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           METHOD 524.1.  MEASUREMENT OF  PUR6EABLE ORGANIC  COMPOUNDS
         IN WATER BY PACKED COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY
                                  Revision 3.0
.A.  AT ford-Stevens,  J.  W.  Eichelberger,  W.  L.  Budde - Method 524,  Revision 1.0
 (1983)

 J.  E. Longbottom,  R. W.  Slater,  Jr.  - Method  524.1, Revision 2.0  (1986)

 J.  W. Eichelberger, W.  L.  Budde  - Method 524.1,  Revision 3.0 (1989)
                  ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
                      OFFICE OF RESEARCH AND DEVELOPMENT
                     U.S. ENVIRONMENTAL PROTECTION AGENCY
                            CINCINNATI, OHIO  45268
                                      253

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                                 METHOD 524.1
            MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY
              PACKED COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY
1.   SCOPE AND APPLICATION

     1.1  This is a general purpose method for the identification and simul-
          taneous measurement of purgeable volatile organic compounds in
          finished drinking water, raw source water, or drinking water in any
          treatment stage (1).  The method is applicable to a wide range of
          organic compounds, including the four trihalomethane disinfection
          by-products, that have sufficiently high volatility and low water
          solubility to be efficiently removed from water samples with purge
          and trap procedures.  The following compounds are method analytes,
          and single-laboratory accuracy, precision, and method detection
          limit data have been determined with this method for 31 of them3.
              Compound

          Benzene
          Bromobenzene
        * Bromochloromethane
          Bromodi chloromethane
          Bromoform
        * Bromomethane
          Carbon tetrachloride
          Chlorobenzene
        * Chloroethane
          Chloroform
        * Chloromethane
        * 2-Chlorotoluene
        * 4-Chlorotoluene
          Di bromochloromethane
          1,2-Di bromo-3-chloropropane
          1,2-Dibromoethane
          Dibromomethane
          1,2-DiChlorobenzene
        * 1,3-Dichlorobenzene
          1,4-Di chlorobenzene
          Di chlorodi f1uoromethane
          1,1-Dichloroethane
          1,2-Dichloroethane
          1,1-Dichloroethene
        * cis-1,2-Dichloroethene
          trans-1,2-Di chloroethene
          1,2-Dichloropropane
          1,3-Di chloropropane
Chemical Abstract Service
	Registry Number

           71-43-2
          108-86-1
           74-97-5
           75-27-4
           75-25-2
           74-83-9
           56-23-5
          108-90-7
           75-00-3
           67-66-3
           74-87-3
           95-49-8
          106-43-4
          124-48-1
           96-12-8
          106-93-4
           74-95-3
           95-50-1
          541-73-1
          106-46-7
           75-71-8
           75-34-3
          107-06-2
           75-35-4
          156-59-4
          156-60-5
           78-87-5
          142-28-9

                                      254

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   * 2,2-Dichloropropane                            590-20-7
   * 1,1-Dichloropropene                            563-58-6
   * cis-l,3-Dichloropropene                      10061-01-5
   * trans-l,3-Dichloropropene                    10061-02-6
   * Ethyl benzene                                   100-41-4
     Methylene chloride                              75-09-2
     Styrene                                        100-42-5
   * 1,1,1,2-Tetrachloroethane                      630-20-6
     1,1,2,2-Tetrachloroethane                       79-34-5
     Tetrachloroethene                              127-18-4
     Toluene                                        108-88-3
     1,1,1-Trichloroethane                           71-55-6
   * 1,1,2-Trichloroethane                           79-00-5
     Trichloroethene                                 79-01-6
     Trichlorofluoromethane                          75-69-4
   * 1,2,3-Trichloropropane                          96-18-4
     Vinyl chloride                                  75-01-4
     o-Xylene                                        95-47-6
   * m-Xylene                                       108-38-3
     p-Xylene                                       106-42-3


   a Compounds preceded by an asterisk are known to be amenable to purge
     and trap extraction (see Method 524.2), and chromatography on the
     packed gas chromatography column used in this method, but precision,
     accuracy, retention time, and method detection limit data is not
     provided in this method.

.1.2  Method detection limits (MDLs) (2) are compound and instrument
     dependent and vary from approximately 0.1-2 /jg/L.  The applicable
     concentration range of this method is also compound and instrument
     dependent and is approximately 0.1 to 200 M9/L-  Analytes that are
     inefficiently purged from water will not be detected when present at
     low concentrations, but they can be measured with acceptable
     accuracy and precision when present in sufficient amounts.

