -  Dissolve  in a 100-mL volumetric flask
           0.1354  g HgCl2  (Sect.  7.1.3) with 75 mL of reagent water
           (Sect.  7.1.7).   Add 10 ml of cone. HNO, (Sect.  7.1.4) and dilute  to
           mark.   Concentration  is 1.0 mg Hg/mL.

      7.4  POTASSIUM PERMANGANATE SOLUTION - Dissolve 5 g of  KMnO,
           (Sect.  7.1.5) in 100  mL of reagent water  (Sect.  7.1.7)!

      7.5  POTASSIUM PERSULFATE  SOLUTION  - Dissolve  5 g of K,S,0« (Sect.  7 1  6)
           in  100  mL of  reagent  water (Sect. 7.1.7).

      7.6  SODIUM  CHLORIDE-HYDROXYLAMINE  SULFATE  SOLUTION - Dissolve 12  g  of
           NaCl (Sect. 7.1.8)  and 12  g  of (NH,OH)2-H,SO, (Sect. 7.1.2) or 12 q
           of  NH-.OH-HC1  (Sect. 7.1.1) dilute with reagent water (Sect. 7.1.7)
           to  100  mL.

      7.7  STANNOUS  CHLORIDE  SOLUTION - Add 25 g  SnCl2'2H?0 (Sect.  7.1 9)  or
           25  g of SnS04 to 250 mL of 0.5 N H,SOA  (Sect.  7.8).   This mixture  is
           a suspension and should be stirrecf continuously during use.

      7.8   SULFURIC  ACID, 0.5 N  - Slowly  add 14.0 mL  of cone. H,SO,
           (Sect.   7.1.10) dilute  to 1 L with reagent water  (Sect. 7.1.7).

8.   SAMPLE COLLECTION. PRESERVATION AND STORAGE
8.1
          Because of the extreme sensitivity of the analytical procedure and
          the presence of mercury in a laboratory environment, care must be
          taken to avoid extraneous contamination.  Sampling devices, sample
          containers and plastic items should be determined to be free of
          mercury; the sample should not be exposed to any condition in the
          laboratory that may result in contact or airborne mercury
          contamination.
                                 286

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     8.2  The tissue sample should be preserved and dissected in accordance
          with Method 200.3,  "Sample Preparation Procedure for Spectrochemical
          Determination of Total  Recoverable Elements in Biological  Tissues",
          only Sect. 8. Tissue Dissection,  is used in this method.

     8.3  Weigh 0.2- to 0.3-g portions of each sample and place in  the bottom
          of a dry BOD bottle.  Care must be taken that none of the sample
          adheres to the side of the bottle.  Immediately cap and cover the
          top of the BOD bottle with aluminum foil.

9.   CALIBRATION AND STANDARDIZATION

     9.1  The calibration curve is prepared from values determined for
          portions of fortified tissue treated in the manner used for the
          tissue samples being analyzed.  For preparation of the calibration
          standards, blend a portion of tissue in a Waring blender.

     9.2  Transfer accurately weighed portions to each of five dry BOD
          bottles.  Each sample should weigh about 0.2 g.  Add 4 ml of cone.
          H2SO,  and  1  ml of cone.  HN03 to each bottle and place  in a water
          bath maintained at 58°C until the tissue is completely dissolved (30
          to 60 minutes).

     9.3  Cool and transfer 0.5, 2.0, 5.0 and 10.0 ml aliquots of the CAL
          (Sect. 7.2)  solution containing 0.5 to  1.0 p.g  of Hg to the  BOD
          bottles containing tissue.  Cool to 4°C in an  ice bath and
          cautiously  add 15 ml of potassium permanganate solution (Sect. 7.4)
          and 8 ml of  potassium persulfate  (Sect. 7.5).  Allow to stand
          overnight at  room temperature under oxidizing  conditions.

     9.4  Construct a  standard curve by plotting  peak height or maximum
          response of  the  standard  (obtained  in Sect. 11.7) versus micrograms
          of mercury  contained in the bottles. The standard curve should
          comply with  Sect. 10.2.3.  Calibration  using computer or calculator
          based regression curve fitting techniques  on concentration/response
          data  is acceptable.

 10.  QUALITY CONTROL

     10.1 Each  laboratory  using this method  is  required  to operate a  formal
          quality control  (QC) program.  The  minimum requirements of  this
          program consist  of  an initial demonstration of laboratory capability
          by  analyses of laboratory reagent  blanks,  fortified blanks  and
          samples used for continuing check  on  method performance.  Standard
          Reference  Materials  (SRMs)5'   are available  and should be used  to
          validate  laboratory performance.   Commercially available tissue
          reference materials  are  acceptable  for  routine laboratory use.   The
          laboratory is required  to maintain   performance  records that define
          the  quality of data generated.
                                      287

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 10.2  INITIAL DEMONSTRATION OF  PERFORMANCE

      10.2.1    The  initial demonstration of performance  is used to
               characterize  instrument performance  (MDLs and linear
               calibration ranges) for analyses conducted by this method.

