EPA-821-R-01-010
                                      January 2001
                  METHOD 200.7

TRACE ELEMENTS IN WATER, SOLIDS, AND BIOSOLIDS
BY INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION
                 SPECTROMETRY
                   Revision 5.0

                   January 2001
        U.S. Environmental Protection Agency
          Office of Science and Technology
                Ariel Rios Building
           1200 Pennsylvania Avenue, N.W.
              Washington, D.C. 20460

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Method 200.7
                                Acknowledgments
Revision 5.0 of Method 200.7 was prepared under the direction of William A. Telliard of the U.S.
Environmental Protection Agency's (EPA's) Office of Water (OW), Engineering and Analysis Division
(EAD) in collaboration with Ted Martin, of EPA's Office of Research and Development's National
Exposure Research Laboratory in Cincinnati, Ohio.  The method was prepared under EPA Contract 68-
C3-0337 and 68-C-98-139 by DynCorp I&ET with assistance from Quality Works, Inc. and Westover
Scientific, Inc.

The following personnel at the EPA Office of Research and Development's National Exposure Research
Laboratory in Cincinnati, Ohio, are gratefully acknowledged for the development of the analytical
procedures described in this method:

USEPA-ICP Users Group (Edited by T.D. Martin and J.F. Kopp) - Method 200.7, Revision 1.0, (Printed
1979, Published 1982)

T.D. Martin  and E.R. Martin - Method 200.7, Revision 3.0 (1990)

T.D. Martin, C.A. Brockhoff, J.T. Creed, and S.E. Long (Technology Applications Inc.) - Method 200.7,
Revision 3.3 (1991)

T.D. Martin, C.A. Brockhoff, J.T. Creed, and EMMC Methods Work Group - Method 200.7, Revision 4.4
(1994)


                                      Disclaimer

This draft method has been reviewed and approved for publication by the Analytical Methods Staff within
the Engineering and Analysis Division of the U.S. Environmental Protection Agency.  Mention of trade
names or commercial products does not constitute endorsement or recommendation for use.  EPA plans
further validation of this draft method. The method may be revised following validation to reflect results of
the study. This method version contains minor editorial changes to the October 2000 version.

EPA welcomes suggestions for improvement of this method.  Suggestions and questions concerning this
method or its application should be addressed to:

W.A. Telliard
Analytical Methods Staff (4303)
Office of Science and Technology
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, N.W.
Washington, D.C. 20460
Phone: 202/260-7134
Fax:  202/260-7185
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                                                                                      Method 200.7
    Note: This method is performance based. The laboratory is permitted to omit any step or modify any
    procedure provided that all performance requirements in this method are met. The laboratory may not
    omit any quality control analyses.  The terms "shall," "must," and "may not" define procedures required
    for producing reliable results.  The terms "should" and "may" indicate optional  steps that may be
    modified or omitted if the laboratory  can demonstrate that  the modified  method produces results
    equivalent or superior to results produced by this method.
January 2001                                    Draft

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                           Method 200.7


      Trace Elements in Water, Solids, and Biosolids by
 Inductively Coupled Plasma-Atomic Emission Spectrometry


1.0  Scope and Application

1.1   Inductively coupled plasma-atomic emission spectrometry (ICP-AES) is used to
     determine metals and some nonmetals in solution. This method is a
     consolidation of existing methods for water, wastewater, and solid wastes
     (References 1-4). For analysis of petroleum products see References 5 and 6.
     This method is applicable to the following analytes:
           Analyte
         Chemical Abstract Services
         Registry Number (CASRN)
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Cerium3
Chromium
Cobalt
Copper
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Phosphorus
Potassium
Selenium
Silicab
Silver
(Al)
(Sb)
(As)
(Ba)
(Be)
(B)
(Cd)
(Ca)
(Ce)
(Cr)
(Co)
(Cu)
(Fe)
(Pb)
(Li)
(Mg)
(Mn)
(Hg)
(Mo)
(Ni)
(P)
(K)
(Se)
(Si02)
(Ag)
7429-90-5
7440-36-0
7440-38-2
7440-39-3
7440-41-7
7440-42-8
7440-43-9
7440-70-2
7440-45-1
7440-47-3
7440-48-4
7440-50-8
7439-89-6
7439-92-1
7439-93-2
7439-95-4
7439-96-5
7439-97-6
7439-98-7
7440-02-0
7723-14-0
7440-09-7
7782-49-2
7631-86-9
7440-22-4

January 2001
Draft

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Method 200.7
                                                Chemical Abstract Services
            Analyte                             Registry Number (CASRN)
Sodium
Strontium
Thallium
Tin
Titanium
Vanadium
Yttrium
Zinc
(Na)
(Sr)
(Tl)
(Sn)
(Ti)
(V)
(Y)
(Zn)
7440-23-5
7440-24-6
7440-28-0
7440-31-5
7440-32-6
7440-62-2
7440-65-5
7440-66-6
            aCerium has been included as a method analyte for correction of potential
            inter-element spectral interference.
            bThis method is not suitable for the determination of silica in solids.

1.2   To confirm approval of this method for use in compliance monitoring programs
      [e.g., Clean Water Act (NPDES) or Safe Drinking Water Act (SDWA)] consult
      both the appropriate sections of the Code of Federal Regulation (40 CFR Part
      136 Table 1B for NPDES, and Part 141  141.23 for drinking water)  and the
      latest Federal Register announcements.

1.3   ICP-AES can be used to determine dissolved analytes in aqueous samples after
      suitable filtration and acid preservation.  To reduce potential interferences,
      dissolved solids should be <0.2% (w/v) (Section 4.2).

1.4   With the exception of silver, where this method is approved for the determination
      of certain metal and metalloid contaminants in drinking water, aqueous samples
      may be analyzed directly by pneumatic nebulization without acid digestion if the
      sample has been properly preserved with acid and has turbidity of <1 NTU at the
      time of analysis. This total recoverable determination procedure is referred to as
      "direct analysis." However, in the determination of some primary drinking water
      metal contaminants, preconcentration of the sample may be required prior to
      analysis in order to meet drinking water acceptance performance criteria
      (Sections 11.2.2 through 11.2.7).

1.5   For the determination of total recoverable analytes in aqueous,  biosolids
      (municipal sewage sludge), and solid samples, a digestion/extraction is required
      prior to analysis when the elements are not in solution (e.g., soil, sludge,
      sediment,  and aqueous samples that may contain particulate and suspended
      solids).  Aqueous samples containing total suspended solids>1% (w/v) should
      be extracted as a solid type sample.
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                                                                        Method 200.7
1.6   When determining boron and silica in aqueous samples, only plastic, PTFE or
      quartz labware should be used from time of sample collection to completion of
      analysis.  For accurate determination of boron in solid and sludge samples, only
      quartz or PTFE beakers should be used during acid extraction with immediate
      transfer of an extract aliquot to a plastic centrifuge tube following dilution of the
      extract to volume. When possible, borosilicate glass should be avoided to
      prevent contamination of these analytes.

1.7   Silver is only slightly soluble in the presence of chloride unless there is a
      sufficient chloride concentration to form the soluble chloride complex.
      Therefore, low  recoveries of silver may occur in samples, fortified sample
      matrices and even fortified blanks if determined as a dissolved analyte or by
      "direct analysis" where the sample has not been processed using the total
      recoverable mixed acid digestion.  For this reason it is recommended that
      samples be digested prior to the determination of silver.  The total recoverable
      sample digestion procedure given  in 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 aliquots should be prepared until the
      analysis solution contains <0.1 mg/L silver. The extraction of solid or sludge
      samples containing concentrations of silver >50 mg/kg should be treated in a
      similar manner.

      NOTE:  When analyzing samples containing high levels of silver as might occur in the
      photographic manufacturing industries, EPA Method 272.1 can be used for silver
      determinations. Based on the use of cyanogen iodide (CNI) as a stabilizing agent, Method 272.1
      can be used on samples containing up to 4 mg/L ofAg. However, it should be recognized that
      CNI is an extremely hazardous and environmentally toxic reagent, and should be used with the
	utmost caution.	

1.8   The extraction  of tin  from solid or sludge samples should be prepared using
      aliquots <1 g when determined sample concentrations exceed 1%.

1.9   The total recoverable sample digestion procedures given in this method will
      solubilize and hold in solution  only minimal concentrations of barium in the
      presence of free sulfate.  For the analysis of barium in samples having varying
      and unknown concentrations of sulfate,  analysis should be completed as soon
      as possible  after sample preparation.

1.10  The total recoverable sample digestion procedure given in this method is not
      suitable for the determination of volatile organo-mercury compounds.  However,
      if digestion is not required (turbidity <1 NTU), the combined concentrations of
      inorganic and organo-mercury in solution can be determined by "direct analysis"
      pneumatic nebulization provided the sample solution is adjusted to contain the
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Method 200.7
      same mixed acid (HN03 + HCI) matrix as the total recoverable calibration
      standards and blank solutions.

1.11  This method will be validated in biosolids for those analytes regulated under 40 CFR Part
      503 only. It is believed to be applicable for the analysis of biosolids for all analytes listed
      in Section 1.1. There may be difficulties in analyzing molybdenum in biosolids with a
      radial TCP, thus the determination of some analytes in biosolids may require the use of an
      axial TCP. More information will be provided by the validation study.
1.12  Detection limits and linear ranges for the elements will vary with the wavelength
      selected, the spectrometer, and the matrices.  Method detection limits (MDLs; 40
      CFR 136, appendix B) and minimum levels (MLs) when no interferences are
      present will be determined for this method through a validation study.
      Preliminary MDL values are given in Table 4.  The ML for each analyte can be
      calculated by multiplying the MDL by 3.18 and rounding to the nearest (2, 5, or
      10X10") where n is an  integer.

1.13  Users of the method data should state the data-quality objectives prior to
      analysis.  Users of the method must document and have  on file the required
      initial demonstration performance data described in Section 9.2 prior to using
      the method for analysis.

2.0   Summary of Method

2.1   An aliquot of a well-mixed, homogeneous sample is accurately weighed or
      measured for sample  processing. For total recoverable analysis of a solid or an
      aqueous sample containing undissolved material, analytes are solubilized by
      gentle refluxing with HN03 and HCI.  For the total recoverable analysis  of a
      sludge sample containing  <1% total  suspended solids, analytes are solubilized
      by successive refluxing with HN03 and HCI. For total recoverable analysis of a
      sludge sample containing  total suspended solids >1% (w/v), analytes are
      solubilized by refluxing with HN03, background organic materials are oxidized
      with peroxide, and analytes are further solubilized  by refluxing with HCI. After
      cooling, the sample is made up to volume, mixed and then centrifuged or
      allowed to settle overnight prior to analysis. For the  determination of dissolved
      analytes in a filtered aqueous sample aliquot,  or for the "direct analysis" total
      recoverable determination of analytes in drinking water where sample turbidity is
      <1 NTU, the sample is made ready for analysis by the addition of the appropriate
      volume  of HN03, and  then diluted to a predetermined volume and mixed before
      analysis.

2.2   The analysis described in  this method involves multi-elemental determinations
      by ICP-AES using sequential or simultaneous instruments.  The instruments
      measure characteristic atomic-line emission spectra  by optical spectrometry.
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                                                                       Method 200.7
      Samples are nebulized and the resulting aerosols are transported to the plasma
      torch.  Element specific emission spectra are produced by a radio-frequency
      inductively coupled plasma. The spectra are dispersed by a grating
      spectrometer, and the intensities of the line spectra are monitored at specific
      wavelengths by a photosensitive device. 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.  The background must be
      measured adjacent to an analyte wavelength during analysis.  Interferences
      must be considered and addressed appropriately as discussed in Sections 4.0,
      7.0, 9.0, and 11.0.

3.0   Definitions

3.1   Biosolids-A solid, semisolid, or liquid residue (sludge) generated during
      treatment of domestic sewage in a treatment works.

3.2   Calibration blank-A volume of reagent water acidified with the same acid matrix
      as the calibration standards (Section 7.12.1). The calibration blank is a zero
      standard and is used to calibrate the ICP instrument.

3.3   Calibration standard-A solution prepared from the dilution of stock standard
      solutions (Section 7.11). The calibration solutions are used to calibrate the
      instrument response with respect to analyte concentration.

3.4   Calibration verification (CV) solution-A solution of method analytes, used to
      evaluate the performance of the instrument system with respect to a defined set
      of method criteria (Section 7.13).

3.5   Dissolved analvte-The concentration of analyte in an aqueous sample that will
      pass through a 0.45 urn membrane filter assembly prior to sample acidification
      (Section 8.2).

3.6   Field blank-An aliquot of reagent water  or other blank matrix that is placed in a
      sample container in the laboratory and treated as a sample in all respects,
      including shipment to the sampling site,  exposure to the sampling site
      conditions, storage, preservation, and all analytical procedures (Section 8.5).
      The field blank is analyzed to determine if method analytes or other
      interferences are present in the field environment.

3.7   Internal standard-Pure analyte(s) added to a sample, extract, or standard
      solution in a known amount(s) and used to measure the relative responses of
      other method analytes that are components of the same sample or solution.  The
      internal standard must be an analyte that is not a sample component
      (Section  11.6).
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Method 200.7
3.8   Linear dynamic range (LDR)-The concentration range over which the instrument
      response to an analyte is linear (Section 9.2.3).

3.9   Matrix spike (MS) and matrix spike duplicate (MSD)-Two aliquots of the same
      environmental sample to which known quantities of the method analytes are
      added in the laboratory. The MS and MSD are analyzed exactly like  a sample,
      and their purpose is: to determine whether the sample matrix contributes bias to
      the analytical results, and to indicate precision associated with laboratory
      procedures. The background concentrations of the analytes in the sample
      matrix must be determined  in a separate aliquot and the measured values in the
      MS and MSD corrected for  background concentrations (Section 9.5).

3.10  Mav-This action, activity, or procedural step is neither required nor prohibited.

3.11  May  not-This action, activity, or procedural step is prohibited.

3.12  Method blank-An aliquot of reagent water or other blank matrix that is treated
      exactly as a sample including exposure to all glassware,  equipment, solvents,
      reagents, and internal standards that are used with other samples. The method
      blank is used to determine  if method analytes or other interferences are present
      in the laboratory environment,  reagents, or apparatus (Section 7.12.2).

3.13  Method detection limit (MDL)-The minimum concentration of an analyte that can
      be identified, measured, and reported with 99% confidence (Section 9.2.1).  The
      MDL is determined according to procedures described in 40 CFR Part 136,
      Appendix B.

3.14  Minimum level (ML)-The lowest level at which the entire  analytical system gives
      a recognizable signal and acceptable calibration point for the analyte. It is
      equivalent to the concentration of the lowest calibration standard, assuming that
      all method-specific sample  weights,  volumes and cleanup procedures have been
      employed.

3.15  Must-This action, activity, or procedural step is required.

3.16  Ongoing precision and recovery standard (OPR)-The  OPR test is used to
      ensure that the laboratory meets performance criteria during the period that
      samples are analyzed. It also  separates laboratory performance from method
      performance on the sample matrix.  For aqueous samples, the OPR solution is
      an aliquot of method blank  to which  known quantities of the method analytes are
      added in the laboratory. For solid samples, the use of clean sand, soil or peat
      moss to which known quantities of the method analytes are added in  the
      laboratory is recommended. The OPR is analyzed in the same manner as
      samples (Section 9.7).


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                                                                       Method 200.7
3.17  Plasma solution-A solution that is used to determine the optimum height above
      the work coil for viewing the plasma (Section 7.16).

3.18  Reference sample-A solution of method analytes of known concentrations which
      is used to fortify an aliquot of method blank or sample matrix (Section 7.14). The
      reference sample is obtained from a source external to the laboratory and
      different from the source of calibration standards. It is used to check laboratory
      and/or instrument performance.

3.19  Shall-This action, activity or procedural step is required.

3.20  Should-This action, activity, or procedural step is suggested but not required.

3.21  Solid sample-For the purpose of this method, a sample taken from material
      classified as either soil, sediment or industrial sludge.