1.3  Analytes that are not separated chromatographically, but which have
     different mass spectra and non-interfering quantitation ions, can be
     identified and measured in the same calibration mixture or water
     sample (Sect. 11.9.2).  Table 1 lists primary and secondary
     quantitation ions for each analyte.  Analytes which have very
     similar mass spectra cannot be individually identified and measured
     in the same calibration mixture or water sample unless they have
     different retention times (Sect.11.9.3).  Coeluting compounds with
     very similar mass spectra, typically many structural isomers, must
     be reported as an isomeric group or pair.  Cis- and trans-
     1,2-dichloroethene, two of the three isomeric xylenes, and two of
     the three dichlorobenzenes are three examples of structural  isomers
     that cannot be explicitly identified if more than one member of the
     isomeric group is present. These groups of isomers must be reported
     as isomeric pairs (see Method 524.2 for an alternative approach).


                                 255

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2.   SUMMARY OF METHOD

     2.1  Volatile organic compounds and surrogates with low water solubility
          are extracted (purged) from the sample matrix by bubbling an inert
          gas through the aqueous sample.  Purged sample components are
          trapped in a tube containing suitable sorbent materials.  When
          purging is complete, the sorbent tube is heated and backflushed with
          helium to desorb the trapped sample components into a packed gas
          chromatography (GC) column interfaced to a mass spectrometer (MS).
          The column is temperature programmed to separate the method analytes
          which are then detected with the MS.  Compounds eluting from the GC
          column are identified by comparing their measured mass spectra and
          retention times to reference spectra and retention times in a data
          base.  Reference spectra and retention times for analytes are
          obtained by the measurement of calibration standards under the same
          conditions used for samples.  The concentration of each identified
          component is measured by relating the MS response of the
          quantisation ion produced by that compound to the MS response of the
          quantitation ion produced by a compound that is used as an internal
          standard.  Surrogate analytes, whose concentrations are known in
          every sample, are measured with the same internal standard
          calibration procedure.

3.   DEFINITIONS

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

     3.2  Surrogate analyte — A pure analyte(s), which is extremely unlikely
          to be found in any sample, and which is added to a sample aliquot in
          known amount(s) before extraction and is measured with the same
          procedures used to measure other sample components.  The purpose of
          a surrogate analyte is to monitor method performance with each
          sample.

     3.3  Laboratory duplicates (LD1 and LD2) -- Two sample aliquots taken in
          the analytical laboratory and analyzed separately with identical
          procedures.  Analyses of LD1 and LD2 give a measure of the precision
          associated with laboratory procedures, but not with sample
          collection, preservation, or storage procedures.

     3.4  Field duplicates (FD1 and FD2) — Two separate samples collected at
          the same time and place under identical circumstances and treated
          exactly the same throughout field and laboratory procedures.
          Analyses of FD1 and FD2 give a measure of the precision associated
          with sample collection, preservation and storage, as well as with
          laboratory procedures.
                                      256

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

3.6   Field reagent blank (FRB) — Reagent water placed in a sample
      container in the laboratory and treated as a sample in all respects,
      including exposure  to sampling site conditions, storage,
      preservation and all analytical procedures. The purpose of the FRB
      is to determine if  method analytes or other interferences are
      present in the field environment.

3.7   Laboratory performance check solution (LPC) ~ A solution of one or
      more compounds used to evaluate the performance of the instrument
      system with respect to a defined set of method criteria.

3.8   Laboratory fortified blank (LFB) — An aliquot of reagent water to
      which known quantities of the method analytes are added in the
      laboratory.  The LFB is analyzed exactly like a sample, and its
      purpose is to determine whether the methodology is in control, and
      whether the laboratory is capable of making accurate and precise
      measurements at the required method detection limit.

3.9   Laboratory fortified sample matrix (LFM) — An aliquot of an
      environmental sample to which known quantities of the method
      analytes are added  in the laboratory.  The LFM is analyzed exactly
      like a sample, and  its purpose is to determine whether the sample
      matrix contributes bias to the analytical  results.  The background
      concentrations of the analytes in the sample matrix must be
      determined in a separate aliquot and the measured values in the LFM
      corrected for background concentrations.

3.10  Stock standard solution — A concentrated solution containing a
      single certified standard that is a method analyte,  or a
      concentrated solution of a single analyte prepared in the laboratory
     with an assayed reference compound.   Stock standard solutions are
      used to prepare primary dilution standards.

3.11  Primary dilution standard solution — A solution of several  analytes
     prepared in the laboratory from stock standard solutions and diluted
     as needed to prepare calibration solutions and other  needed analyte
     solutions.

3.12 Calibration standard (CAL) — A solution prepared from the primary
     dilution standard solution and stock standard solutions of the
      internal  standards and surrogate analytes.   The CAL solutions are
     used to calibrate the instrument response  with respect to analyte
     concentration.
                                257

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3.13 Quality control sample (QCS) — A sample matrix containing method.
     analytes or a solution of method analytes in a water miscible
     solvent which is used to fortify reagent water or environmental
     samples.  The QCS is obtained from a source external to the
     laboratory, and is used to check laboratory performance with
     externally prepared test materials.