      10.2.2    A mercury MDL should be established  using LFM at a
               concentration of two to five times the estimated detection
               limit'.  To determine MDL values, take seven replicate
               aliquots of the LFM and process through the entire
               analytical method.  Perform all calculations defined in
               the method and report the concentration values in the
               appropriate units.  Calculate the MDL as follows:

               MDL =  (t) x (S)

               where, t =  Student's t value for a 99% confidence level
                           and a standard deviation estimate with n-1
                           degrees of freedom [t = 3.14 for seven
                           replicates],

                      S =  standard deviation of the replicate analyses.

               A MDL should be determined every six months or whenever a
               significant change in background or instrument response is
               expected (e.g.,  detector change).

     10.2.3    Linear calibration ranges - The upper limit of the linear
               calibration range should be established for mercury by
               determining the signal  responses from a minimum of three
               different concentration standards,  one of which is close
               to the upper limit of the linear range.  Linear calibration
               ranges should be determined every six months or whenever a
               significant change in instrument response is observed.

10.3 ASSESSING LABORATORY PERFORMANCE  - REAGENT AND FORTIFIED BLANKS

     10.3.1    The laboratory must analyze at  least one LRB (Sect.  3.7)
               with each set of samples.   LRB  data are  used to assess
               contamination from the  laboratory environment  and to
               characterize spectral background from the reagents used in
               sample processing.   If  an  mercury value  in a LRB exceeds
               its determined MDL,  then laboratory or reagent
               contamination is suspect.   Any  determined source of
               contamination should be corrected and the samples
               reanalyzed.

     10.3.2    The laboratory must  analyze  at  least  one LFB (Sect.  3.5)
               with each batch  of samples.  Calculate accuracy as  percent
               recovery (Sect.  10.4.2).   If the  recovery of mercury falls
               outside control  limits  (Sect. 10.3.3), the method is
                                288

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               judged out of control.   The source of the problem should
               be identified and resolved before continuing analyses.

     10.3.3    Until  sufficient data (usually a minimum of 20 to 30
               analyses)  become available, each laboratory should assess
               its performance against recovery limits of 85-115%.   When
               sufficient internal  performance data become available,
               develop control limits  from the percent mean recovery (x)
               and the standard deviation (S) of the mean recovery.
               These  data are used  to  establish upper and lower control
               limits as  follows:

                  UPPER CONTROL LIMIT  = x + 3S
                  LOWER CONTROL LIMIT  = x - 3S

               After  each five to ten  new recovery measurements, new
               control limits should be calculated using only the most
               recent 20  to 30 data points.

10.4 ASSESSING ANALYTE RECOVERY - LABORATORY FORTIFIED SAMPLE MATRIX

     10.4.1    The laboratory must  add a known amount of mercury to a
               minimum of 10% of samples or one sample per sample set,
               whichever  is greater.  Select a tissue sample that is
               representative of the type of tissue being analyzed and
               has a  low  mercury background.  It is recommended that this
               sample be  analyzed prior to fortification.  The
               fortification should be 20% to 50% higher than the
               analyzed value.  Over time, samples from all routine
               sample sources should be fortified.

     10.4.2    Calculate  the percent recovery, corrected for background
               concentrations measured in the unfortified sample, and
               compare these values to the control limits established in
               Sect.  10.3.3 for the analyses of LFBs.  A recovery
               calculation is not required if the concentration of the
               analyte added is less than 10% of the sample background
               concentration.  Percent recovery may be calculated in
               units  appropriate to the matrix, using the following
               equation:

                   Cs - C
               R = 	  x 100
               where, R  = percent recovery
                      Cs = fortified  sample concentration
                      C  = sample background concentration
                      s  = concentration equivalent of
                           fortifier added to tissue sample.
                                289

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          10.4.3
 If mercury recovery falls outside the designated range,
 and the laboratory performance is shown to be in control
 (Sect. 10.3), the recovery problem encountered with the
 fortified tissue sample is judged to be matrix related,
 not system related.  The result for mercury in the
 unfortified sample must be labelled to inform the data
 user that the results are suspect due to matrix effects.
11.   PROCEDURE
     11.1 Add 4 ml of cone. H2SO,  (Sect. 7.1.10) and 1 mL of cone. HNO,
          (Sect. 7.1.4) to each Tpottle and place in a  water bath maintained at
          58°C until  the tissue is completely dissolved (30 to 60 min).

     11.2 Cool to 4°C in an ice bath and cautiously add 5 ml of potassium
          permanganate solution (Sect. 7.4)  in 1 ml increments.  Add an
          additional  10 ml or more of permanganate, as necessary to  maintain
          oxidizing conditions.  Add 8 mL  of potassium persulfate solution
          (Sect. 7.5).  Allow to stand overnight at room temperature.

          As  an alternative to the overnight digestion,  tissue solubilization
          may be carried out in a water bath at 80°C for 30 min.   The  sample
          is  cooled and 15 mL of potassium permanganate solution (Sect.  7.4)
          added cautiously followed by 8 mL  of potassium persulfate  solution
          (Sect. 7.5).  At this point, the sample  is returned  to the water
          bath and digested for an additional  90 min at 30°C.   Calibration
          standards are treated in the same  manner.