3.22  Spectral interference check (SIC) solution-A solution of selected method
      analytes of higher concentrations which is used to evaluate the procedural
      routine for correcting known inter-element spectral interferences with respect to
      a defined set of method  criteria  (Sections 7.15 and 9.4).

3.23  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 either an operative
      matrix  effect or the sample analyte concentration (Sections 9.5.3.1 and 11.6).

3.24  Standard stock solution-A concentrated solution containing one or more method
      analytes prepared in the laboratory using assayed reference materials or
      purchased from a reputable commercial source (Section 7.10).

3.25  Total recoverable analvte-The concentration of analyte determined either by
      "direct analysis" of an unfiltered acid preserved drinking water sample  with
      turbidity of <1 NTU (Section 11.2.1), or by analysis of the solution extract of a
      sludge, solid, or unfiltered aqueous sample following digestion by refluxing with
      hot dilute mineral acid(s) as specified in the method (Sections 11.2 through
      11.4).

3.26  Total Solids-The residue left in  the vessel after evaporation of liquid from a
      sample and  subsequent drying in an oven at 103C to 105C.

3.27  Water  sample-For the purpose  of this method, a sample taken from  one of the
      following sources: drinking, surface, ground, storm runoff, industrial or domestic
      wastewater.
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Method 200.7
4.0   Interferences

4.1   Spectral interferences are caused by background emission from continuous or
      recombination phenomena, stray light from the line emission of high
      concentration elements, overlap of a spectral line from another element, or
      unresolved overlap of molecular band spectra.

      4.1.1  Background emission and stray light can usually be compensated for by
            subtracting the background emission determined by measurement(s)
            adjacent to the analyte wavelength peak.  Spectral scans of samples or
            single element solutions in the analyte regions may indicate not only
            when alternate wavelengths are desirable because of severe spectral
            interference, but also will show whether the most appropriate estimate of
            the background emission is provided by an interpolation from
            measurements on both sides of the wavelength peak or by the measured
            emission on one side or the other. The location(s) selected for the
            measurement of background intensity will be determined by the
            complexity of the spectrum adjacent to the wavelength peak. The
            location(s) used for routine measurement must be free of off-line spectral
            interference (inter-element or molecular)  or adequately corrected to
            reflect the same change in background intensity as occurs at the
            wavelength peak.

      4.1.2  Spectral overlaps may be avoided by using an alternate wavelength or
            can be compensated for by equations that correct for inter-element
            contributions, which involves measuring the interfering elements.  Some
            potential on-line spectral interferences observed for the recommended
            wavelengths are given in Table 2. When operative and uncorrected,
            these interferences will produce false positive determinations and be
            reported as analyte concentrations. The interferences listed are only
            those that occur between method analytes.  Only interferences of a direct
            overlap nature that were observed with a single instrument having a
            working resolution of 0.035 nm are listed.  More extensive information on
            interferant effects at various wavelengths and resolutions is available in
            Boumans' Tables (Reference 8).  Users may apply inter-element
            correction factors determined on their instruments within tested
            concentration  ranges to compensate (off-line or on-line) for the effects of
            interfering elements.

      4.1.3  When inter-element corrections are applied, there is a need to verify their
            accuracy by analyzing spectral interference check solutions as described
            in Section 7.15.  Inter-element corrections will vary for the same emission
            line among instruments because of differences in resolution, as
            determined by the grating plus the entrance and exit slit widths, and by
            the order of dispersion.  Inter-element corrections will also vary

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                                                                      Method 200.7
            depending upon the choice of background correction points.  Selecting a
            background correction point where an interfering emission line may
            appear should be avoided when practical. Inter-element corrections that
            constitute a major portion of an emission signal may not yield accurate
            data. Users should not forget that some samples may contain uncommon
            elements that could contribute spectral interferences (References 7 and
            8).

      4.1.4 The interference effects must be evaluated for each individual instrument
            whether configured as a sequential or simultaneous instrument.  For each
            instrument, intensities will vary not only with optical resolution but also
            with operating conditions  (such as power, viewing height and argon flow
            rate). When using the recommended wavelengths given in Table 1, the
            analyst is  required to determine and document for each wavelength the
            effect from the known interferences given in  Table 2, and to use a
            computer  routine for their automatic correction on all analyses.  To
            determine the appropriate location for off-line background correction, the
            user must scan the area on either side adjacent to the wavelength  and
            record the apparent emission intensity from all other method analytes.
            This spectral information must be documented and kept on file.   The
            location selected for background correction must either be free  of off-line
            inter-element spectral interference or a computer routine must be used for
            automatic correction on all determinations.  If a wavelength other than the
            recommended wavelength is used, the user  must determine and
            document both the on-line and off-line spectral interference effect from all
            method analytes and provide for automatic correction on all  analyses.
            Tests to determine the spectral interference  must be done using analyte
            concentrations that will  adequately describe the interference. Normally,
            100 mg/L  single element solutions are sufficient,  however, for analytes
            such as iron that may be found at  high concentration a more appropriate
            test would be to use a concentration  near the upper LDR limit.  See
            Section 9.4 for required spectral interference test criteria.

      4.1.5 When inter-element corrections are not used, either ongoing SIC
            solutions (Section 7.15) must be analyzed to verify the absence of inter-
            element spectral interference, or a computer software routine must be
            employed for comparing the determinative data to limits files for notifying
            the analyst when an interfering element is detected in the sample at a
            concentration that will produce either an apparent false positive
            concentration greater than the analyte MDL, or false negative analyte
            concentration less than the 99% lower control limit of the calibration
            blank.  When the interference accounts for 10% or more of the analyte
            concentration, either  an alternate wavelength free of interference or
            another approved test procedure must be used to complete the analysis.
            For example, the copper peak at 213.853 nm could be mistaken for the

January 2001                              Draft                                      ~9

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Method 200.7
            zinc peak at 213.856 nm in solutions with high copper and low zinc
            concentrations. For this example, a spectral scan in the 213.8 nm region
            would not reveal the misidentification because a single peak near the zinc
            location would be observed.  The possibility of misidentification of copper
            for the zinc peak at 213.856 nm can be identified by measuring the
            copper at another emission line, e.g., 324.754 nm.  Users should be
            aware that, depending upon the instrumental  resolution, alternate
            wavelengths with adequate sensitivity and freedom from interference may
            not be available for all matrices. In these circumstances the analyte must
            be determined using another approved test procedure.

4.2   Physical interferences are effects associated  with the sample nebulization and
      transport processes.  Changes in viscosity and surface tension can cause
      significant inaccuracies, especially in samples containing  high dissolved solids
      or high acid concentrations. If physical interferences are present, they must be
      reduced by such means as a high-solids nebulizer, diluting the sample, using a
      peristaltic pump, or using an appropriate internal standard element. Another
      problem that can occur with high dissolved solids is  salt buildup at the tip of the
      nebulizer, which affects aerosol flow rate and causes instrumental drift.  This
      problem can be controlled by a high-solids nebulizer, wetting the argon prior to
      nebulization, using a tip washer, or diluting the sample. Also, it has been
      reported that better control of the argon flow rates, especially for the nebulizer,
      improves instrument stability and precision; this is accomplished with the use  of
      mass flow controllers.

4.3   Chemical interferences include molecular-compound formation, ionization
      effects,  and solute-vaporization effects. Normally, these effects are not
      significant with the ICP-AES technique. If observed, they  can be minimized by
      careful selection of operating conditions (such as incident power and
      observation height), by buffering of the sample,  by matrix matching, and by
      standard-addition procedures.  Chemical interferences are highly dependent on
      matrix type and the specific analyte element.

4.4   Memory interferences result when analytes in a previous sample contribute to
      the signals measured in a new sample.  Memory effects can result from sample
      deposition on the uptake tubing to the nebulizer, 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 (Section  7.12.1). 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 must be estimated prior to analysis.  This may be achieved by
      aspirating a standard containing elements corresponding to either their LDR or a
      concentration ten times those usually encountered.  The aspiration time should
      be the same as a normal  sample analysis period, followed by analysis of the

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                                                                       Method 200.7
      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 requires a rinse
      period  of at least 60 seconds between samples and standards.  If a memory
      interference is suspected, the sample must be analyzed again after a long rinse
      period.

5.0   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 awareness
      file of OSHA regulations regarding the safe handling of the chemicals specified
      in this  method (References 9, 10,  11, and 12). A reference file of material data
      handling sheets should also be made available to all personnel involved in the
      chemical analysis. Specifically, concentrated HN03and HCI present various
      hazards and are moderately toxic and  extremely irritating to skin and mucus
      membranes.  Use these reagents in a fume 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, protective clothing, and observe proper
      mixing when working with these reagents.

5.2   The acidification of samples containing reactive materials may result in the
      release of toxic gases, such as cyanides or sulfides. Acidification and digestion
      of samples should be done in a fume hood.

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   The inductively coupled plasma should only be viewed with proper eye
      protection from the ultraviolet emissions.

5.5   It is the responsibility of the user of this method to comply with relevant disposal
      and waste regulations.  For guidance,  see Sections 14.0  and 15.0.

6.0   Equipment and Supplies

      NOTE: The mention of trade names or commercial products in this method is for illustrative
      purposes only and does not constitute endorsement or recommendation for use by the EPA.
      Equivalent performance may be achievable using apparatus and materials other than those
	suggested here.  The laboratory is responsible for demonstrating equivalent performance.	
January 2001                             Draft                                     11

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Method 200.7
6.1   Inductively coupled plasma emission spectrometer:

      6.1.1  Computer-controlled emission spectrometer with background-correction
            capability.  The spectrometer must be capable of meeting and complying
            with the requirements described and referenced in Section 2.2.

      6.1.2  Radio-frequency generator compliant with FCC regulations.

      6.1.3  Argon gas supply-High purity grade (99.99%).  When analyses are
            conducted frequently, liquid argon is more economical and requires less
            frequent replacement  of tanks than compressed argon in conventional
            cylinders.

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

      6.1.5  (Optional)  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.

6.2   Analytical balance, with capability to measure to 0.1  mg, for use in weighing
      solids, for preparing standards, and for determining dissolved solids in digests or
      extracts.

6.3   A temperature adjustable hot plate capable of maintaining a temperature of
      95C.

6.4   (Optional)  A temperature adjustable block digester capable of maintaining a
      temperature of 95C and equipped  with 250-mL constricted digestion tubes.

6.5   (Optional)  A steel cabinet centrifuge with guard bowl, electric timer and brake.

6.6   A gravity convection drying oven with thermostatic control capable of
      maintaining 180C5C.

6.7   (Optional)  An air displacement pipetter capable of delivering volumes ranging
      from 0.1-2500 uL with an assortment of high quality disposable pipet tips.

6.8   Mortar and pestle, ceramic or other nonmetallic material.

6.9   Polypropylene sieve, 5-mesh (4  mm opening).

6.10  Labware-Prevention of contamination and loss are of prime consideration for
      determination of trace levels of elements. Potential contamination sources

12                                      Draft                               January 2001

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                                                                      Method 200.7
      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, and
      (2) depleting element concentrations through adsorption processes.  All
      reusable labware (glass, quartz, polyethylene, PTFE, FEP, etc.) should be
      sufficiently clean for the task objectives.  One recommended procedure found to
      provide clean labware includes washing with a detergent solution, rinsing with
      tap water, soaking for four hours or more in 20% (v/v) HN03 or a mixture of
      HN03 and HCI (1 +2+9), rinsing with reagent water and storing clean
      (References 2 and 3). Chromic acid cleaning solutions must be avoided
      because chromium is an analyte.

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

      6.10.2  Assorted calibrated pipettes.

      6.10.3  Conical Phillips beakers (Corning 1080-250 or equivalent), 250-mL with
             50-mm watch glasses.

      6.10.4  Griffin beakers, 250-mL with 75-mm watch glasses and (optional) 75-mm
             ribbed watch glasses.

      6.10.5  (Optional) PTFE and/or quartz Griffin beakers, 250-mL with PTFE covers.

      6.10.6  Narrow-mouth storage bottles, FEP (fluorinated ethylene propylene) with
             screw closure, 125-mL to 1-L capacities.

      6.10.7  One-piece stem FEP wash bottle  with screw closure, 125-mL capacity.

7.0   Reagents and  Standards

7.1   Reagents may contain elemental impurities which might affect analytical data.
      Only high purity reagents that conform to the American  Chemical Society
      specifications should be  used whenever possible (Reference 13). If the purity of
      a reagent is in question,  analyze for contamination.  All acids used for this
      method must be of ultra-high purity grade or equivalent. Suitable acids are
      available from  a number of manufacturers.  Redistilled acids prepared by sub-
      boiling distillation are acceptable.

7.2   Hydrochloric acid, concentrated (specific gravity = 1.19).
January 2001                              Draft                                     13

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Method 200.7
      7.2.1  Hydrochloric acid (1+1 )-Add 500 ml concentrated HCI to 400 ml reagent
            water and dilute to 1 L.

      7.2.2  Hydrochloric acid (1+4)-Add 200 ml concentrated HCI to 400 ml reagent
            water and dilute to 1 L.

      7.2.3  Hydrochloric acid (1+20)-Add 10 ml concentrated HCI to 200 ml reagent
            water.

7.3   Nitric acid, concentrated (specific gravity = 1.41).

      7.3.1  Nitric acid (1 +1 )-Add 500 ml concentrated HN03 to 400 ml reagent
            water and dilute to 1 L.

      7.3.2  Nitric acid (1 +2)-Add 100 ml concentrated HN03 to 200 ml reagent
            water.

      7.3.3  Nitric acid (1 +5)-Add 50 ml concentrated HN03 to 250 ml reagent water.

      7.3.4  Nitric acid (1 +9)-Add 10 ml concentrated HN03 to 90 ml reagent water.

7.4   Reagent water-All references to water in this method refer to ASTM Type  I
      grade water (Reference 14).

7.5   Ammonium hydroxide, concentrated (specific gravity = 0.902).

7.6   Tartaric acid-ACS reagent grade.

7.7   Hydrogen peroxide-H202.

      7.7.1  Hydrogen peroxide,  50%, stabilized certified reagent grade.

      7.7.2  Hydrogen peroxide,  30%, stabilized certified reagent grade.

7.8   Clean sand or soil-All references to clean sand or soil in this method refer to
      sand or soil certified to be free of the analytes of interest at or above their  MDLs
      or to contain those analytes at certified  levels.

7.9   Peat moss-All references to peat moss  in this method refer to sphagnum peat
      moss free of arsenic, cadmium, copper, lead, mercury, molybdenum, nickel,
      selenium and zinc analytes at or above their MDLs (Table 4) or to contain  those
      analytes at certified  levels.
14                                     Draft                              January 2001

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                                                                      Method 200.7
7.10  Standard Stock Solutions-Stock standards may be purchased or prepared from
      ultra-high purity grade chemicals (99.99-99.999% pure). All compounds must be
      dried for one hour at 105C, unless otherwise specified. It is recommended that
      stock solutions be stored in FEP bottles. Replace stock standards when
      succeeding dilutions for preparation of calibration standards cannot be verified.
CAUTION:   Many of these chemicals are extremely toxic if inhaled or swallowed
            (Section 5.1). Wash hands thoroughly after handling.
      Typical stock solution preparation procedures follow for 1 L quantities
      (Equations 1 and 2), but for the purpose of pollution prevention, the analyst is
      encouraged to prepare smaller quantities when possible.  Concentrations are
      calculated based upon the weight of the pure element or upon the weight of the
      compound multiplied by the fraction of the analyte in the compound.

                                  Equation 1
            From pure element,
                                        m
                                    c = 
                                        V
            where:
                  C = concentration (mg/L)
                  m = mass (mg)
     	V = volume (L)	
                                  Equation 2
            From pure compound,
                                     (
                                  C =
                                        V
            where:
                  C = concentration (mg/L)
                  m = mass (mg)
                  V = volume (L)
                  gf= gravimetric factor (the weight fraction of the analyte in the
compound)
      7.10.1 Aluminum solution, stock, 1 ml = 1000 ug AI-Dissolve 1.000 g of
            aluminum metal, weighed accurately to at least four significant figures, in
            an acid mixture of 4.0 ml of (1 +1) HCI and 1 ml of concentrated HN03 in
            a beaker.  Warm beaker slowly to effect solution. When dissolution is

January 2001                             Draft                                    ~

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Method 200.7
            complete, transfer solution quantitatively to a 1-L flask, add an additional
            10.0 ml of (1 +1) HCI and dilute to volume with reagent water.