INTERFERENCES

4.1  During analysis, major contaminant sources are volatile materials
     in the laboratory and impurities in the inert purging gas and in the
     sorbent trap.  The use of non-polytetrafluoroethylene (PTFE) plastic
     tubing, non-PTFE thread sealants, or flow controllers with rubber
     components in the purging device should be avoided since such
     materials out-gas organic compounds which will be concentrated in
     the trap during the purge operation.  Analyses of laboratory reagent
     blanks provide information about the presence of contaminants.  When
     potential interfering peaks are noted in laboratory reagent blanks,
     the analyst should change the purge gas source and regenerate the
     molecular sieve purge gas filter.  Subtracting blank values from
     sample results is not permitted.

4.2  Interfering contamination may occur when a sample containing low
     concentrations of volatile organic compounds is analyzed immediately
     after a sample containing relatively high concentrations of volatile
     organic compounds.  A preventive technique is between-sample rinsing
     of the purging apparatus and sample syringes with two portions of
     reagent water.  After analysis of a sample containing high
     concentrations of volatile organic compounds, one or more laboratory
     reagent blanks should be analyzed to check for cross contamination.

4.3  Special precautions must be taken to determine methylene chloride.
     The analytical and sample storage area should be isolated from all
     atmospheric sources of methylene chloride, otherwise random
     background levels will result.  Since methylene chloride will
     permeate through PTFE tubing, all gas chromatography carrier gas
     lines and purge gas plumbing should be constructed of stainless
     steel or copper tubing.  Laboratory worker's clothing should be
     cleaned frequently since clothing previously exposed to methylene
     chloride fumes during common liquid/liquid extraction procedures can
     contribute to  sample contamination.

SAFETY

5.1  The toxicity or carcinogen!city of chemicals used in this method
     has not been precisely defined; each chemical should be treated as  a
     potential health hazard, and exposure to these chemicals should be
     minimized.  Each laboratory is responsible for maintaining  awareness
     of OSHA regulations regarding safe handling of chemicals used in
     this method.   Additional references to laboratory safety are
     available  (3-5) for the information of the analyst.
                                 258

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5.2  The following method analytes have been tentatively classified as
     known or suspected human or mammalian carcinogens:  benzene, carbon
     tetrachloride, 1,4-dichlorobenzene, 1,2-dichlorethane,
     1,1,2,2-tetrachloroethane, 1,1,2-trichloroethane, chloroform,
     1,2-dibromoethane, tetrachloroethene, trichloroethene, and vinyl
     chloride.  Pure standard materials and stock standard solutions of
     these compounds should be handled in a hood.  A NIOSH/MESA approved
     toxic gas respirator should be worn when the analyst handles high
     concentrations of these toxic compounds.

APPARATUS AND EQUIPMENT

6.1  SAMPLE CONTAINERS — 60-mL to 120-mL screw cap vials (Pierce #19832
     or equivalent) each equipped with a PTFE-faced silicone septum
     (Pierce #12718 or equivalent).  Prior to use, wash vials and septa
     with detergent and rinse with tap and distilled water.  Allow the
     vials and septa to air dry at room temperature, place in a 105°C
     oven for 1 hr, then remove and allow to cool in an area known to be
     free of organics.

6.2  PURGE AND TRAP SYSTEM — The purge and trap system consists of three
     separate pieces of equipment:  purging device,  trap, and desorber.
     Systems are commercially available from several sources that meet
     all of the following specifications.

     6.2.1  The all glass purging device (Figure 1)  should be designed to
            accept 25-mL samples with a water column at least 5 cm deep.
            A smaller (5-mL) purging device is recommended if the GC/MS
            system has adequate sensitivity to obtain the method
            detection limits required.   Gaseous volumes above the sample
            must be kept to a minimum (<15 ml) to eliminate dead volume
            effects.   A glass frit should  be installed at the base of the
            sample chamber so the purge gas passes through the water
            column as finely divided bubbles with a  diameter of <3 mm at
            the origin.   Needle spargers may be used,  however,  the purge
            gas must  be introduced at a point about  5 mm from the base of
            the water column.