     11.3 Turn on the spectrophotometer and  circulating  pump.   Adjust  the pump
          rate to 1 L/min.   Allow the  spectrophotometer  and pump to  stabilize.

     11.4 Cool  the BOD bottles to room temperature  and dilute  in  the following
          manner:
          11.4.1
          11.4.2
To each BOD bottle containing the CAL, LFB and LRB, add 50
mL of reagent water  (Sect. 7.1.7).

To each BOD bottle containing a tissue sample, QCS or LFM,
add 55 mL of reagent water (Sect. 7.1.7).
    11.5 To each BOD bottle, add 6 mL of sodium chloride-hydroxylamine
         sulfate solution  (Sect. 7.6) to reduce the excess permanganate.

    11.6 Treating each bottle individually:

         11.6.1
         11.6.2
Placing the aspirator inside the BOD bottle and above the
liquid, purge the head space (20 to 30 sec) to remove
possible gaseous interferents.

Add 5 mL of stannous chloride solution (Sect. 7.7) and
immediately attach the bottle to the aeration apparatus.
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          11.6.3    The absorbance,  as exhibited either on the spectro-
                    photometer or the recorder,  will  increase and reach
                    maximum within 30 sec.   As soon as the recorder pen levels
                    off, approximately 1 min,  open the bypass value (or
                    optionally remove aspirator from the BOD bottle if it is
                    vented under the hood)  and continue the aeration until  the
                    absorbance returns to its  minimum value.

     11.7 Close the bypass value, remove the aspirator from the BOD bottle and
          continue the aeration.  Repeat step  (Sect.  11.6) until all BOD
          bottles have been aerated and recorded.

12.   CALCULATIONS

     12.1 Measure the peak height of the unknown from the chart and read the
          mercury value from the standard curve.

     12.2 Calculate the mercury concentration  in the sample by the formula:
                    Hal a =  _ W Hg in the
                     *  *    wt.  of  the aliquot in  grams


     12.3 Report mercury concentrations as follows:  Below 0.1 jug/g, <
          0.1 M9/g; between 0.1 and 1 M9/9> to the nearest 0.01 /ug; between 1
          and 10 p,g/g, to nearest 0.1 jug; above 10 jug/g,  to  nearest /ug.

13.  PRECISION AND ACCURACY

     13.1 The standard deviation for mercury in fish tissue samples are
          reported as 0.19 ± 0.02 #g Hg/g , 0.74 ± 0.05 fig Hg/g and 0.74 ±
          0.05 tig Hg/g with recoveries for LFM being 112%, 93%, and 86%,
          respectively.  These tissue samples were fortified with methyl
          mercuric chloride.

14.  REFERENCES

     1.   "Safety in Academic Chemistry Laboratories", American Chemical
          Society Publication, Committee on Chemical Safety, 3rd Edition,
          1979.

     2.   "OSHA Safety and Health Standards, General Industry", (29CFR 1910),
          Occupational Safety and Health Administration, OSHA 2206, revised
          January, 1976.

     3.   "Proposed OSHA Safety and Health Standards, Laboratories",
          Occupational Safety and Health Administration, Federal Register,
          July 24, 1986.

     4.   "Specification for Reagent Water," Annual Book of ASTM Standards,
          D1193, Vol. 11.01, 1990.


                                      291

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5.   National Institute of Standards and Technology, Office of Standards
     Reference Materials, Gaithersburg, MD 20899:  Aquatic Plant -
     Lagarosiphon major (CRN 8030), Aquatic Plant - Platihypnidium
     riparioides (CRM 8031), Oyster Tissue (SRM 1566a), Albacore Tuna
     (RM 50).

6.   National Research Council of Canada, Marine Analytical Chemistry
     Standards Program, Division of Chemistry, Montreal Road, Ottawa,
     Ontario K1A OR9, Canada:  Dogfish Liver  (DOLT-1), Dogfish Muscle
     (DORM-1), Non Defatted Lobster Hepatopancreas (LUTS-1), Lobster
     Hepatopancreas (TORT-1).

7.   Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.
                                292

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            O* BUBBLER
ABSORPTION
    CELL
     SAMPLE  SOLUTION
     IN BOO  BOTTLE
SCRUBBER
CONTAINING
A MERCUR*
ABSORBMG
MEDIA
         Figurt 1.  Apparatus for Flaaeltss Mercury Determination
Because of the  toxic nature of mercury vapor, inhalation must be avoided.
Therefore, a  bypass has been Included 1n the system to either vent the mercury
vapor Into a  exhaust hood or pass  the vapor through some absorbing media, such
as:    a)  equal  volumes of O.i N KMn04 and 10% H2SO,
       b)  0.25% Iodine in a 3% KI  solution.
A specially treated charcoal that  will absorb mercury vapor  is also available
from Barnebey and Cheney, P.O. Box 2526, Columbus,  OH  43216, Catalog No. 580-
13 or 580-22.
                                    293
                                                         •U.S. Government Printing Office: 1991— 54S-187/40551

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