      7.10.2 Antimony solution, stock, 1 ml = 1000 ug Sb-Dissolve 1.000 g of
            antimony powder, weighed accurately to at least four significant figures, in
            20.0 ml (1+1) HN03 and 10.0 ml concentrated HCI. Add 100 ml reagent
            water and 1.50 g tartaric acid. Warm solution slightly to effect complete
            dissolution.  Cool solution and add reagent water to volume in a 1-L
            volumetric flask.

      7.10.3 Arsenic solution, stock, 1 ml = 1000 ug As-Dissolve 1.320 g of As203 (As
            fraction = 0.7574), weighed accurately to at least four significant figures,
            in 100 ml of reagent water containing 10.0 ml concentrated NH4OH.
            Warm the solution gently to effect dissolution. Acidify the solution with
            20.0 ml concentrated HN03 and dilute to volume in a 1-L volumetric flask
            with reagent water.

      7.10.4 Barium solution, stock, 1 ml = 1000 ug Ba-Dissolve 1.437 g BaC03 (Ba
            fraction = 0.6960), weighed accurately to at least four significant figures,
            in 150 ml (1+2) HN03 with heating and stirring to de-gas and dissolve
            compound.  Let solution cool and dilute with reagent water in 1-L
            volumetric flask.

      7.10.5 Beryllium solution, stock, 1 mL = 1000 ug Be-DO NOT DRY.  Dissolve
            19.66 g BeSCy4H20 (Be fraction = 0.0509), weighed accurately to at
            least four significant figures, in reagent water, add  10.0 mL concentrated
            HN03, and dilute to volume in a 1 -L volumetric flask with reagent water.

      7.10.6 Boron solution, stock, 1 mL = 1000 ug B-DO NOT DRY. Dissolve 5.716 g
            anhydrous H3B03 (B fraction = 0.1749), weighed accurately to at least
            four significant figures, in reagent water and dilute in a 1-L volumetric
            flask with reagent water. Transfer immediately after mixing to a clean
            FEP bottle to minimize any leaching of boron from  the glass volumetric
            container. Use of a non-glass volumetric flask is recommended to avoid
            boron contamination from glassware.

      7.10.7 Cadmium solution, stock, 1 mL = 1000 ug Cd-Dissolve 1.000 g Cd metal,
            acid cleaned with (1+9) HN03, weighed accurately to at least four
            significant figures, in 50 mL (1 +1) HN03 with heating to effect dissolution.
            Let solution cool and dilute with reagent water in a 1 -L volumetric flask.

      7.10.8 Calcium solution, stock, 1 mL = 1000 ug Ca-Suspend 2.498 g CaC03
            (Ca fraction = 0.4005), dried at 180C for one hour before weighing,
            weighed  accurately to at least four significant figures, in reagent water
            and dissolve cautiously with a minimum amount of (1 +1) HN03. Add

16                                     Draft                               January 2001

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                                                                      Method 200.7
            10.0 ml concentrated HN03 and dilute to volume in a 1-L volumetric flask
            with reagent water.

      7.10.9 Cerium solution, stock, 1 ml = 1000 ug Ce-Make a slurry of 1.228 g
            Ce02 (Ce fraction = 0.8141), weighed accurately to at least four
            significant figures, in 100 ml concentrated HN03 and evaporate to
            dryness.  Make another slurry of the residue in 20 ml H20,  add 50 ml
            concentrated HN03, with heat and stirring add 60 ml 50% H202 drop-wise
            in 1 ml increments allowing periods of stirring between the  1 ml
            additions. Boil off excess H202 before diluting to volume in  a 1-L
            volumetric flask with reagent water.

      7.10.10     Chromium solution, stock, 1 ml = 1000 ug Cr-Dissolve 1.923 g
                  Cr03 (Cr fraction = 0.5200), weighed accurately to at least four
                  significant figures, in 120 ml (1+5) HN03.  When solution is
                  complete,  dilute to volume in a 1-L volumetric flask with reagent
                  water.

      7.10.11      Cobalt solution, stock, 1  ml = 1000 ug Co-Dissolve  1.000 g Co
                  metal,  acid cleaned with  (1+9) HN03, weighed accurately to at
                  least four significant figures, in 50.0 ml (1 +1) HN03.  Let solution
                  cool and dilute to volume in a 1 -L volumetric flask with reagent
                  water.

      7.10.12     Copper solution, stock, 1 ml = 1000 ug Cu-Dissolve 1.000 g Cu
                  metal,  acid cleaned with  (1+9) HN03, weighed accurately to at
                  least four significant figures, in 50.0 ml (1 +1) HN03 with heating to
                  effect dissolution.  Let solution cool and dilute in a 1-L volumetric
                  flask with reagent water.

      7.10.13     Iron solution, stock, 1 mL = 1000 ug Fe-Dissolve 1.000 g Fe metal,
                  acid cleaned with (1+1) HCI, weighed accurately to four significant
                  figures, in  100 mL (1+1)  HCI with  heating to effect dissolution.  Let
                  solution cool and dilute with reagent water in a 1-L volumetric flask.

      7.10.14     Lead solution, stock, 1 mL = 1000 ug Pb-Dissolve 1.599 g
                  Pb(N03)2 (Pb fraction = 0.6256), weighed accurately to at least four
                  significant figures, in a minimum amount of (1 +1) HN03.  Add 20.0
                  mL (1 +1) HN03 and dilute to volume in a 1 -L volumetric flask with
                  reagent water.

      7.10.15     Lithium solution, stock, 1 mL = 1000 ug Li-Dissolve 5.324 g Li2C03
                  (Li fraction = 0.1878), weighed accurately to at least four significant
                  figures, in  a minimum amount of (1 +1) HCI and dilute to volume in
                  a 1 -L volumetric flask with reagent water.

January 2001                             Draft                                    ~

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Method 200.7
      7.10.16     Magnesium solution, stock, 1  ml = 1000 ug Mg-Dissolve 1.000 g
                  cleanly polished Mg ribbon, accurately weighed to at least four
                  significant figures, in slowly added 5.0 ml (1+1) HCI (CAUTION:
                  reaction is vigorous).  Add 20.0 ml (1+1) HN03 and dilute to
                  volume in a 1 -L volumetric flask with reagent water.

      7.10.17     Manganese solution, stock, 1  ml = 1000 ug Mn-Dissolve 1.000 g
                  of manganese metal, weighed accurately to at least four significant
                  figures, in 50 ml (1+1) HN03  and dilute to volume in a 1-L
                  volumetric flask with reagent water.

      7.10.18     Mercury solution, stock, 1 ml = 1000 ug Hg-DO NOT DRY.
                  CAUTION: highly toxic element. Dissolve 1.354 g HgCI2 (Hg
                  fraction = 0.7388) in reagent water. Add 50.0 ml concentrated
                  HN03 and dilute to volume in  1-L volumetric flask with reagent
                  water.

      7.10.19     Molybdenum solution, stock, 1 ml = 1000 ug Mo-Dissolve 1.500 g
                  Mo03 (Mo fraction = 0.6666),  weighed accurately to at least four
                  significant figures, in a mixture of 100 ml reagent water and 10.0
                  ml concentrated NH4OH, heating to effect dissolution. Let solution
                  cool and dilute with reagent water in a 1 -L volumetric flask.

      7.10.20     Nickel solution, stock, 1 ml = 1000 ug Ni-Dissolve 1.000 g of
                  nickel metal, weighed accurately to at least four significant figures,
                  in 20.0 ml hot concentrated HN03. Cool, and  dilute to volume in a
                  1 -L volumetric flask with reagent water.

      7.10.21     Phosphorus  solution, stock, 1  ml = 1000 ug P-Dissolve 3.745 g
                  NH4H2P04 (P fraction = 0.2696), weighed accurately to at least four
                  significant figures, in 200 ml reagent water and dilute to volume in
                  a 1 -L volumetric flask with reagent water.

      7.10.22     Potassium solution, stock, 1 ml = 1000 ug K-Dissolve 1.907 g KCI
                  (K fraction =  0.5244) dried at  110C, weighed accurately to at least
                  four significant figures, in reagent water, add 20 ml (1 +1) HCI and
                  dilute to volume in a 1 -L volumetric flask with reagent water.

      7.10.23     Selenium solution, stock, 1 ml = 1000 ug Se-Dissolve 1.405 g
                  Se02 (Se fraction = 0.7116), weighed accurately to at least four
                  significant figures, in 200 ml reagent water and dilute to volume in
                  a 1 -L volumetric flask with reagent water.

      7.10.24     Silica solution, stock, 1 ml = 1000 ug Si02-D0 NOT DRY.
                  Dissolve 2.964 g (NH4)2SiF6, weighed accurately to at least four
18                                     Draft                              January 2001

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                                                                      Method 200.7
                  significant figures, in 200 ml (1+20) HCI with heating at 85C to
                  effect dissolution. Let solution cool and dilute to volume in a 1-L
                  volumetric flask with reagent water.

      7.10.25     Silver solution, stock, 1 ml = 1000 ug Ag-Dissolve 1.000 g Ag
                  metal, weighed accurately to at least four significant figures, in 80
                  ml (1 +1) HN03 with heating to effect dissolution.  Let solution cool
                  and dilute with reagent water in a 1 -L volumetric flask.  Store
                  solution in amber bottle or wrap bottle completely with aluminum
                  foil to protect solution from light.

      7.10.26     Sodium solution, stock, 1 ml = 1000 ug Na-Dissolve 2.542 g NaCI
                  (Na fraction = 0.3934),  weighed accurately to at least four
                  significant figures, in reagent water.  Add 10.0 ml concentrated
                  HN03 and dilute to volume in a 1-L volumetric flask with reagent
                  water.

      7.10.27     Strontium solution, stock, 1 ml = 1000 ug Sr-Dissolve 1.685 g
                  SrC03 (Sr fraction = 0.5935), weighed accurately to at least four
                  significant figures, in 200 ml reagent water with drop-wise addition
                  of 100 ml (1 +1) HCI. Dilute to volume in a 1 -L volumetric flask
                  with reagent water.

      7.10.28     Thallium solution, stock, 1 ml = 1000 ug TI-Dissolve 1.303 g
                  TIN03 (Tl fraction = 0.7672), weighed accurately to at least four
                  significant figures, in reagent water.  Add 10.0 ml concentrated
                  HN03 and dilute to volume in a 1-L volumetric flask with reagent
                  water.

      7.10.29     Tin solution, stock, 1 ml = 1000 ug Sn-Dissolve 1.000  g Sn shot,
                  weighed accurately to at least four significant figures, in an acid
                  mixture of 10.0 ml concentrated HCI and 2.0 ml (1+1)  HN03with
                  heating to effect dissolution.  Let solution cool, add 200 ml
                  concentrated HCI, and  dilute to volume in a 1-L volumetric flask
                  with reagent water.

      7.10.30     Titanium solution, stock, 1 ml = 1000 ug Ti-DO NOT DRY.
                  Dissolve 6.138 g (NH4)2TiO(C204)2H20 (Ti fraction = 0.1629),
                  weighed accurately to at least four significant figures, in 100 ml
                  reagent water.  Dilute to volume in a 1 -L volumetric flask with
                  reagent water.

      7.10.31     Vanadium solution,  stock,  1 ml = 1000 ug V-Dissolve 1.000 g V
                  metal, acid cleaned with (1+9) HN03, weighed accurately to at
                  least four significant figures, in 50 ml (1 +1) HN03 with  heating to

January 2001                              Draft                                     ~19

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Method 200.7
                   effect dissolution. Let solution cool and dilute with reagent water to
                   volume in a 1 -L volumetric flask.

      7.10.32      Yttrium solution, stock 1 ml = 1000 ug Y-Dissolve 1.270 g Y203
                   (Y fraction = 0.7875), weighed accurately to at least four significant
                   figures, in 50 ml (1+1) HN03, heating to effect dissolution. Cool
                   and dilute to volume in a 1 -L volumetric flask with reagent water.

      7.10.33      Zinc solution, stock, 1  ml = 1000 ug Zn-Dissolve 1.000 g Zn
                   metal, acid cleaned with (1+9) HN03, weighed accurately to at
                   least four significant figures,  in 50 ml (1 +1) HN03 with heating to
                   effect dissolution. Let solution cool and dilute with reagent water to
                   volume in a 1 -L volumetric flask.

7.11  Mixed calibration standard solutions-For the analysis of  total recoverable
      digested samples, prepare mixed calibration standard solutions by combining
      appropriate volumes of the stock solutions in 500 ml volumetric flasks
      containing 20 ml (1 +1) HN03 and 20 ml (1 +1) HCI and dilute to volume with
      reagent water.  Prior to preparing the mixed standards, each stock solution
      should be analyzed separately to determine possible spectral  interferences or
      the presence of impurities. Care should be taken when preparing the mixed
      standards to ensure that the elements are compatible and stable together.  To
      minimize the opportunity for contamination by the containers, it is recommended
      that the mixed-standard solutions be transferred to acid-cleaned, never-used
      FEP fluorocarbon bottles for storage. Fresh mixed standards  should be
      prepared, as needed, with the realization that concentrations can change on
      aging. Calibration standards not prepared from primary standards must be
      initially verified using a certified reference  solution. For the recommended
      wavelengths listed in Table 1, some typical calibration standard combinations
      are given in Table 3.

      NOTE: If the addition of silver to the recommended mixed-acid calibration standard results in
      an initial precipitation, add 15 mL of reagent water and warm the flask until the solution clears.
	For this acid combination, the silver concentration should be limited to 0.5 mg/L.	


7.12  Blanks-Three types of blanks are required for the analysis. The calibration
      blank is used in establishing the analytical curve, the method blank is used to
      assess possible contamination from the sample preparation procedure,  and a
      rinse blank is used to flush the sample uptake system and nebulizer between
      standards, check solutions, and samples to reduce memory interferences.

      7.12.1 The calibration and rinse blanks are prepared by acidifying reagent water
             to the same concentrations of the acids as used for the standards.  The
             blanks should be stored separately in FEP bottles.

20                                     Draft                               January 2001

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                                                                      Method 200.7
      7.12.2 The method blank is reagent water that is carried through the same entire
            preparation scheme as the samples including sample digestion, when
            applicable. When the method blank is analyzed, it will contain all the
            reagents in the same volumes as the samples.

7.13  Calibration verification (CV) solution-The CV solution is used to verify
      instrument performance during analysis.  It should be prepared in the same acid
      mixture as the calibration standards by combining method analytes at
      appropriate concentrations.  Silver must be limited to <0.5 mg/L; while potassium
      and phosphorus, because of higher MDLs, and silica, because of potential
      contamination, should be at concentrations of 10 mg/L.  For other analytes a
      concentration of 2 mg/L is recommended. The CV solution should be prepared
      from the same standard stock solutions used to prepare the calibration
      standards and stored in an FEP bottle. Agency programs may specify or request
      that additional CV solutions be prepared  at specified concentrations in order to
      meet particular program needs.

7.14  Reference sample-Analysis of a reference sample is required for initial and
      periodic verification of calibration standards or stock standard solutions in order
      to verify instrument performance.  The reference sample must be obtained from
      an outside source different from the standard stock solutions and prepared in the
      same acid mixture as the calibration standards.  The concentration of the
      analytes in the reference sample solution should be  >1 mg/L, except silver,
      which must be limited to a concentration  of 0.5 mg/L for solution stability. The
      reference  sample solution should be stored in a FEP bottle and analyzed as
      needed to meet data-quality needs. A fresh  solution should be prepared
      quarterly or more frequently as needed. Alternatively, the reference sample may
      be a standard or certified reference material  traceable to the National Institute of
      Standards and Technology.