     6.2.2  The trap  (Figure 2)  must be at least 25  cm long and have an
            inside diameter of at least 0.105 in.  Starting from the
            inlet, the trap should contain 1.0 cm of methyl  silicone
            coated packing and the following amounts of adsorbents:   1/3
            of 2,6-diphenylene oxide polymer,  1/3 of silica gel,  and 1/3
            of coconut charcoal.   If it is not necessary to determine
            dichlorodifluoromethane,  the charcoal  can  be eliminated  and
            the polymer increased to fill  2/3 of the trap.   Before
            initial use,  the trap should be conditioned overnight at
            180°C  by backflushing with  an  inert  gas  flow  of at  least
            20 mL/min.   Vent the  trap effluent to the  room,  not to the
            analytical  column.   Prior to daily use,  the trap  should  be
            conditioned  for 10 min  at 180°C with backflushing.  The trap
            may be vented  to the  analytical  column during daily

                                259

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            conditioning; however, the column must be run through the
            temperature program prior to analysis of samples.

     6.2.3  The use, of the methyl silicone coated packing is recommended,
            but not mandatory.  The packing serves a dual purpose of
            protecting the Tenax adsorbant from aerosols, and also of
            insuring that the Tenax is fully enclosed within the heated
            zone of the trap thus eliminating potential  cold spots.
            Alternatively, silanized glass wool may be used as a spacer
            at the trap inlet.

     6.2.4  The desorber (Figure 2) must be capable of rapidly heating
            the trap to « 180°C.   The polymer section of the trap should
            not be heated higher than 200°C or the life  expectancy of the
            trap will decrease.  Trap failure is characterized by a
            pressure drop in excess of 3 pounds per square inch across
            the trap during purging or by poor bromoform sensitivities.
            The desorber design illustrated in Figure 2  meets these
            criteria.

6.3  GAS CHROMATOGRAPHY/MASS SPECTROMETER/DATA SYSTEM (GC/MS/DS)

     6.3.1  The GC must be capable of temperature programming and should
            be equipped with variable-constant differential flow
            controllers so that the column flow rate will remain constant
            throughout desorption and temperature program operation.  The
            column oven may require cooling to <30 C; therefore, a
            subambient oven controller may be required.   The GC usually
            is interfaced to the MS with an all-glass enrichment device
            and an all-glass transfer line, but any enrichment device or
            transfer line can be used if the performance specifications
            described in this method can be achieved.

     6.3.2  Gas Chromatography Column — 1.5 to 2.5 m x 2 mm ID stainless
            steel or glass, packed with 1% SP-1000 on Carbopack-B (60/80
            mesh) or the equivalent.

     6.3.3  The mass spectrometer must be capable of electron ionization
            at a nominal electron energy of 70 eV.  The  spectrometer must
            be capable of scanning from 35 to 260 amu with a complete
            scan cycle time (including scan overhead) of 7 seconds or
            less.  (Scan cycle time = Total MS data acquisition time in
            seconds divided by number of scans in the chromatogram).  The
            spectrometer must produce a mass spectrum that meets all
            criteria in Table 2 when 50 ng or less of 4-bromof1uoro-
            benzene (BFB) is introduced into the GC.  An average spectrum
            across the BFB GC peak may be used to test instrument
            performance.

     6.3.4  An interfaced data system is required to acquire, store,
            reduce, and output mass spectral data.  The computer software
            should have the capability of processing stored GC/MS data by

                                 260

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                 recognizing  a  GC  peak within  any given retention  time window,
                 comparing  the  mass  spectra  from the GC peak with  spectral
                 data  in  a  user-created data base,  and generating  a  list of
                 tentatively  identified compounds with their retention times
                 and scan numbers.   The software must allow integration of the
                 ion abundance  of  any specific  ion  between specified time or
                 scan  number  limits.  The software  should also allow calcu-
                 lation of  response  factors  as  defined in Sect. 9.2.6 (or
                 construction of a second or third  order regression
                 calibration  curve), calculation of response factor  statistics
                 (mean and  standard  deviation), and calculation of concentra-
                 tions of analytes using either the calibration curve or the
                 equation in  Sect. 12.

     6.4  SYRINGE AND  SYRINGE VALVES

          6.4.1  Two 5-mL or  25-mL glass hypodermic syringes with  Luer-Lok tip
                 (depending on  sample volume used).

          6.4.2  Three 2-way  syringe valves with Luer ends.

          6.4.3  One 25-/iL micro syringe with a 2 in x 0.006 in ID,  22° bevel
                 needle (Hamilton #702N or equivalent).

          6.4.4  Micro syringes - 10, 100 /z.L.

          6.4.5  Syringes - 0.5, 1.0, and 5-mL, gas tight with shut-off valve.

     6,5  MISCELLANEOUS

          6.5.1  Standard solution storage containers - 15-mL bottles with
                 PTFE-lined screw caps.

7.  REAGENTS AND CONSUMABLE MATERIALS

     7.1  TRAP PACKING MATERIALS

          7.1.1  2,6-Diphenylene oxide polymer, 60/80 mesh,  chromatographic
                 grade (Tenax GC or equivalent).