7.15  Spectral interference check (SIC) solutions-SIC solutions containing (a) 300
      mg/L Fe; (b) 200 mg/L Al; (c) 50 mg/L Ba; (d) 50 mg/L Be; (e) 50 mg/L Cd;  (f) 50
      mg/L Ce; (g) 50 mg/L Co; (h) 50 mg/L Cr; (i) 50 mg/L Cu; (j) 50 mg/L Mn; (k) 50
      mg/L Mo;  (I) 50 mg/L Ni; (m) 50 mg/L Sn; (n) 50 mg/L Si02; (o) 50 mg/L Ti;
      (p) 50 mg/L TI and (q) 50 mg/L V should be prepared in the same acid mixture
      as the calibration standards and stored in FEP bottles. These solutions can be
      used to periodically verify a partial list of  the  on-line  (and possible off-line) inter-
      element spectral correction factors for the recommended wavelengths given in
      Table 1. Other solutions could achieve the same objective as well.  Multi-
      element SIC solutions may be prepared and  substituted for the single element
      solutions provided an analyte is not subject to interference from more than one
      interferant in the solution (Reference 3).
January 2001                              Draft                                     21

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Method 200.7
      NOTE: If wavelengths other than those recommended in Table 1 are used, solutions other than
	those above (a through q) may be required.	


7.16  Plasma solution-The plasma solution is used for determining the optimum
      viewing height of the plasma above the work coil prior to using the method
      (Section 10.2).  The solution is prepared by adding a 5 ml aliquot from each of
      the stock standard solutions of arsenic, lead, selenium, and thallium to a mixture
      of 20 ml (1 +1) HN03 and 20 ml (1 +1) HCI and diluting to  500  ml with reagent
      water. Store in a FEP bottle.

8.0   Sample Collection, Preservation, and  Storage

8.1   Prior to the 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. The pH of all
      aqueous samples must be tested immediately prior to withdrawing an aliquot for
      processing or "direct analysis" to ensure the sample has been  properly
      preserved. If properly acid preserved, the sample can be  held  up to six months
      before analysis.

      NOTE: Do not dip pH paper or a pH meter into the sample; remove a small aliquot with a
	clean pipette and test the aliquot.	


8.2   For the determination of the dissolved elements, a sample must be filtered
      through a 0.45 urn pore diameter membrane filter at the time of collection or as
      soon thereafter as practically possible.  (Glass or plastic filtering apparatus  is
      recommended to avoid possible contamination.  Only plastic apparatus should
      be used when the determinations of boron and silica are critical).  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) HN03  to pH <2
      immediately following filtration.

8.3   For the determination of total recoverable elements in aqueous samples,
      samples are not filtered, but acidified with (1 +1) HN03 to pH <2 (normally, 3 ml
      of (1 +1) acid per liter of sample is sufficient for most ambient and drinking water
      samples).  Preservation may be done at the time of collection.  However, to
      avoid the hazards of strong acids in the field, transport restrictions, and possible
      contamination, it is recommended that samples be returned to  the laboratory
      within two weeks of collection and acid preserved upon receipt in the laboratory.
      Following acidification,  the sample should be mixed, held for 16 hours, and  then
      verified to be pH <2 just prior to withdrawing an aliquot for processing  or "direct
      analysis." If, for some reason such as high alkalinity, the sample pH is verified
      to be >2, more acid must be added,  and the sample held for 16 hours  until
      verified to be pH <2.
22                                     Draft                                January2001

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                                                                       Method 200.7
      NOTE:  When the nature of the sample is either unknown or is known to be hazardous,
	acidification should be done in a fume hood.	


8.4   Solid samples require no preservation prior to analysis other than storage at
      4C. There is no established holding time limitation for solid samples.

8.5   A field blank should be prepared and analyzed as required by the data user.
      Use the same conditions (i.e., container, filtration and preservation) as used in
      sample collection.

8.6   If a total solids determination is required, then a  separate aliquot should be
      collected following the procedure given in Section 8.0 of Appendix A.

9.0   Quality Assurance/Quality Control

9.1   Each laboratory that uses this method is required to operate a formal quality
      assurance program  (Reference 24). The minimum requirements of this program
      consist of an initial demonstration of laboratory capability,  analysis of samples
      spiked with analyte(s) of interest to evaluate and document data quality, and
      analysis of standards and blanks as tests of continued performance.  Laboratory
      performance is compared to established performance criteria to determine that
      results of the analysis meet the performance characteristics of the method.

      9.1.1 The analyst shall make an initial demonstration of the ability to generate
            acceptable accuracy and precision with this method. This ability is
            established as described in Section 9.2.

      9.1.2 In recognition of advances that are occurring in analytical technology, the
            analyst is permitted to exercise certain options to eliminate interferences
            or lower the costs of measurements. These options include alternate
            digestion, preconcentration,  cleanup procedures, and changes in
            instrumentation. Alternate determinative techniques, such as the
            substitution of a colorimetric technique or changes that degrade method
            performance, are not allowed. If an analytical technique other than the
            techniques specified in this method  is used, then that technique must
            have  a specificity equal to or better than the specificity of the techniques
            in this method for the analytes of interest.

            9.1.2.1      Each time the method is modified, the analyst is required to
                         repeat the procedure in Section 9.2.  If the change will affect
                         the detection limit of the method, the laboratory is required
                         to demonstrate that the MDL (40 CFR Part 136, Appendix B)
                         is lower than the MDL for that analyte in this method, or one-
                         third the regulatory compliance level, whichever is higher.  If

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Method 200.7
                         the change will affect calibration, the analyst must
                         recalibrate the instrument according to Section 10.0.

             9.1.2.2      The laboratory is required to maintain records of
                         modifications made to this method. These records include
                         the following, at a minimum:

                   9.1.2.2.1     The names, titles, addresses, and telephone numbers
                               of the analyst(s) who performed the analyses and
                               modification, and of the quality control officer who
                               witnessed and will verify the analyses and
                               modification.

                   9.1.2.2.2     A listing of analytes measured, by name and CAS
                               Registry number.

                   9.1.2.2.3     A narrative stating the reason(s) for the
                               modification(s).

                   9.1.2.2.4     Results from all quality control (QC) tests comparing
                               the modified method to this method, including:

                               (a)     Method detection limit
                               (b)     Calibration
                               (c)     Calibration verification
                               (d)     Initial precision and recovery
                               (e)     Ongoing precision and recovery
                               (f)     Analysis of blanks
                               (g)     Matrix spike and matrix spike duplicate
                                      analyses

                   9.1.2.2.5     Data that will allow an independent reviewer to
                               validate each determination by tracing the instrument
                               output (peak height, area, or other signal) to the final
                               result. These data are to include, where possible:

                               (a)     Sample numbers and other identifiers
                               (b)     Digestion/preparation or extraction dates
                               (c)     Analysis dates and times
                               (d)     Analysis sequence/run chronology
                               (e)     Sample weight or volume
                               (f)     Volume before the extraction/concentration
                                      step
                               (g)     Volume after each extraction/concentration
                                      step

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                                                                       Method 200.7
                               (h)    Final volume before analysis
                               (i)    Injection volume
                               (j)    Dilution data, differentiating between dilution of
                                     a sample or extract
                               (k)    Instrument and operating conditions (make,
                                     model, revision, modifications)
                               (I)    Sample introduction system (ultrasonic
                                     nebulizer, flow injection system, etc.)
                               (m)   Preconcentration system
                               (n)    Operating conditions (background corrections,
                                     temperature program, flow rates, etc.)
                               (o)    Detector  (type, operating conditions, etc.)
                               (p)    Mass spectra, printer tapes, and other
                                     recordings of raw data
                               (q)    Quantitation reports, data system outputs, and
                                     other data to link raw data to results reported

      9.1.3 Analyses of blanks are required to demonstrate freedom from
            contamination. Section 9.6 describes the required types, procedures, and
            criteria for analysis of blanks.

      9.1.4 Analyses of MS and MSD samples are  required to demonstrate the
            accuracy and  precision of the method and to monitor for matrix
            interferences (Section 9.5). When results of these spikes indicate atypical
            method performance for samples, an alternative extraction or cleanup
            technique must be used to bring method performance within acceptable
            limits.  If method performance cannot be brought within the limits given in
            this method, the result may not be reported for regulatory compliance
            purposes.

      9.1.5 The laboratory shall, on an ongoing  basis, demonstrate through
            calibration verification (Section 9.3) and through analysis of the OPR
            standard (Section 9.7) that the analytical system is meeting the
            performance criteria.

      9.1.6 The laboratory shall maintain records to define the quality of data that are
            generated. Development of accuracy statements is described in Sections
            9.5.5.1 and 9.7.7.

      9.1.7 All samples must be associated with an acceptable OPR, MS/MSD,  IPR,
            and uncontaminated blanks.

9.2   Initial demonstration  of laboratory capability.
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Method 200.7
      9.2.1  Method detection limit-To establish the ability to detect the analyte(s) of
            interest, the analyst shall determine the MDL for each analyte according
            to the procedure in 40 CFR 136, Appendix B using the apparatus,
            reagents, and standards that will be used in the practice of this method.
            The laboratory must produce an MDL that is less than or equal to the
            MDL specified in Table 4 (to be determined by the validation study) or
            one-third the regulatory compliance limit, whichever is greater. MDLs
            must be determined when a new operator begins work or whenever a
            change in instrument hardware or operating conditions is made that may
            affect the MDL. MDLs must be determined for solids with clean sand or
            soil matrix if solid samples are to be run and/or with a reagent water
            matrix if aqueous samples are to be run. MDLs also must be determined
            for biosolids with peat moss if sludge samples are to be analyzed for
            arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium,
            and zinc.

      9.2.2  Initial precision and recovery (IPR)-To establish the ability to generate
            acceptable precision and recovery, the analyst shall perform the following
            operations.

            9.2.2.1       Spike four aliquots of reagent water (for aqueous samples)
                         or clean sand or soil (for solid samples) or peat moss (for
                         biosolid samples) with the analyte(s) of interest at one to
                         five times the ML. Analyze the four aliquots according to the
                         procedures in Section 11.0.  This test must use the
                         containers, labware, and reagents that will be used with
                         samples and all digestion, extraction, and concentrations
                         steps.

            9.2.2.2      Using the results of the four analyses, compute the average
                         percent recovery (X) for the analyte(s) in each aliquot and
                         the standard deviation of the recovery (s) for each analyte.

            9.2.2.3      For each analyte, compare s and X with the corresponding
                         limits for IPR in (Table 5- to be determined in validation
                         study).  If s and X for all analyte(s) meet the acceptance
                         criteria, system performance is acceptable and analysis of
                         blanks and samples may begin.  If, however, any individual
                         s exceeds the precision limit or any individual X falls outside
                         the range for accuracy, system performance is unacceptable
                         for that analyte. Correct the problem and repeat the test.

      9.2.3  Linear dynamic range (LDR)-The upper limit of the LDR must be
            established for each wavelength used.  It must be determined from a
            linear calibration prepared in the normal manner using the established

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                                                                       Method 200.7
            analytical operating procedure for the instrument. The LDR should be
            determined by analyzing successively higher standard concentrations of
            the analyte until the observed analyte concentration is no more than  10%
            below the stated concentration of the standard.  LDRs must be
            documented and kept on file.  The LDR which may be used for the
            analysis of samples should be judged by the analyst from the resulting
            data. Calculated sample analyte concentrations that are greater than
            90% of the determined upper LDR limit must be diluted and analyzed
            again. The LDRs should be verified annually or whenever, in the
            judgement of the analyst, a change in analytical performance caused by
            either a change in instrument hardware or operating conditions would
            dictate they should be redetermined.

      9.2.4 Reference sample-When beginning the use of this method, quarterly, and
            as needed to meet data quality requirements, the analyst must verify the
            calibration standards and acceptable instrument performance with the
            preparation and analysis of a reference sample (Section 7.14). To verify
            the calibration standards, the determined mean concentration from three
            analyses of the reference sample must be within 5% of the stated
            reference sample value. If the reference sample is not within the required
            limits, an immediate second analysis of the reference sample is
            recommended to confirm unacceptable performance. If both the
            calibration standards and acceptable instrument performance cannot be
            verified, the source of the problem must be identified and corrected before
            proceeding with further analyses.

9.3   Calibration verification-A laboratory must analyze a CV solution (Section 7.13)
      and a calibration blank (Section 7.12.1) immediately following daily calibration,
      after every 10th sample (or more  frequently, if required), and at the end of the
      sample run. The analysis data of the calibration blank and CV solution must be
      kept on file with the sample analyses data.

      9.3.1  The result of the calibration blank should be less than the analyte ML or
            one-third the regulatory compliance level, whichever is greater.

      9.3.2 Analysis of the CV solution immediately following calibration must verify
            that the instrument is within performance criteria (to be determined by the
            validation study) (Table 5).

      9.3.3 If the calibration cannot be verified within the specified limits, both the CV
            solution and the calibration blank should  be analyzed again. If the
            second analysis of the CV solution or the calibration blank confirm
            calibration to be outside the limits, sample analysis must be discontinued,
            the cause determined, corrected, and/or the instrument recalibrated.  All
January 2001                              Draft                                     27

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Method 200.7
             samples following the last acceptable CV solution must be analyzed
             again.

9.4    Spectral interference check (SIC) solution-For all determinations the laboratory
       must periodically verify the inter-element spectral interference correction routine
       by analyzing SIC solutions (Section 7.15).

       9.4.1  For interferences from iron and aluminum, only those correction factors
             (positive or negative) which, when multiplied by 100, exceed the analyte
             ML, or one-third the regulatory compliance,  whichever is greater, or fall
             below the lower limit for the calibration blank, need be tested on a daily
             basis. The lower calibration blank control limit is determined by
             subtracting the ML, or one-third the regulatory compliance limit,  whichever
             is greater, from zero.

       9.4.2  For the other interfering elements, only those correction factors  (positive
             or negative) which, when multiplied by 10 to calculate apparent  analyte
             concentrations that exceed the analyte ML,  or one-third the regulatory
             compliance, whichever is greater, or fall below the lower limit for the
             calibration blank, need be tested on a daily  basis.

       9.4.3  If the correction routine is operating properly, the determined apparent
             analyte(s) concentration from analysis of  each interference solution
             (Section 7.15, a through q)  should fall within a specific concentration
             range bracketing the calibration blank.  This concentration range is
             calculated by multiplying the concentration of the interfering element by
             the value of the correction factor being tested and dividing by 10.  If, after
             subtraction of the analyte ML, or one-third the regulatory compliance,
             whichever is greater, the apparent analyte concentration is outside
             (above or below) this range, a change in the correction factor of more
             than 10% should be suspected.  The cause of the change should be
             determined and corrected and the correction factor should be updated.

       NOTE: The SIC solution should be analyzed more than  once to confirm a change has
       occurred, with adequate rinse time between solutions and before subsequent analysis of the
       calibration blank.
      9.4.4  If the correction factors as tested on a daily basis are found to be within
             the 10% criteria for five consecutive days, the required verification
             frequency of those factors in compliance may be extended to a weekly
             basis. Also, if the nature of the samples analyzed is such (e.g., finished
             drinking water) that they do not contain concentrations of the interfering
             elements at the 10 mg/L level, daily verification is not required; however,
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                                                                       Method 200.7
            all inter-element spectral correction factors must be verified annually and
            updated if necessary.

      9.4.5 All inter-element spectral correction factors must be verified whenever
            there is a change in instrument operating conditions. Examples of
            changes requiring rigorous verification of spectral correction factors are:
            changes in incident power, changes in nebulizer gas flow rate, or
            installation of a new torch  injector with a different orifice.

      9.4.6 If the instrument does not  display negative concentration values, fortify
            the SIC solutions with the elements of interest at 1  mg/L and test for
            analyte recoveries that are below 95%.  In the absence of measurable
            analyte, over-correction could go undetected because a negative value
            could be reported as zero.

      9.4.7 For instruments without inter-element correction capability or when inter-
            element corrections are not used, SIC solutions (containing similar
            concentrations of the major components in the samples, e.g., >10 mg/L)
            can serve to verify the absence of effects at the wavelengths selected.
            These data must be kept on file with the sample analysis data. If the SIC
            solution confirms an operative interference that is >10% of the analyte
            concentration, the analyte  must be determined using a wavelength and
            background correction location free of the interference or by another
            approved test procedure.  Users  are advised that high salt concentrations
            can cause  analyte signal suppressions and confuse interference tests.

9.5   Matrix spike (MS) and matrix spike duplicates (MSD)-To assess the performance
      of the method on a given sample  matrix, the laboratory must spike, in duplicate,
      a minimum of 10% (one sample in 10) of the samples from a given sampling site
      or, if for compliance monitoring, from a given discharge. Blanks may not be
      used for MS/MSD analysis.

      9.5.1 The concentration of the MS and MSD shall be determined as follows:

            9.5.1.1       If, as in compliance monitoring, the concentration of
                         analytes in the sample is being checked against a regulatory
                         concentration limit,  the spiking level shall be at that limit or
                         at 1-5 times the background concentration of the sample,
                         whichever is  greater.  (For notes on Ag, Sn, and Ba see
                         Sections 1.7, 1.8, and 1.9).

            9.5.1.2      If the concentration of analytes in a sample is not being
                         checked against a regulatory concentration limit, the spike
                         shall be at 1-5 times the background concentration.


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Method 200.7
             9.5.1.3      For solid and sludge samples, the concentration added
                         should be expressed as mg/kg and is calculated for a one
                         gram aliquot by multiplying the added analyte concentration
                         in solution (mg/L) by the conversion factor 100 (mg/L x
                         0. 1 L/0.001 kg = 1 00, Section 1 2.5). (For notes on Ag, Sn,
                         and  Ba see Sections 1 .7,  1 .8, and 1 .9).

      9.5.2  Assessing spike recovery.

             9.5.2.1      To determine the background concentration (B), analyze
                         one  sample aliquot from each set of 10 samples from each
                         site or discharge according to the  procedure in Section 1 1 .
                         If the expected background concentration is known from
                         previous experience or other knowledge, the spiking level
                         may be established a priori.

      NOTE: The concentrations of calcium, magnesium, sodium and strontium in environmental
      waters, along with iron and aluminum in solids and sludge can vary greatly and are not
      necessarily predictable. Major constituents should not be spiked to >25 mg/L so that the sample
      matrix is not altered and the analysis is not affected. _


             9.5.2.2      Prepare a standard solution to  produce an appropriate
                         concentration in the sample (Section 9.5.1).

             9.5.2.3      Spike two additional sample aliquots with the spiking
                         solution and analyze these aliquots as described in Section
                         1 1 to determine the concentration after spiking (A).

             9.5.2.4      Calculate the percent recovery (P) in each aliquot  (Equation
                         3).

                                    Equation 3

                                          (A-B)
                                          v
                                             T
                   where:
                         P = Percent recovery
                         A = Measured concentration of analyte after spiking
                         B = Measured concentration of analyte before spiking
_ T = True concentration of the spike _

      9.5.3  Compare the percent recovery with the QC acceptance criteria in Table 5
             (to be determined in validation study).

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                                                                        Method 200.7
             9.5.3.1       If P falls outside the designated range for recovery in Table
                         5, the results have failed to meet the established
                         performance criteria. If P is unacceptable, analyze the OPR
                         standard (Section 9.7).  If the OPR is within established
                         performance criteria (Table 5),  the analytical system is
                         within specification and the problem can be attributed to
                         interference by the sample matrix. The data user should be
                         informed that the result for that analyte in the unfortified
                         sample is suspect due to either the heterogeneous nature of
                         the sample or matrix effects,  and analysis by method of
                         standard addition or the use  of an internal standard(s)
                         (Section 11.6) should be considered.

             9.5.3.2       If the results of both the spike and the OPR test fall outside
                         the acceptance criteria, the analytical system is judged to be
                         outside specified limits. The analyst must identify and
                         correct the  problem and analyze the sample batch again.

      9.5.4  Assess the possible need for the method of standard additions (MSA) or
             internal standard elements by the following tests.  Directions for using
             MSA or internal standard(s) are given in Section 11.6.

             9.5.4.1       Analyte addition test: An analyte(s) standard added to a
                         portion of a prepared sample, or its dilution, should have a
                         recovery of 85% to 115% of the known value.  The
                         analyte(s) addition should produce a minimum level of 20
                         times and a maximum level of 100 times the method
                         detection limit.  If the analyte addition is <20% of the sample
                         analyte concentration, the dilution test described in Section
                         9.5.4.2 should be used. If recovery of the analyte(s) is not
                         within the specified limits, a matrix effect should be
                         suspected,  and the associated  data flagged accordingly.
                         The method of additions or the use of an appropriate
                         internal standard element may  provide more accurate data.

             9.5.4.2       Dilution test: If the analyte concentration is sufficiently high
                         (minimally,  a factor of 50 above the instrument detection
                         limit in the original solution but  <90%  of the linear limit), an
                         analysis of  a 1+4 dilution should agree (after correction for
                         the fivefold dilution) within 10% of the original
                         determination.  If not, a chemical or physical interference
                         effect should be suspected and the associated data flagged
                         accordingly. The method of standard additions or the use of
                         an internal-standard element may provide more accurate
                         data for samples failing this test.

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Method 200.7
      9.5.5 Recovery for samples should be assessed and records maintained.

            9.5.5.1      After the analysis of five samples of a given matrix type
                        (river water, biosolids, etc.). For which the analyte(s) pass
                        the tests in Section 9.5.3, compute the  average percent
                        recovery (P) and the standard deviation of the percent
                        recovery (SP) for the analyte(s). Express the accuracy
                        assessment as a percent recovery interval from P - 2SP to P
                        + 2SP for each matrix.  For example, if  P = 90% and SP =
                        10% for five analyses of river water, the accuracy interval is
                        expressed as 70 -110%.

            9.5.5.2      Update the accuracy assessment for each metal in each
                        matrix regularly (e.g., after each five to  ten new
                        measurements).

      9.5.6 Precision of matrix spike and duplicate.

            9.5.6.1      Relative percent difference between duplicates-Compute
                        the relative percent difference (RPD) between the MS and
                        MSD results according to Equation 4 using the
                        concentrations found in the MS and MSD.  Do not use  the
                        recoveries calculated in Section 9.5.2 for this calculation
                        because the RPD is inflated when the background
                        concentration is near the spike concentration.

                                  Equation 4
                              RPD = 200*-

                  where:
                        RPD = Relative percent different
                        D1 = Concentration of the analyte in the MS sample
                        D2 = Concentration of the analyte in the MSD sample
            9.5.6.2      The RPD for the MS/MSD pair must not exceed the
                        acceptance criterion in Table 5 (to be determined in
                        validation study).  If the criterion is not met, the system is
                        judged to be outside accepted limits of performance. The
                        problem must be identified and corrected, and the analytical
                        batch must be analyzed again.
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                                                                      Method 200.7
            9.5.6.3       Reference material analysis can provide additional
                         interference data.  The analysis of reference samples is a
                         valuable tool for demonstrating the ability to perform the
                         method acceptably. Reference materials containing high
                         concentrations of analytes can provide additional
                         information on the performance of the spectral interference
                         correction routine.

9.6   Blanks.

      9.6.1  Method blank.

            9.6.1.1       Prepare a method blank with each sample batch (samples of
                         the same matrix - reagent water for aqueous samples, clean
                         sand or soil for solid samples, peat moss for biosolid
                         samples) started through the sample preparation process
                         (Section 11.0) on the same 12-hour shift, to a maximum of
                         20 samples). Analyze the blank immediately after the OPR
                         is analyzed (Section 9.7) to demonstrate freedom from
                         contamination.

            9.6.1.2       If the analyte(s)  of interest or any potentially interfering
                         substance is found in the method blank at a concentration
                         equal to or greater than the ML (Table 4, to be determined
                         by the validation study) or 1/3 the regulatory compliance
                         level, whichever is greater, sample analysis must be halted,
                         the source of the contamination determined, the samples
                         must be prepared again with a fresh method blank and  OPR
                         and analyzed again.

            9.6.1.3       Alternatively, if a sufficient number of blanks (three
                         minimum) are analyzed to characterize the nature of a
                         blank,  the average concentration plus two standard
                         deviations  must  be less than the regulatory compliance
                         level.

            9.6.1.4       If the result for a single blank remains above the ML or if the
                         result for the average concentration plus two standard
                         deviations  of three or more blanks exceeds the regulatory
                         compliance level, results for samples associated with those
                         blanks may not be reported for regulatory compliance
                         purposes.

      9.6.2  Field blank.


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Method 200.7
            9.6.2.1      Analyze the field blank(s) shipped with each set of samples
                        (samples collected from the same site at the same time, to a
                        maximum of 20 samples).  Analyze the blank immediately
                        before analyzing the samples in the batch.

            9.6.2.2      If the analyte(s) of interest or any potentially interfering
                        substance is found in the field blank at a concentration
                        equal to or greater than the ML or greater than one-fifth the
                        level in the associated sample, whichever is greater, results
                        for associated samples may be the result of contamination
                        and may not be reported for regulatory compliance
                        purposes.

            9.6.2.3      Alternatively, if a sufficient number of field blanks (three
                        minimum) are analyzed to characterize the nature of the
                        field blank, the average concentration plus two standard
                        deviations must be less than the regulatory compliance level
                        or less than one-half the level in the associated sample,
                        whichever is greater.

            9.6.2.4      If contamination of the field blanks and associated samples
                        is known or suspected, the laboratory should communicate
                        this to the sampling team so that the source of
                        contamination can be identified and corrective measures
                        taken prior to the next sampling event.

      9.6.3 Equipment blanks-Before any sampling equipment is used at a given site,
            it is recommended that the laboratory or cleaning facility generate
            equipment blanks to demonstrate that the sampling equipment is free
            from contamination. Two types of equipment blanks are recommended:
            bottle blanks and sampler check blanks.

            9.6.3.1      Bottle blanks-After undergoing appropriate cleaning
                        procedures (Section 6.10), bottles should be subjected to
                        conditions of use to verify the effectiveness of the cleaning
                        procedures. A representative set of sample bottles should
                        be filled with reagent water acidified to pH < 2 and allowed
                        to stand for a minimum of 24 hours. Ideally, the time that
                        the bottles are allowed to stand should be as close as
                        possible to the actual time that sample will be in contact with
                        the bottle.  After standing,  the water should be analyzed for
                        any signs of contamination.  If any bottle shows signs of
                        contamination, the problem must be identified, the cleaning
                        procedures corrected or cleaning solutions changed, and all
                        affected bottles cleaned again.

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                                                                      Method 200.7
            9.6.3.2      Sampler check blanks-Sampler check blanks are generated
                        in the laboratory or at the equipment cleaning contractor's
                        facility by processing reagent water through the sampling
                        devices using the same procedures that are used in the
                        field.

                  9.6.3.2.1    Sampler check blanks are generated by filling a large
                              carboy or other container with reagent water (Section
                              7.1) and processing the reagent water through the
                              equipment using the same procedures that are used
                              in the field. For example, manual grab sampler check
                              blanks are collected by directly submerging a sample
                              bottle into the water, filling the bottle, and capping.
                              Subsurface sampler check blanks are collected by
                              immersing the sampler into the water and pumping
                              water into a sample container. Whatever precautions
                              and equipment are used in the field should also be
                              used to generate these blanks.

                  9.6.3.2.2    The sampler check blank should be analyzed using
                              the procedures in this method. If the target analyte(s)
                              or any potentially interfering substance is detected in
                              the blank, the source of contamination or interference
                              must be identified and the problem corrected.  The
                              equipment should be demonstrated to be free from
                              contamination before the equipment is used in the
                              field.

                  9.6.3.2.3    Sampler check blanks should be run on all equipment
                              that will be used  in the field.   If, for example, samples
                              are to be collected using both a grab sampling device
                              and a subsurface sampling device, a sampler check
                              blank must be run on both pieces of equipment.

9.7   Ongoing precision and recovery.

      9.7.1  For aqueous samples, prepare an OPR sample (laboratory fortified
            method blank) identical to the IPR aliquots (Section 9.2.2.1) with each
            preparation batch (samples of the same  matrix started through the sample
            preparation process (Section  11.0) on the same  12-hour shift, to a
            maximum of 20 samples) by spiking an aliquot of reagent water with the
            analyte(s) of interest.

      9.7.2  For solid samples, the use of clean sand or soil fortified as in Section
            9.7.1 is recommended.

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Method 200.7
      9.7.3 For biosolid samples, the use of peat moss fortified as in Section 9.7.1 is
            recommended.

      9.7.4 Analyze the OPR sample immediately before the method blank and
            samples from the same batch.

      9.7.5 Compute the percent recovery of each analyte in the OPR sample.

      9.7.6 For each analyte, compare the concentration to the limits for ongoing
            recovery in (Table 5 - to be determined in validation study).  If all
            analyte(s) meet the acceptance criteria, system performance is
            acceptable and analysis of blanks and samples may proceed. If,
            however, any individual recovery falls outside of the range given, the
            analytical processes are not being performed properly for that analyte.
            Correct the problem, prepare the sample batch again with fresh OPR and
            method blank, and reanalyze the QA/QC and samples.

      9.7.7 Add results that pass the specifications in Section 9.7.6 to IPR and
            previous OPR data for each analyte in each matrix. Update QC charts to
            form a graphic representation of continued laboratory performance.
            Develop a statement of laboratory accuracy for each analyte in each
            matrix type by calculating the average percent recovery (P) and the
            standard deviation of percent recovery (SP). Express the accuracy as a
            recovery interval from P - 2SP to P + 2SP.  For example, if P = 95% and
            SP = 5%, the accuracy is 85 -105%.

10.0 Calibration and Standardization

10.1  For initial and daily operation, calibrate the instrument according to the
      instrument manufacturer's recommended procedures, using mixed  calibration
      standard solutions (Section 7.11).

10.2  The  calibration line should include at least three non-zero points with the high
      standard near the upper limit of the linear dynamic range (Section 9.2.3) and the
      low standard that contains the analyte(s) of interest at the ML (Section 1.12,
      Table 4, to be determined during the validation study). Replicates  of a
      calibration blank (Section 7.13.1) and the highest standard provide an optimal
      distribution of calibration standards to minimize  the confidence band for a
      straight-line calibration in a response region with uniform variance  (Reference
      20).

10.3  Calculate the slope and intercept of a line using weighted linear regression. Use
      the inverse of the standard's concentration squared (1/x2) as the weighting
      factor. The calibration is acceptable if the R2 is  greater than 0.995 and the
      absolute value of the intercept is less than the MDL for the target analyte.  If
36                                     Draft                               January 2001

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                                                                        Method 200.7
      these conditions are not met, then the laboratory may not report data analyzed
      under that calibration and must recalibrate the instrument.

10.4  The concentration of samples is determined using Equation 5.

                                   Equation 5

                                   y = mx + b

                   where       y = sample concentration
                         m = slope (calculated In Section 10.3)
                         x = instrument response
_ b = Intercept (calculated In Section 10.3) _

1 0.5  Response factor may be calculated as an alternative to weighted linear regression for
      instrument calibration. Calculate the response factor (RF) at each concentration, as
      follows:

                                   Equation 6
                   where:
                         Rx = Peak height or area
                         Cy = Concentration of standard x
                          -X
      10.5.1 Calculate the mean response factor (RFJ, the standard deviation of the
             RFm, and the relative standard deviation (RSD) of the mean (Equation 7).