          7.1.2  Methyl silicone packing (optional)  - OV-1  (3%)  on Chromosorb
                 W,  60/80 mesh,  or equivalent.

          7.1.3  Silica gel  — 35/60  mesh,  Davison,  grade  15  or  equivalent.

          7,1.4  Coconut charcoal  ~  Prepare  from Barnebey  Cheney,  CA-580-26
                 lot #M-2649 by crushing through 26  mesh  screen.

     7.2  COLUMN PACKING MATERIALS

          7.2.1  1%  SP-1000  on 60/80  mesh  Carbopack-B or equivalent.


                                     261

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7.3  REAGENTS

     7.3.1  Methanol — Demonstrated to be free of analytes.

     7.3.2  Reagent water -- Prepare reagent water by passing tap water
            through a filter bed contai-ning about 0.5 kg of activated
            carbon, by using a water purification system, or by boiling
            distilled water for 15 min followed by a 1-h purge with inert
            gas while the water temperature is held at 90 C.   Store in
            clean, narrow-mouth bottles with PTFE-lined septa and screw
            caps.

     7.3.3  Hydrochloric acid (1+1) — Carefully add measured volume of
            cone. HC1 to equal volume of reagent water.

     7.3.4  Vinyl chloride — Certified mixtures of vinyl chloride in
            nitrogen and 99.9% pure vinyl chloride are available from
            several sources (for example, Matheson, Ideal Gas Products,
            and Scott Gases).

     7.3.5  Ascorbic Acid — ACS reagent grade, granular.

7.4  STOCK STANDARD SOLUTIONS — These solutions may be purchased as
     certified solutions or prepared from pure standard materials using
     the following procedures.  One of these solutions is required for
     every analyte of concern, every surrogate, and the internal
     standard.  A useful working concentration is about 1-5 mg/mL.

     7.4.1  Place about 9.8 ml of methanol into a 10-mL ground-glass
            stoppered volumetric flask.  Allow the flask to stand,
            unstoppered, for about 10 min or until all alcohol-wetted
            surfaces have dried and weigh to the nearest 0.1 mg.

     7.4.2  If the analyte is a liquid at room temperature, use a 100-0L
            syringe and immediately add two or more drops of reference
            standard to the flask.  Be sure that the reference standard
            falls directly into the alcohol without contacting the neck
            of the flask.  If the analyte is a gas at room temperature,
            fill a 5-mL valved gas-tight syringe with the standard to the
            5.0-mL mark, lower the needle to 5 mm above the methanol
            meniscus, and slowly inject the standard into the neck area
            of the flask.  The gas will rapidly dissolve in the methanol.

     7.4.3  Reweigh, dilute to volume, stopper, then mix by inverting the
            flask several times.  Calculate the concentration in ng/n\-
            from the net gain in weight.  When compound purity is
            certified at 96% or greater, the weight can be used without
            correction to calculate the concentration of the stock
            standard.

     7.4.4  Store stock standard solutions in 15-mL bottles equipped
            with PTFE-lined screw caps.  Methanol solutions prepared from

                                 262

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            liquid analytes are stable for at least four weeks when
            stored at 4 C.  Methanol solutions prepared from gaseous
        ,    analytes are  not stable for more than one week when  stored at
            <0°C; at room temperature, they must be discarded after one
            day.

7.5  PRIMARY DILUTION STANDARDS — Use stock standard solutions  to
     prepare primary dilution standard solutions that contain all the
     analytes of concern  and the surrogates (but not the internal
     standard!) in methanol.  The primary dilution standards should be
     prepared at concentrations that can be easily diluted to prepare
     aqueous calibration  solutions that will bracket the working
     .concentration range.  Store the primary dilution standard solutions
     with minimal headspace and check frequently for signs of
     deterioration or evaporation, especially just before preparing
     calibration solutions.  Storage times described for stock standard
     solutions in Sect. 7.4.4 also apply to primary dilution standard
     solutions.

7.6  FORTIFICATION SOLUTIONS FOR INTERNAL STANDARD AND SURROGATES

     7.6.1  A solution containing the internal standard and surrogates is
            required to prepare laboratory reagent blanks (also used as a
            laboratory performance check solution), and to fortify each
            sample.  Prepare a fortification solution containing fluoro-
            benzene (internal standard), l,2-dichlorobenzene-d4
            (surrogate),  and BFB (surrogate) in methanol at concen-
            trations of 5 fig/ml of each.  A 10-0L aliquot of this
.  ,          solution added to a 25-mL water sample volume gives
            concentrations of 2 /zg/L of each.   A 10-juL aliquot of this
            solution added to a 5-mL water sample volume gives a
            concentration of 10 /jg/L of each.   Additional internal
            standards and surrogate analytes are optional.

     7.6.2 ,A solution of the internal standard alone is required to
            prepare calibration standards,  laboratory fortified blanks,
            etc. The internal standard should be in methanol  at a concen-
            tration of 5 /ig/mL.