                                   Equation 7
                                             SD
                                RSD= 100*-
                   where:
                         RSD = Relative standard deviation of the mean
                         SD = Standard deviation of the RFm
                  	RFm = the mean response factor	
      10.5.2 Performance criteria for the calibration will be calculated after the
             validation of the method.
January 2001                             Draft                                     37

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Method 200.7
11.0 Procedure

11.1  Aqueous sample preparation (Dissolved analytes)-For the determination of
      dissolved analytes in ground, drinking and surface waters, pipet an aliquot (>20
      ml) of the filtered, acid preserved sample into a 50-mL polypropylene centrifuge
      tube. Add an appropriate volume of (1 +1)  HN03 to adjust the acid concentration
      of the aliquot to approximate a 1% (v/v) HN03 solution (e.g., add 0.2 ml (1+1)
      HN03 to a 20 ml aliquot of sample).  Cap the tube and mix. The sample is now
      ready for analysis. Allowance for sample dilution should be made in the
      calculations (Section 12).  If mercury is to be determined, a separate aliquot
      must be additionally acidified to contain 1% (v/v) HCI to match the signal
      response of mercury in the calibration standard and reduce memory interference
      effects.

      NOTE: If a precipitate is formed during acidification, transport,  or storage,  the sample aliquot
      must be treated using the procedure described in Sections 11.2.2 through 11.2.7 prior to
	analysis.	


11.2  Aqueous Sample Preparation-Total Recoverable Analytes

      11.2.1  For the "direct analysis" of total recoverable analytes in drinking water
             samples containing turbidity <1 NTU, treat an unfiltered, acid preserved
             sample aliquot using the sample preparation procedure described in
             Section 11.1 while making allowance for sample dilution in the data
             calculation (Section  12.0).  For the determination of total recoverable
             analytes in all other aqueous samples or for preconcentrating drinking
             water samples prior  to analysis, follow the procedure given  in
             Sections 11.2.2 through 11.2.7.

      11.2.2 For the determination of total recoverable analytes in aqueous samples of
             >1  NTU turbidity, transfer a 100 ml  (1 ml) aliquot from a well mixed,
             acid preserved sample to a 250-mL Griffin beaker. (When necessary,
             smaller sample aliquot volumes may be used).

      NOTE: If the sample contains  undissolved solids >1%, a well mixed, acid preserved aliquot
      containing no more than 1 gparticulate material should be cautiously evaporated to near 10 mL
	and extracted using the acid-mixture procedure described in Sections 11.3.3 through 11.3.6.


      11.2.3 Add 2 mL (1+1) HN03 and 1.0 mL of (1+1) HCI to the beaker containing
             the measured volume of sample.  Place the beaker on the hot plate for
             solution evaporation. The hot plate should be located in a fume hood and
             previously adjusted to provide evaporation at a temperature of
             approximately but  no higher than 85C.  (See the following  note).  The
             beaker should be covered with an elevated  watch glass or other
38                                     Draft                               January2001

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                                                                        Method 200.7
             necessary steps should be taken to prevent sample contamination from
             the fume hood environment.

      NOTE: For proper heating, adjust the temperature control of the hot plate such that an
      uncovered Griffin beaker containing 50 mL of water placed in the center of the hot plate can be
      maintained at a temperature approximately but no higher than 85C. (Once the beaker is
	covered with a watch glass, the temperature of the water will rise to approximately 95 C).	


      11.2.4 Reduce the volume of the sample aliquot to about 20  mL by gentle
             heating at 85C.  DO NOT BOIL.  This step takes about two hours for a
             100 mL aliquot with the rate of evaporation rapidly increasing as the
             sample volume approaches 20 mL. (A spare beaker containing 20 mL of
             water can be used as a gauge).

      11.2.5 Cover the  lip of the beaker with a watch glass to reduce additional
             evaporation and gently reflux the sample for 30 minutes. (Slight boiling
             may occur, but vigorous boiling must be avoided to prevent loss of the
             HCI-H20 azeotrope).

      11.2.6 Allow the beaker to cool. Quantitatively transfer the sample solution to a
             50-mL volumetric flask, dilute to volume with reagent water, stopper and
             mix.

      11.2.7 Allow any undissolved material to settle overnight, or  centrifuge a portion
             of the prepared sample until clear. (If after centrifuging or standing
             overnight, the sample contains suspended solids that would clog the
             nebulizer, a portion of the sample may be filtered for their removal prior to
             analysis.  However, care should be exercised to avoid potential
             contamination from filtration). 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.

11.3  Solid sample preparation-Total recoverable analytes

      11.3.1 For the determination of total recoverable analytes in  solid  samples,  mix
             the sample thoroughly and transfer a portion to a tared weighing dish.
             For samples with <35% estimated  moisture, a 20 g portion  is sufficient.
             For samples with estimated moisture >35%, a larger aliquot 50-100 g is
             required.  Dry the sample to a constant weight at 60C. The  sample is
             dried at 60C to prevent the loss of mercury and other possible volatile
             metallic compounds, to facilitate sieving, and to ready the sample for
             grinding.
January 2001                             Draft                                     39

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Method 200.7
       11.3.2 To achieve homogeneity, sieve the dried sample using a 5-mesh
             polypropylene sieve and grind in a mortar and pestle.  (The sieve, mortar
             and pestle should be cleaned between samples).  From the dried, ground
             material weigh accurately a representative 1.0  0.01 g aliquot (W) of the
             sample and transfer to a 250-mL Phillips beaker for acid extraction
             (Sections 1.6, 1.7,  1.8, and 1.9).

       11.3.3 To the beaker, add 4 ml of (1+1) HN03 and 10  ml of (1+4) HCI. Cover
             the lip of the beaker with a watch glass. Place the beaker on a hot plate
             for reflux extraction of the analytes.  The hot plate should be located  in a
             fume hood  and previously adjusted to provide a reflux temperature of
             approximately 95C (See the following note).

       NOTE: For proper heating, adjust the temperature control of the hot plate such that an
       uncovered Griffin beaker containing 50 mL of water placed in the center of the hot plate can be
       maintained at a temperature approximately but no higher than 85C. (Once the beaker is
       covered with a  watch glass the temperature of the water will rise to approximately 95 C). Also,
       a block digester capable of maintaining a temperature of95C and equipped with 250 mL
       constricted volumetric digestion tubes may be substituted for the hot plate and conical beakers in
	the extraction step.	


       11.3.4 Heat the sample and gently reflux for 30 minutes.  Very slight boiling  may
             occur, but vigorous boiling must be avoided to prevent loss of the HCI-
             H20 azeotrope. Some solution evaporation will  occur (3-4 mL).

       11.3.5 Allow  the sample to cool and quantitatively transfer the extract to a 100-
             ml_ volumetric flask.  Dilute to volume with reagent water, stopper and
             mix.

       11.3.6 Allow  the sample extract solution to stand overnight to separate insoluble
             material or centrifuge a portion of the sample solution  until clear.  (If after
             centrifuging or standing overnight, the extract solution contains
             suspended solids that would clog the nebulizer, a portion of the extract
             solution may  be filtered for their removal prior to analysis.  However, care
             should be exercised to avoid potential contamination from filtration).  The
             sample extract 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.

       11.3.7 Determine the total solids content of the sample using the procedure in
             Appendix A.

11.4   Sludge sample preparation-Total recoverable analytes.

40                                      Draft                                January 2001

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                                                                        Method 200.7
      NOTE: It may be possible to use the solids digestion (Section 11.3) for sludge samples,
      depending on the composition of the sludge sample and the analyte(s) of interest.  Under this
      performance-based method, it is admissible to change the digestion technique as long as all
      quality control and assurance tests meet the criteria published in Tables 4 and 5.  This method
      has been validated using the sludge sample digestion in Section 11.4 of this method, and it works
      for all the analytes listed in Section 1.1.	


      11.4.1 Determination of total recoverable analytes in sludge samples containing
             total suspended solids >1% (w/v).

             11.4.1.1     Mix the sample thoroughly and transfer a portion to a tared
                         weighing dish. For samples with <35% estimated moisture a
                         20 g portion is sufficient.  For samples with estimated
                         moisture >35% a larger aliquot of 50-100 g is required.  Dry
                         the sample to a constant weight at 60C.  The sample is
                         dried at 60C to  prevent the loss of mercury and other
                         possible volatile  metallic compounds, to facilitate sieving,
                         and to  ready the sample for grinding.

             11.4.1.2     To achieve homogeneity, sieve the dried sample using a 5-
                         mesh polypropylene sieve and grind in a mortar and pestle.
                         (The sieve, mortar and pestle should be cleaned between
                         samples).  From the dried, ground material weigh accurately
                         a representative 1.0  0.01  g aliquot (W) of the sample and
                         transfer to a 250-mL Phillips beaker for acid extraction
                         (Sections 1.6,  1.7, 1.8, and 1.9).

             11.4.1.3     Add 10 ml of (1 +1)  HN03 to the beaker and cover the lip of
                         the beaker with a watch  glass. Place the beaker on a hot
                         plate and reflux the  sample for 10 minutes.  Remove the
                         sample from the hot plate and allow to cool. Add 5 ml of
                         concentrated HN03 to the beaker, replace the watch glass,
                         place on a hot plate, and reflux for 30 minutes.  Repeat this
                         last step once. Remove the beaker from the hot plate and
                         allow the sample to  cool. Add 2 ml of reagent water and 3
                         ml of 30% H202.  Place the beaker on a hot plate and heat
                         the sample until a gentle effervescence is observed.  Once
                         the reaction has subsided, additional 1 ml aliquots of the
                         30% H202 should be added until no effervescence is
                         observed, but to no  more than a total of 10 ml.  Add 2 ml
                         concentrated HCI and 10 ml of reagent water to the sample,
                         cover with a watch glass and reflux for 15 minutes.
January 2001                              Draft                                     41

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Method 200.7
            11.4.1.4     Cool the sample and dilute to 100 ml with reagent water.
                        Any remaining solid material should be allowed to settle, or
                        an aliquot of the final sample volume may be centrifuged.

            11.4.1.5     Determine the total solids content of the sample using the
                        procedure in Appendix A.

      11.4.2 Determination of total recoverable analytes in sludge samples containing
            total suspended solids < 1% (w/v).

            11.4.2.1     Transfer 100 ml of well-mixed sample to a 250-mL Griffin
                        beaker.

            11.4.2.2     Add 3 ml of concentrated HN03 and place the beaker on a
                        hot plate. Heat the sample and cautiously evaporate to a
                        volume of 5 ml. If the sample contains large amounts of
                        dissolved solids, adjust this volume upwards to prevent the
                        sample from going to dryness. Remove the beaker from the
                        hot plate and allow the sample to cool. Add 3 ml of
                        concentrated HN03, cover with a watch glass and gently
                        reflux the sample until the sample is completely digested or
                        no further changes in appearance occur, adding additional
                        aliquots of acid if necessary to prevent the sample from
                        going to dryness.  Then remove the watch glass and reduce
                        the sample volume to 3 ml, again adjusting upwards if
                        necessary.

            11.4.2.3     Cool the beaker, then add 10 m L of reagent water and 4 m L
                        of (1 +1) HCI to the sample and reflux for 15 minutes.  Cool
                        the sample and dilute to 100 ml with reagent water. Any
                        remaining solid material should be allowed to settle, or an
                        aliquot of the final  sample volume may be centrifuged.

            11.4.2.4     Determine the total solids content of the sample using the
                        procedure in Appendix A.

11.5  Sample analysis.

      11.5.1 Prior to daily calibration of the instrument, inspect the sample introduction
            system including the nebulizer, torch, injector tube and uptake tubing for
            salt deposits, dirt and debris that would restrict solution flow and affect
            instrument performance.  Clean the system when needed or on a daily
            basis.

      11.5.2 Configure the instrument system.
42                                     Draft                             January 2001

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                                                                      Method 200.7
            11.5.2.1     Specific wavelengths are listed in Table 1.  Other
                        wavelengths may be substituted if they can provide the
                        needed sensitivity and are corrected for spectral
                        interference. However, because of the difference among
                        various makes and models of spectrometers, specific
                        instrument operating conditions cannot be given. The
                        instrument and operating conditions utilized for
                        determination must be capable of providing data of
                        acceptable quality to the program and data user. The
                        analyst should follow the instructions provided by the
                        instrument manufacturer unless other conditions provide
                        similar or better performance for a task. Operating
                        conditions for aqueous solutions usually vary from 1100 -
                        1200 watts forward power, 15-16 mm viewing height, 15 -
                        19 L/min. argon coolant flow, 0.6 -1 L/min. argon aerosol
                        flow, 1-1.8 mL/min. sample pumping rate with a one minute
                        preflush time and measurement time near 1 s per
                        wavelength peak (for sequential instruments) and near 10 s
                        per sample (for simultaneous instruments). Use of the
                        Cu/Mn intensity ratio at 324.754 nm and 257.610 nm  (by
                        adjusting the argon aerosol flow) has been recommended as
                        a way to achieve repeatable interference correction factors
                        (Reference 17).

            11.5.2.2     Prior to using this method, optimize the plasma operating
                        conditions. The  following procedure  is recommended for
                        vertically configured plasmas. 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.

            11.5.2.3     Ignite the plasma and select an appropriate incident rf
                        power with minimum reflected power.  Allow the instrument
                        to become thermally stable before beginning. This usually
                        requires  at least 30 to  60 minutes of operation.  While
                        aspirating the 1000 ug/mL solution of yttrium
                        (Section  7.10.32), follow the instrument manufacturer's
                        instructions and  adjust the aerosol carrier gas flow rate
                        through the nebulizer so a definitive blue emission region of
                        the plasma extends  approximately from 5-20 mm above the
                        top of the work coil (Reference  18).  Record the nebulizer
                        gas flow rate or pressure setting for future reference.
January 2001                              Draft                                    43

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Method 200.7
             11.5.2.4     After establishing the nebulizer gas flow rate, determine the
                         solution uptake rate of the nebulizer in mL/min. by aspirating
                         a known volume  calibration blank for a period of at least
                         three minutes. Divide the spent volume by the aspiration
                         time (in minutes) and record the uptake rate.  Set the
                         peristaltic pump to deliver the uptake rate in a steady even
                         flow.

             11.5.2.5     After horizontally aligning the plasma and/or optically
                         profiling the spectrometer, use the selected instrument
                         conditions from Sections 11.5.2.3 and 11.5.2.4, and aspirate
                         the plasma solution  (Section 7.16), containing 10  ug/mL
                         each of As, Pb, Se and Tl. Collect intensity data at the
                         wavelength peak for each analyte  at 1 mm intervals from 14
                         -18 mm above the top of the work coil. This region of the
                         plasma is commonly referred to  as the analytical zone
                         (Reference 19).  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 highest net intensity for
                         the least sensitive element or accept a compromise position
                         of the intensity ratios of all four analytes.

             11.5.2.6     The instrument operating condition finally selected as
                         optimum should provide the lowest reliable method
                         detection limits.

             11.5.2.7     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.

             11.5.2.8     Before daily calibration and after the instrument warmup
                         period, the nebulizer gas flow must be reset to the
                         determined optimized flow.  If a  mass flow controller is being
                         used,  it should be reset to the recorded optimized flow rate.
                         In  order to maintain  valid spectral inter-element correction
                         routines, the nebulizer gas flow  rate should be the same
                         from day-to-day (<2% change).  The change in signal
                         intensity with a change in nebulizer gas flow rate for both
44                                     Draft                               January 2001

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                                                                      Method 200.7
                        "hard" (Pb 220.353 nm) and "soft" (Cu 324.754) lines is
                        illustrated in Figure 1.

      11.5.3 The instrument must be allowed to become thermally stable before
            calibration and analyses.  This usually requires at least 30 to 60 minutes
            of operation. After instrument warmup, complete any required optical
            profiling or alignment particular to the instrument.

      11.5.4 Prior to and during the analysis of samples, the laboratory must comply
            with the required QA/QC procedures (Section 9).  QA/QC data must be
            generated using the same instrument operating conditions (Section 11.5)
            and calibration routine (Section 10) in effect for sample analysis. The
            data must be documented and kept on file so that they are available for
            review by the data user.

      11.5.5 A peristaltic pump must be used to introduce all solutions to the nebulizer.
            To allow equilibrium to be reached in the plasma, aspirate all solutions for
            30 seconds after reaching the plasma before beginning integration of the
            background corrected signal to accumulate data. When possible, use the
            average value of replicate integration periods of the signal to be
            correlated to the analyte concentration.  Flush the system with the rinse
            blank (Section 7.12.1) fora minimum of 60 seconds (Section 4.4) between
            all standard or sample solutions, OPRs,  MS, MSD, and check solutions.