7.7  PREPARATION OF LABORATORY REAGENT BLANK — Fill  a 25-mL (or 5-mL)
     syringe with reagent water and adjust to the mark (no air bubbles).
     Inject 10 pi of the fortification solution containing the internal
     standard and surrogates through the Luer Lok valve into the reagent
     water.  Transfer the LRB to the purging device.   See Sect.  11.1.2.

7:'8  PREPARATION OF LABORATORY FORTIFIED BLANK — Prepare this exactly
     like  a calibration standard.   See Sect.  7.9.

7.9  PREPARATION OF CALIBRATION STANDARDS

     7.9.1  The number of calibration  solutions (CALs)  needed depends on
            the calibration range  desired.   A minimum of three CAL

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                 solutions is required to calibrate a range of a factor of 20
                 in concentration.  For a factor of 50 use at least four
                 standards, and for a factor of 100 at least five standards.
                 One calibration standard should contain each analyte of
                 concern and each surrogate at .a concentration of 2-10 times
                 the method detection limit (Table 3) for that compound.  The
                 other CAL standards should contain each analyte of concern
                 and each surrogate at concentrations that define the range of
                 the method.  Every CAL solution contains the internal
                 standard at the same concentration (10 /zg/L suggested).

          7.9.2  To prepare a calibration standard, add an appropriate volume
                 of a primary dilution standard (containing analytes and
                 surrogates) to an aliquot of reagent water in a volumetric
                 flask.  Use a microsyringe and rapidly inject the methanol
                 solutions into the expanded area of the filled volumetric
                 flask.  Remove the needle as quickly as possible after
                 injection.  Mix by inverting the flask three times only.
                 Discard the contents contained in the neck of the flask.
                 Aqueous standards are not stable in a volumetric flask and
                 should be discarded after 1 hr. unless transferred to a
                 sample bottle and sealed immediately.

8.   SAMPLE COLLECTION. PRESERVATION. AND STORAGE

     8.1  SAMPLE COLLECTION, DECHLORINATION, AND PRESERVATION
          8.1.1
          8.1.2
          8.1.3
          8.1.4
Collect all samples in duplicate.  If samples contain
residual chlorine, and measurements of the concentrations of
disinfection by-products (trihalomethanes, etc.) at the time
of sample collection are desired, add about 25 mg of ascorbic
acid to the sample bottle before filling.  Fill sample
bottles to overflowing, but take care not to flush out the
rapidly dissolving ascorbic acid.  No air bubbles should pass
through the sample as the bottle is filled, or be trapped in
the sample when the bottle is sealed.  Adjust the pH of the
duplicate samples to <2 by carefully adding one drop of 1:1
HC1 for each 20 mL of sample volume.  Seal the sample
bottles, PFTE-face down, and shake vigorously for 1 min.

When sampling from a water tap, open the tap and allow the
system to flush until the water temperature has stabilized
(usually about 10 min).  Adjust the flow to about 500 mL/min
and collect duplicate samples from the flowing stream.

When sampling from an open body of water, fill a 1-quart
wide-mouth bottle or 1-liter beaker with sample from a
representative area, and carefully fill duplicate sample
bottles from the 1-quart container.

The samples must be chilled to 4°C on the day of collection
and maintained at that temperature until analysis.  Field

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                 samples that will  not be received at the laboratory on the
                 day of collection  must be packaged for shipment with
                 sufficient ice to  ensure that they will  be at 4°C on arrival
                 at the.laboratory.

     8.2  SAMPLE STORAGE

          8.2.1  Store samples at 4°C until  analysis.   The sample storage  area
                 must be free of organic solvent vapors.

          8.2.2  Analyze all samples within 14 days of collection.  Samples
                 not analyzed within this period must be discarded and
                 replaced.

     8.3  FIELD REAGENT BLANKS

          8.3.1  Duplicate field reagent blanks must be handled along with
                 each sample set, which is composed of the samples collected
                 from the same general sample site at approximately the same
                 time.  At the laboratory, fill field blank sample bottles
                 with reagent water, seal, and ship to the sampling site along
                 with empty sample  bottles and back to the laboratory with
                 filled sample bottles.  Wherever a set of samples is shipped
                 and stored, it is  accompanied by appropriate blanks.

          8.3.2  Use the same procedures used for samples to add ascorbic acid
                 and HC1 to blanks  (Sect. 8.1.1).

9.  CALIBRATION

     9.1  Demonstration and documentation of acceptable initial calibration is
          required before any samples are analyzed and is required intermit-
          tently throughout sample  analysis as dictated by results of
          continuing calibration checks.  After initial calibration is
          successful, a continuing  calibration check is required at the
          beginning of each 8 hr period during which analyses are performed.
          Additional periodic calibration checks are good laboratory practice.

     9.2  INITIAL CALIBRATION

          9.2.1  Calibrate the mass and abundance scales of the MS with
                 calibration compounds and procedures prescribed by the
                 manufacturer with  any modifications necessary to meet the
                 requirements in Sect. 9.2.2.

          9.2.2  Introduce into the GC (either by purging a laboratory reagent
                 blank or making a syringe injection) 50 ng of BFB and acquire
                 mass spectra for m/z 35-260 at 70 eV (nominal).  Use the
                 purging procedure  and/or GC conditions given in Sect. 11.  If
                 the spectrum does  not meet all criteria in Table 2, the MS
                 must be retuned and adjusted to meet all criteria before
                 proceeding with calibration.  An average spectrum across the

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9.2.3
9.2.4
9.2.5
9.2.6
GC peak may be used to evaluate the performance of the
system.

Purge a medium CAL solution, for example 10-20 M9/L, using
the procedure given in Sect. 11.
Performance criteria for the medium calibration.
stored GC/MS data with the data system software.
shows an acceptable total ion chromatogram.
Examine the
Figure 3
9.2.4.1 GC performance. Good column performance will produce
        symmetrical peaks with minimum tailing for most
        compounds.  If peaks are broad, or sensitivity poor,
        replace or repack the column.  During handling,
        packing, and programming, active sites can be exposed
        on the Carbopack-B packing which can result in
        tailing peak geometry and poor resolution of many
        constituents.  Pneumatic shocks and rough treatment
        of packed columns will cause excessive fracturing of
        the packing.  If pressure in excess of 60 psi is
        required to obtain 40 mL/min carrier flow, the column
        should be repacked.  With the column connected to the
        MS interface, a pressure below about 10"5  mm of Hg
        indicates the jet separator is clogged.

9.2.4.2 MS sensitivity. The GC/MS peak identification
        software should be able to recognize a GC peak in the
        appropriate retention time window for each of the
        compounds in calibration solution, and make correct
        tentative identifications.  If fewer than 99% of the
        compounds are recognized, system maintenance is
        required.  See Sect. 9.3.6.

If all performance criteria are met, purge an aliquot of each
of the other CAL solutions using the same GC/MS conditions.

Calculate a response factor (RF) for each analyte, surrogate,
and isomer pair, for each CAL solution using the internal
standard fluorobenzene.  Table 1 contains suggested quantita-
tion ions for all compounds.  This calculation is supported
in acceptable GC/MS data system software (Sect. 6.3.4), and
many other software programs.  RF is a unit!ess number, but
units used to express quantities of analyte and internal
standard must be equivalent.
               RF
                     (Ais)(Qx)
       where:  Ax  = integrated abundance  of the quantitation  ion
                     of the analyte.

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                    Ais = Integrated abundance of the quantitation  ion
                          of the internal  standard.
                    Qx = quantity  of  analyte  purged  in  ng  or
                          concentration units.
                    Qis = quantity  of  internal standard  purged  in ng
                          or concentration units.

            9.2.6.1 For each analyte and surrogate, calculate the mean RF
                    from the analyses  of the CAL solutions.  Calculate
                    the standard deviation (SD)  and the relative standard
                    deviation (RSD) from each mean: ,RSD = 100 (SD/M).
                    If the RSD of any  analyte or surrogate mean RF
                    exceeds  20%, either analyze additional aliquots of
                    appro-priate CAL solutions to obtain an acceptable
                    RSD of RFs over the entire concentration range, or
                    take action to improve GC/MS performance.  See Sect.
                    9.2.7.

     9,2.7  As an alternative to calculating mean response factors and
            applying the RSD test,  use the GC/MS data system software or
            other available software to generate a second or third order
            regression calibration curve.

9.3  Continuing calibration check.   Verify the MS tune and initial
     calibration at the beginning of each 8 hr work shift during which
     analyses are performed using the  following procedure.

     9.3.1  Introduce into the GC  (either by purging a laboratory reagent
            blank or making a syringe  injection) 50 ng of BFB and acquire
            a mass spectrum that includes data for m/z 35-260.  If the
            spectrum does not meet all criteria (Table 2),  the MS must be
            retuned and adjusted to meet all criteria before proceeding
            with the continuing calibration check.

     9.3.2  Purge a medium concentration CAL solution and analyze with
            the same conditions used during the initial  calibration.

     9.3.3  Demonstrate acceptable performance for the criteria shown in
            Sect. 9.2.4.

     9.3.4  Determine that the absolute areas of the quantitation ions of
            the internal  standard and  surrogates have not decreased by
            more than 30% from the areas measured in the most recent
            continuing calibration check,  or by more than 50% from the
            areas measured during  initial  calibration.  If these areas
            have decreased by more than these amounts, adjustments must
            be made to restore system sensitivity.  These adjustments may
            require cleaning of the MS ion source, or other maintenance
            as indicated in Sect. 9.3.6, and recalioration.  Control
            charts are useful aids in  documenting system sensitivity
            changes.