      11.5.6 Determined sample analyte concentrations that are 90% or more of the
            upper limit of the analyte LDR must be diluted with reagent water that has
            been acidified  in the same manner as calibration  blank and analyzed
            again.

      11.5.7 Also, for the inter-element spectral interference correction routines to
            remain valid during sample analysis, the interferant concentration must
            not exceed its  LDR. If the interferant LDR is exceeded, analyte detection
            limits are raised and determination by another approved test procedure
            that is either more sensitive and/or interference free is  recommended.  If
            another approved method is unavailable, the sample may be diluted with
            acidified reagent water and  reanalyzed.

      11.5.8 When it is necessary to assess an operative matrix interference (e.g.,
            signal reduction due to high dissolved solids), the tests described in
            Section 9.5.4 and 11.6 are recommended.

      11.5.9 Report data as directed in Section 12.0.

11.6  If the method of standard additions (MSA) is used, standards  are added at one
      or more levels to portions of a prepared sample.  This technique compensates

January 2001                             Draft                                    ~5

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Method 200.7
      for enhancement or depression of an analyte signal by a matrix (Reference 21).
      It will not correct for additive interferences such as contamination, inter-element
      interferences, or baseline shifts. This technique is valid in the linear range when
      the interference effect is constant over the range, the added analyte responds
      the same as the endogenous analyte, and the signal is corrected for additive
      interferences.  The simplest version of this technique is the single-addition
      method.  This procedure calls for two identical aliquots of the sample solution to
      be taken. To the first aliquot, a small volume of standard is added; while to the
      second aliquot, a volume of acid blank is added equal to the standard addition.
      The sample concentration is calculated with  Equation 8.

                                  Equation 8
                                 s~
                                    (Sl-s2)*v2
                  where:
                        Cs = Sample concentration (mg/L)
                        C = Concentration of the standard solution (mg/L)
                        S1 = Signal for fortified aliquot
                        S2 = Signal for unfortified aliquot
                        V1 = Volume of the standard addition (L)
_ Vy = Volume of the sample aliquot (L) used for MSA _

      For more than one fortified portion of the prepared sample, linear regression
      analysis can be applied using a computer or calculator program to  obtain the
      concentration of the sample solution.  An alternative to using the method of
      standard additions is  use of the internal  standard technique by adding one or
      more elements (not in the samples and verified not to cause an uncorrected
      inter-element spectral interference) at the same concentration (which is sufficient
      for optimum precision) to the prepared samples (blanks and standards) that are
      affected the same as the analytes by the sample matrix.  Use the ratio of analyte
      signal to the internal standard signal for calibration and quantitation.

12.0 Data Analysis and Calculations

12.1  Sample data should be reported in units of mg/L for aqueous samples and  mg/kg
      dry weight for solid and sludge  samples.

1 2.2  For dissolved aqueous analytes (Section 11.1) report the data generated directly
      from the instrument with allowance for sample dilution.  Do not report analyte
      concentrations below the MDL.

12.3  For total recoverable  aqueous analytes (Section 1 1 .2), multiply solution analyte
      concentrations by the dilution factor 0.5, when 100 ml aliquot is used to produce

46                                     Draft                               January 2001

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                                                                      Method 200.7
      the 50 mL final solution, and report data as instructed in Section 12.4.  If an
      aliquot volume other than 100 mL is used for sample preparation, adjust the
      dilution factor accordingly. Also, account for any additional dilution of the
      prepared sample solution needed to complete the determination of analytes
      exceeding 90% or more of the LDR upper limit.  Do not report data below the
      determined analyte MDL concentration.

12.4  For analytes with MDLs <0.01 mg/L, round the data values to the thousandth
      place and report analyte concentrations up to three significant figures.  For
      analytes with MDLs >0.01 mg/L, round the data values to the hundredth place
      and report analyte concentrations up to three significant figures.  Extract
      concentrations for solids and sludge data should be rounded in a similar manner
      before calculations in Section 12.5 are performed.

12.5  For total recoverable analytes in solid and sludge samples (Sections 11.3 and
      11.4), round the solution analyte concentrations (mg/L) as instructed in Section
      12.4.  Report the data up to three significant figures as mg/kg dry-weight basis
      unless specified otherwise by the program or data user. Calculate the
      concentration using Equation 9.

                                  Equation 9

                                      C*V*D
                                  s~    W
                  where:
                        Cs=Sample concentration (mg/kg, dry-weight basis)
                        C=Concentration in extract (mg/L)
                        V=Volume of extract (L,  100 mL = 0.1L)
                        D=Dilution factor (undiluted  = 1)
	W=Dry weight of sample aliquot extracted (kg, 1g = 0.001kg)

      Do not report analyte data below the solids MDL.

12.6  To report percent solids or mg/kg of solid and sludge samples, use the
      procedure in Appendix A.

12.7  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.

13.0  Method Performance

13.1  MDLs and MLs will be determined in a validation study.  Preliminary MDL values
      are given in Table 4. The ML for each analyte can be calculated by multiplying
January 2001                              Draft                                    47

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Method 200.7
      the MDL by 3.18 and rounding to the number nearest (2, 5, or 10 X 10") where n
      is a positive or negative integer.

14.0  Pollution Prevention

14.1  Pollution prevention encompasses any technique that reduces or eliminates the
      quantity or toxicity of waste at the point of generation. Numerous opportunities
      for pollution prevention exist in laboratory operation. The EPA has established a
      preferred hierarchy of environmental management techniques that places
      pollution prevention as the management option of first choice.  Whenever
      feasible, laboratory personnel should use pollution prevention techniques to
      address their waste generation (e.g., Section 7.10).  When wastes cannot be
      feasibly reduced at the source, the Agency recommends recycling as the next
      best option.

14.2  For information about pollution prevention that may be applicable to laboratories
      and research institutions, consult "Less is Better: Laboratory Chemical
      Management for Waste Reduction," available from the American Chemical
      Society's Department of Government Relations and Science Policy, 1155 16th
      Street N.W.,  Washington, D.C. 20036, (202) 872-4477.

15.0  Waste Management

15.1  The Environmental Protection Agency requires that laboratory waste
      management practices be conducted consistent with all applicable rules and
      regulations.  The Agency urges laboratories  to protect the air, water, and land by
      minimizing and controlling all releases from hoods and bench operations,
      complying with the letter and spirit of any sewer discharge permits and
      regulations, and by complying with all solid and hazardous waste regulations,
      particularly the hazardous waste  identification rules and land disposal
      restrictions.  For further information on waste management consult "The Waste
      Management Manual for Laboratory Personnel," available from the American
      Chemical Society at the address  listed in the Section 14.2.

16.0  References

1.    U.S. Environmental Protection Agency.  Inductively Coupled Plasma-Atomic
      Emission Spectrometric Method for Trace Element Analysis of Water and
      Wastes-Method 200.7, Dec. 1982. EPA-600/4-79-020, revised March 1983.

2.    U.S. Environmental Protection Agency.  Inductively Coupled Plasma Atomic
      Emission Spectroscopy Method 6010, SW-846 Test Methods for Evaluating
      Solid Waste, 3rd Edition, 1986.
48                                    Draft                              January 2001

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                                                                    Method 200.7
3.     U.S. Environmental Protection Agency. Method 200.7: Determination of Metals
      and Trace Elements in Water and Wastes by Inductively Coupled Plasma-
      Atomic Emission Spectrometry, revision 3.3, EPA 600 4-91/010 June 1991.

4.     U.S. Environmental Protection Agency. Inductively Coupled Plasma-Atomic
      Emission Spectrometry Method for the Analysis of Waters and Solids, EMMC,
      July 1992.

5.     Fassel, V.A. et al.  Simultaneous Determination of Wear Metals in Lubricating
      Oils by Inductively-Coupled Plasma Atomic Emission Spectrometry. Anal.
      Chem. 48:516-519, 1976.

6.     Merryfield, R.N. and R.C. Loyd.  Simultaneous  Determination of Metals in Oil by
      Inductively Coupled Plasma Emission Spectrometry. Anal. Chem. 51:1965-1968,
      1979.

7.     Winge, R.K. etal.  Inductively Coupled Plasma-Atomic Emission Spectroscopy:
      An Atlas of Spectral Information, Physical Science Data 20. Elsevier Science
      Publishing, New York, New York, 1985.

8.     Boumans, P.W.J.M.  Line Coincidence Tables for Inductively Coupled Plasma
      Atomic Emission Spectrometry, 2nd edition. Pergamon Press, Oxford, United
      Kingdom, 1984.

9.     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. Available
      from the National Technical Information Service (NTIS) as PB-277256.

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

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

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

13.   Rohrbough, W.G. et al.  Reagent Chemicals, American Chemical Society
      Specifications,  7th edition. American Chemical Society, Washington, D.C.,
      1986.
January 2001                             Draft                                   49

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Method 200.7
14.   American Society for Testing and Materials.  Standard Specification for Reagent
      Water, D1193-77.  Annual Book of ASTM Standards, Vol. 11.01.  Philadelphia,
      PA, 1991.

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

16.   Maxfield, R. and B. Mindak. EPA Method Study 27, Method 200.7 Trace Metals
      by ICP, Nov. 1983. Available from National Technical Information Service
      (NTIS) as PB 85-248-656.

17.   Botto, R.I.,  Quality Assurance in Operating a Multielement ICP Emission
      Spectrometer.  Spectrochim. Acta, 39B(1):95-113,  1984.

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

19.   Koirtyohann, S.R. et al.  Nomenclature System for the Low-Power Argon
      Inductively Coupled Plasma, Anal. Chem. 52:1965, 1980.

20.   Deming, S.N. and S.L. Morgan.  Experimental Design for Quality and
      Productivity in Research, Development, and Manufacturing, Part III, pp 119-123.
      Short course publication by Statistical Designs, 9941 Rowlett, Suite 6, Houston,
      TX 77075, 1989.

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

22.   Jones, C.L. et al. An Interlaboratory Study of Inductively Coupled Plasma
      Atomic Emission Spectroscopy Method 6010 and Digestion Method 3050.  EPA-
      600/4-87-032, U.S. Environmental Protection Agency, Las Vegas, Nevada,
      1987.

23.   Martin, T.D., E.R. Martin and S.E. Long. Method 200.2:  Sample Preparation
      Procedure for Spectrochemical Analyses of Total Recoverable Elements,  EMSL
      ORD, USEPA,  1989.

24.   Handbook of Analytical Quality Control in Water and Wastewater Laboratories]
      U.S. Environmental Protection Agency. EMSL-Cincinnati, OH, March 1979.
50                                    Draft                             January 2001

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                                                                                               Method 200.7
17.0 Tables, Diagrams, Flowcharts, and Validation Data
TABLE 1: WAVELENGTHS, ESTIMATED INSTRUMENT DETECTION
LIMITS,



Analyte
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Cerium
Chromium
Cobalt
Copper
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Phosphorus
Potassium
Selenium
Silica (Si02)
Silver
Sodium
Strontium
Thallium
Tin
Titanium
Vanadium
Zinc

AND RECOMMENDED


Wavelength3
(nm)
308.215
206.833
193.759
493.409
313.042
249.678
226.502
315.887
413.765
205.552
228.616
324.754
259.940
220.353
670.784
279.079
257.610
194.227
203.844
231.604
214.914
766.491
196.090
251.611
328.068
588.995
421.552
190.864
189.980
334.941
292.402
213.856
CALIBRATION
Estimated
Detection
Limit"
(M9/L)
45
32
53
2.3
0.27
5.7
3.4
30
48
6.1
7.0
5.4
6.2
42
3.7d
30
1.4
2.5
12
15
76
700e
75
26d (Si02)
7.0
29
0.77
40
25
3.8
7.5
1.8


Calibrate0
to
(mg/L)
10
5
10
1
1
1
2
10
2
5
2
2
10
10
5
10
2
2
10
2
10
20
5
10
0.5
10
1
5
4
10
2
5
January 2001
Draft
51

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Method 200.7
      aThe wavelengths listed are recommended because of their sensitivity and
      overall acceptability. Other wavelengths may be substituted if they can provide
      the needed sensitivity and are treated with the same corrective techniques for
      spectral interference (see Section 4.1).
      bThese estimated 3-sigma instrumental detection limits are provided only as a
      guide to instrumental limits (Reference 16).  The method detection limits are
      sample dependent and may vary as the sample matrix varies. Detection limits
      for solids can be estimated by dividing these values by the grams extracted per
      liter, which depends upon the extraction procedure. Divide solution detection
      limits by 10 for 1 g extracted to 100 ml for solid detection limits.

      Suggested concentration for instrument calibration (Reference 2).  Other
      calibration limits in the linear ranges may be used.

      dCalculated from 2-sigma data (Reference 5).

      "Highly dependent on operating conditions and plasma position.
52                                     Draft                               January 2001

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                                                                 Method 200.7
             TABLE 2: ON-LINE METHOD INTER-ELEMENT SPECTRAL
         INTERFERENCES ARISING FROM INTERFERANTS AT THE 100 mg/L
                                     LEVEL
Analyte
Ag
Al
As
B
Ba
Be
Ca
Cd
Ce
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Si02
Sn
Sr
Tl
Ti
V
Zn
Wavelength
(nm)
328.068
308.215
193.759
249.678
493.409
313.042
315.887
226.502
413.765
228.616
205.552
324.754
259.940
194.227
766.491
670.784
279.079
257.610
203.844
588.995
231.604
214.914
220.353
206.833
196.099
251.611
189.980
421.552
190.864
334.941
292.402
213.856
Interferant3
Ce, Ti, Mn
V, Mo, Ce, Mn
V, Al, Co, Fe, Ni
None
None
V, Ce
Co, Mo, Ce
Ni, Ti, Fe, Ce
None
Ti, Ba, Cd, Ni, Cr, Mo, Ce
Be, Mo, Ni
Mo, Ti
None
V, Mo
None
None
Ce
Ce
Ce
None
Co, TI
Cu, Mo
Co, Al, Ce, Cu, Ni, Ti, Fe
Cr, Mo, Sn, Ti, Ce, Fe
Fe
None
Mo, Ti, Fe, Mn, Si
None
Ti, Mo, Co, Ce, Al, V, Mn
None
Mo, Ti, Cr, Fe, Ce
Ni, Cu, Fe
       "These on-line interferences from method analytes and titanium only were
       observed using an instrument with 0.035 nm resolution (see Section 4.1.2).
       Interferant ranked by magnitude of intensity with the most severe interferant
       listed first in the row.
January 2001                           Draft                                  53

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Method 200.7
                     TABLE 3:  MIXED STANDARD SOLUTIONS
            Solution                           Analytes
              I                         Ag, As, B, Ba, Ca, Cd, Cu, Mn, Sb, and
              II                        Se
              III                        K, Li, Mo, Na, Sr, and Ti
              IV                        Co, P, V, and Ce
              V                        Al, Cr, Hg, Si02, Sn, and Zn
             	Be, Fe, Mg,  Ni, Pb, and TI	
54                                   Draft                            January 2001

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                                                                    Method 200.7
        TABLE 4:  TOTAL RECOVERABLE METHOD DETECTION LIMITS (MDL)a
                                               MDLs

            Analyte          Aqueous, mg/Lb            Solids, mg/kgc
Ag
Al
As
Bd
Ba
Be
Ca
Cd
Ce
Co
Cr
Cu
Fe
Hg
K
Li
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Si02
Sn
Sr
Tl
Ti
V
Y
Zn
0.002
0.02
0.008
0.003
0.001
0.0003
0.01
0.001
0.02
0.002
0.004
0.003
0.03e
0.007
0.3
0.001
0.02
0.001
0.004
0.03
0.005
0.06
0.01
0.008
0.02
0.02
0.007
0.0003
0.001
0.02
0.003

0.002
0.3
3
2

0.2
0.1
2
0.2
3
0.4
0.8
0.5
6
2
60
0.2
3
0.2
1
6
1
12
2
2
5

2
0.1
0.2
3
1

0.3
      a Table will be changed after interlaboratory validation of Method 200.7.
      bMDL concentrations are computed for original matrix with allowance for 2x
      sample preconcentration during preparation. Samples were processed in PTFE
      and diluted in 50-mL plastic centrifuge tubes.
      c Estimated, calculated from aqueous MDL determinations.
      d Boron not reported because of glassware contamination. Silica not
      determined in solid samples.
      e Elevated value due to fume-hood contamination.

January 2001                             Draft                                   55

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Method 200.7
TABLE 5: PERFORMANCE CRITERIA FOR METHOD 200.7 (TO BE DETERMINED
DURING INTERLABORATORY VALIDATION)
56                               Draft                          January 2001

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                                                Method 200.7
     Pb-Cu ICP-AES EMISSION PROFILE
32
30
28
26
24
22
20 -
18
16 -
14 -
   Net Emision Intensity Counts (X10 )
12
 475    525    575   625    675    725    775
          Nebulizer Argon Flow Rate - mL/min
                      Figure 1
                   825
  January 2001
Draft
57

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                                                                    Method 200.7
        Appendix A: Total Solids in Solid and Semisolid Matrices
1.0   Scope and Application

1.1   This procedure is applicable to the determination of total solids in such solid and
      semisolid samples as soils, sediments, biosolids (municipal sewage sludge)
      separated from water and wastewater treatment processes, and sludge cakes
      from vacuum filtration, centrifugation, or other biosolids dewatering processes.

1.2   This procedure is taken from EPA Method 1684: Total, Fixed, and Volatile Solids
      in Solid and Semi-Solid Matrices.

1.3   Method detection limits (MDLs) and minimum  levels (MLs) have not been
      formally established for this draft procedure.  These values will be determined
      during the validation  of Method 1684.

1.4   This procedure is performance based.  The laboratory is permitted to omit any
      step or modify any procedure (e.g. to overcome interferences, to lower the cost
      of measurement), provided that all performance requirements in this procedure
      are met.  Requirements for establishing equivalency are given in Section 9.1.2 of
      Method 200.7.

1.5   Each laboratory that  uses this procedure must demonstrate the ability to
      generate  acceptable results using the procedure in Section 9.2.

2.0   Summary of Method

2.1   Sample aliquots of 25-50 g are dried at 103C to 105C to drive off water in the
      sample.

2.3   The mass of total solids  in  the sample is determined by comparing the mass of
      the sample before and after each drying step.

3.0   Definitions

3.1   Total Solids-The residue left in the vessel after evaporation of liquid from a
      sample and subsequent drying in an oven at 103C to 105C.

3.2   Additional definitions are given in Sections 3.0 of Method 200.7.

4.0   Interferences

4.1   Sampling, subsampling,  and pipeting multi-phase samples may introduce
      serious errors (Reference 13.1).  Make and keep such samples homogeneous

January 2001                             Draft                                  ~

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Method 200.7
      during transfer.  Use special handling to ensure sample integrity when
      subsampling.  Mix small samples with a magnetic stirrer. If visible suspended
      solids are present, pipet with wide-bore pipets. If part of a sample adheres to
      the sample container, intensive homogenization is required to ensure accurate
      results. When dried, some samples form  a crust that prevents evaporation;
      special handling such as extended drying times are required to deal with this.
      Avoid using a  magnetic stirrer with samples containing magnetic particles.

4.2   The temperature and time of residue drying has an important bearing on results
      (Reference 1). Problems such as weight  losses due to volatilization of organic
      matter, and evolution of gases from heat-induced chemical decomposition,
      weight gains due to oxidation, and confounding factors like mechanical occlusion
      of water and water of crystallization depend on temperature and time of heating.
      It is therefore essential that samples be dried at a uniform temperature, and for
      no longer than specified. Each sample requires close attention to desiccation
      after drying. Minimize the time the desiccator is open because moist air may
      enter and be absorbed by the samples. Some samples may be stronger
      desiccants than those used in the desiccator and may take on water.

4.3   Residues dried at 103C to 105C may retain some bound water as water of
      crystallization  or as water occluded in the interstices of crystals. They lose C02
      in the conversion of bicarbonate to carbonate. The residues usually lose only
      slight amounts of organic matter by volatilization at this temperature. Because
      removal of occluded water is marginal at this temperature, attainment of constant
      weight may be very slow.

4.4   Results for residues high in oil or grease may  be questionable because of the
      difficulty of drying to constant weight in a reasonable time.

4.5   The determination of total solids is subject to negative error due to loss of
      ammonium carbonate and volatile organic matter during the drying step at
      103C to  105C. Carefully observe specified  ignition time and temperature to
      control losses of volatile inorganic salts if  these are a problem.

5.0   Safety

5.1   Refer to Section 5.0 of Method 200.7 for safety precautions.

6.0   Equipment  and Supplies

      NOTE: Brand names, suppliers, and part numbers are cited for illustrative purposes only. No
      endorsement is implied.  Equivalent performance may be achieved using equipment and
      materials other than those specified here, but demonstration of equivalent performance that
	meets the requirements of this method is the responsibility of the laboratory.	
                                       Draft                               January2001

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                                                                      Method 200.7
6.1   Evaporating Dishes-Dishes of 100-mL capacity. The dishes may be made of
      porcelain (90-mm diameter), platinum, or high-silica glass.

6.2    Watch glass-Capable of covering the evaporating dishes (Section 6.1).

6.3   Steam bath.

6.4   Desiccator-Moisture concentration in the desiccator should be monitored by an
      instrumental indicator or with a color-indicator desiccant.

6.5   Drying oven-Thermostatically-controlled, capable of maintaining a uniform
      temperature of 103C to 105C throughout the drying chamber.

6.6   Analytical balance-Capable of weighing to 0.1 mg for samples having a mass up
      to 200 g.

6.7   Container handling apparatus-Gloves, tongs, or a suitable holder for moving
      and handling hot containers after drying.

6.8   Bottles-Glass or plastic bottles of a suitable size for sample collection.

6.9   Rubber gloves (Optional).

6.10  No. 7 Cork borer (Optional).

7.0   Reagents and Standards

7.1   Reagent water-Deionized, distilled, or otherwise purified water.

7.2   Sodium chloride-potassium hydrogen phthalate standard (NaCI-KHP).

      7.2.1  Dissolve 0.10 g sodium chloride (NaCI) in 500 ml reagent water. Mix to
            dissolve.

      7.2.2  Add  0.10 g potassium hydrogen phthalate (KHP) to the NaCI solution
            (Section 7.2.1) and mix.  If the KHP does not dissolve readily, warm the
            solution while mixing. Dilute to 1 L with reagent water.  Store at 4C.
            Assuming 100% volatility of the acid phthalate  ion, this solution contains
            200  mg/L total solids, 81.0 mg/L volatile solids, and 119 mg/L fixed solids.


8.0   Sample Collection, Preservation, and Storage

8.1   Use resistant-glass  or plastic bottles to collect sample for solids analysis,
      provided that the material in suspension does not adhere to container walls.
      Sampling should be done in accordance with Reference 13.2. Begin analysis as
      soon as possible after collection because of the impracticality of preserving the
January 2001                              Draft                                    ~

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Method 200.7
      sample.  Refrigerate the sample at 4C up to the time of analysis to minimize
      microbiological decomposition of solids. Preferably do not hold samples more
      than 24 hours. Under no circumstances should the sample be held more than
      seven days. Bring samples to room temperature before analysis.

9.0   Quality Control

9.1   Quality control requirements and requirements for performance-based methods
      are given in Section 9.1 of Method 200.7.

9.2   Initial demonstration of  laboratory capability - The  initial demonstration of
      laboratory capability is used to characterize laboratory performance and method
      detection limits.

      9.2.1  Method detection limit (MDL) - The method  detection limit should be
            established for the analyte, using diluted NaCI-KHP standard (Section
            7.2). To determine MDL values, take seven replicate aliquots of the
            diluted NaCI-KHP solution and process each aliquot through each step of
            the analytical method. Perform all calculations and report the
            concentration values in the appropriate units. MDLs should be determined
            every year or whenever a modification to the method or analytical system
            is made that will  affect the method detection limit.

      9.2.2 Initial Precision and Recovery (IPR) - To establish the ability to generate
            acceptable precision and accuracy,  the analyst shall perform the following
            operations:

            9.2.2.1      Prepare four samples by diluting NaCI-KHP standard
                        (Section 7.2) to 1-5 times the MDL. Using the procedures in
                        Section 11, analyze these samples for total solids.

            9.2.2.2      Using the results of the four analyses, compute the average
                        percent recovery (x) and the standard deviation (s, Equation
                        1) of the percent recovery for total solids.

                                  Equation 1
                             .=
                                        n- l
            Where:
                  n = number of samples
                  x = % recovery in each sample
                  s = standard deviation
A-4                                    Draft                              January 2001

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                                                                      Method 200.7
            9.2.2.3      Compare s and x with the corresponding limits for initial
                        precision and recovery in Table 2 (to be determined in
                        validation study).  If s and x meet the acceptance criteria,
                        system performance is acceptable and analysis of samples
                        may begin.  If, however, s exceeds the precision limit or x
                        falls outside the range for recovery, system performance is
                        unacceptable. In this event, correct the problem, and repeat
                        the test.

9.3   Laboratory blanks

      9.3.1  Prepare and analyze a laboratory blank initially (i.e. with the tests in
            Section 9.2) and with each analytical batch.  The blank must be subjected
            to the same procedural steps as a sample, and will consist of
            approximately 25 g of  reagent water.

      9.3.2  If material is detected  in the blank at a concentration greater than the
            MDL (Section 1.3), analysis of samples must be halted until the source of
            contamination is eliminated and a new blank shows no evidence of
            contamination. All samples must be associated with an uncontaminated
            laboratory blank before the results may be reported for regulatory compli-
            ance purposes.

9.4   Ongoing Precision and  Recovery

      9.4.1  Prepare an ongoing precision and recovery (OPR) solution identical to
            the IPR solution described in Section 9.2.2.1.

      9.4.2  An aliquot of the OPR  solution must be analyzed with each sample batch
            (samples started through  the sample preparation process (Section 11) on
            the same 12-hour shift, to a maximum of 20 samples).

      9.4.3  Compute the percent recovery of total solids in the OPR sample.

      9.4.4  Compare the results to the limits for ongoing recovery in Table 2 (to be
            determined in validation study). If the results meet the acceptance criteria,
            system performance is acceptable and analysis of blanks and samples
            may proceed. If,  however, the recovery of total solids falls outside of the
            range given, the analytical processes are not being performed properly.
            Correct the problem, reprepare the sample batch, and repeat the OPR
            test. All samples must  be  associated with an OPR analysis that passes
            acceptance criteria before the sample results can be reported for
            regulatory compliance purposes.

      9.4.5  results that pass the specifications in Section 9.4.4 to IPR and previous
            OPR data.  Update QC charts to form a graphic representation of
            continued laboratory performance. Develop a statement of laboratory

January 2001                              Draft                                   ~

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Method 200.7
            accuracy for each analyte by calculating the average percent recovery (R)
            and the standard deviation of percent recovery (SR). Express the
            accuracy as a recovery interval from R-2SR to R+2SR. For example, if
            R=05% and SR=5%, the accuracy is 85-115%.

9.5   Duplicate analyses

      9.5.1  Ten percent of samples must be analyzed in duplicate. The duplicate
            analyses must be performed within the same sample batch (samples
            whose analysis is started within the same 12-hour period, to a maximum
            of 20 samples).

      9.5.2  The total solids of the duplicate samples must be within 10%.

10.0  Calibration and Standardization

10.1  Calibrate the analytical balance at 2 mg and 1000 mg using class "S" weights.

10.2  Calibration shall be within  10% (i.e. 0.2 mg) at 2 mg and  0.5% (i.e. 5 mg)
      at 1000 mg.  If values are not within these limits, recalibrate the balance.

11.0  Procedure

11.1  Preparation of evaporating dishes-Heat dishes and watch glasses at 103C to
      105C for 1 hour in an oven.  Cool and store the dried equipment in a
      desiccator. Weigh each dish and watch glass prior to use (record combined
      weight as "Wdish").

11.2  Preparation of samples

      11.2.1 Fluid samples-lf the sample contains enough moisture to flow readily, stir
            to homogenize, place a 25 to 50 g sample aliquot on the prepared
            evaporating dish.  If the sample is to be analyzed in duplicate, the mass of
            the two aliquots may not differ by more than 10%.  Spread each sample
            so that it is evenly distributed over the evaporating dish. Evaporate  the
            samples to dryness on a steam bath.  Cover each sample with a watch
            glass, and weigh (record weight  as "Wsampte").

      NOTE:  Weigh wet samples quickly because wet samples tend to lose weight by evaporation.
	Samples should be weighed immediately after aliquots are prepared.	


      11.2.2 Solid samples-lf the sample consists of discrete pieces of solid material
            (dewatered sludge, for example), take cores from each piece with a No. 7
            cork borer or pulverize the entire sample coarsely on a clean surface by
            hand, using rubber gloves. Place a 25 to 50 g sample aliquot of the
            pulverized sample on the prepared evaporating dish.  If the sample  is to

&-6                                    Draft                              January 2001

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                                                                       Method 200.7
             be analyzed in duplicate, the mass of the two aliquots may not differ by
             more than 10%. Spread each sample so that it is evenly distributed over
             the evaporating dish. Cover each sample with a watch glass, and weigh
             (record weight as "Wsample").

11.3  Dry the samples at 103C to 105C for a minimum of 12 hours, cool to balance
      temperature in an individual desiccator containing fresh desiccant, and weigh.
      Heat the residue again for 1 hour, cool it to balance temperature in a desiccator,
      and weigh. Repeat this heating, cooling, desiccating,  and weighing procedure
      until the weight change is less than 5% or 50 mg, whichever is less. Record the
      final weight as "Wtotal."

      NOTE: It is imperative that dried samples weighed quickly since residues often are very
      hygroscopic and rapidly absorb moisture from the air. Samples must remain in the dessicator
	until the analyst is ready to weigh them.	


12.0 Data Analysis and Calculations

12.1  Calculate the % solids or the mg solids/kg sludge for total solids (Equation 2).

                                   Equation 2
                         % total solids = ^	 * 100
                                     "sample ~ "dish
                         or
                         mg total solids   W. ., - W,.,
                         	= ^	^-* 1 000 000
                           kg sludge    Wsample - Wdish

                   Where:
                         Wdjsh=Weight of dish (mg)
                         Wsample=Weight of wet sample and dish (mg)
	W^fal=Weight of dried residue and dish (mg)	

12.2  Sample results should be reported as % solids or mg/kg to three significant
      figures. Report results below the ML as < the ML, or as required by the
      permitting authority or in the permit.

13.0 Method Performance

13.1  Method performance (MDL and quality control acceptance criteria) will be
      determined during the multi-lab validation of this method.

13.2  Total solids duplicate  determinations must agree within 10% to be reported for
      permitting purposes.  If duplicate samples do not meet this criteria, the problem
      must be discovered and the sample must be run over.

January 2001                              Draft                                    ~

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Method 200.7
14.0  Pollution Prevention

14.2  Pollution prevention details are given in Section 14 of Method 200.7.

15.0  Waste Management

15.1  Waste management details are given in Section 15 of Method 200.7.

16.0  References

16.1  "Standard Methods for the Examination of Water and Wastewater," 18th ed. and
      later revisions, American Public Health Association, 1015 15th Street NW,
      Washington, DC 20005.  1-35: Section 1090 (Safety), 1992.

16.2  U.S. Environmental Protection Agency, 1992. Control of Pathogens and Vector
      Attraction in Sewage Sludge. Publ 625/R-92/013. Office of Research and
      Development, Washington, DC.

17.0  Tables, Diagrams,  Flowcharts, and Validation Data

17.1  Tables containing method requirements for QA/QC will be added after the
      validation study has been performed.
                                    Draft                            January 2001

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