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     9.3.5  Calculate the RF for each analyte and surrogate from the data
            measured in the continuing calibration check.  The RF for
            each analyte and surrogate must be within 30% of the mean
            value measured in the initial calibration.  Alternatively, if
            a second or third order regression is used, the point from
            the continuing calibration check for each analyte and
            surrogate must fall, within the analyst's judgment, on the
            curve from the initial calibration.  If these conditions do
            not exist, remedial action must be taken which may require
            reinitial calibration.

     9.3.6  Some possible remedial actions.  Major maintenance such as
            cleaning an ion source, cleaning quadrupole rods, etc.
            require returning to the initial calibration step.

            9.3.6.1 Check and adjust GC and/or MS operating conditions;
                    check the MS resolution, and calibrate the mass
                    scale.

            9.3.6.2 Prepare fresh CAL solutions, and repeat the initial
                    calibration step.

            9.3.6.3 Clean the MS ion source and rods (if a quadrupole).

            9.3.6.4 Replace the MS electron multiplier, or any other
                    faulty components.

9.4  Optional  calibration for vinyl chloride using a certified gaseous
     mixture of vinyl chloride in nitrogen can be accomplished by the
     following steps.

     9.4.1  Fill the purging device with 25.0 ml of reagent water or
            aqueous calibration standard.

     9.4.2  Start to purge the aqueous mixture.  Inject a known volume
            (between 100 and 2000 ill) of the calibration gas (at room
            temperature) directly into the purging device with a gas
            tight syringe.  Slowly inject the gaseous sample through a
            septum seal  at the top of the purging device at 2000 #L/min.
            If the injection of the standard is-made through the aqueous
            sample inlet part, flush the head volume with several  mL of
            room air or carrier gas.  Inject the gaseous standard before
            5  min of the 11-min purge time have elapsed.

     9.4.3  Determine the aqueous equivalent concentration of  vinyl
            chloride standard, in /jg/L,  injected with the equation:

                   S = 0.102 (C)(V)

            where  S = Aqueous equivalent concentration
                        of vinyl  chloride standard in /jg/L;
                   C - Concentration of gaseous standard in ppm (v/v);

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                        V = Volume of standard injected in milliliters.

10.   QUALITY CONTROL

     10.1 Quality control (QC) requirements are the initial demonstration of
          laboratory capability followed by regular analyses of laboratory
          reagent blanks, field reagent blanks, and laboratory fortified
          blanks.  The laboratory must maintain records to document the
          quality of the data generated. Additional quality control practices
          are recommended.

     10.2 Initial demonstration of low system background.   Before any samples
          are analyzed,  it  must be demonstrated that a laboratory reagent
          blank (LRB) is reasonably free of contamination  that would prevent
          the determination of any analyte of concern.  Sources  of background
          contamination  are glassware, purge gas,  sorbants, and  equipment.
          Background contamination must be reduced to an acceptable level
          before proceeding with the next section.  In general  background from
          method analytes should be below the method detection limit.

     10.3 Initial demonstration of laboratory accuracy and precision.  Analyze
          four to seven  replicates of a laboratory fortified blank containing
          each analyte of concern at a concentration in the range of
          0.2-5 jtig/L (see regulations and maximum  contaminant levels for
          guidance on appropriate concentrations).
       t
          10.3.1 Prepare each replicate by adding  an appropriate  aliquot of a
                 quality control  sample to reagent water.   If a  quality
                 control  sample containing the method analytes is not
                 available,  a primary dilution standard made from a source  of
                 reagents different than those used to prepare the calibration
                 standards  may be used.   Also add  the appropriate amounts  of
                 internal  standard and surrogates  if they  are being used.
                 Analyze each replicate according  to the procedures described
                 in Section 11,  and on a schedule  that results  in the  analyses
                 of all  replicates over a period of several  days.

          10.3.2 Calculate  the measured concentration of each analyte  in each
                 replicate,  the mean concentration of each analyte in  all
                 replicates,  and  mean accuracy (as mean percentage of  true
                 value)  for each  analyte,  and the  precision (as relative
                 standard deviation,  RSD)  of the measurements for each
                 analyte.   Calculate the MDL of each analyte using the
                 procedures described in Sect.  13.2 (2).

          10;3.3 For each analyte and surrogate, the mean  accuracy,  expressed
                 as a percentage  of the true value,  should be 80-120%  and the
                 RSD should be <20%.  Some analytes,  particularly  the early
                 eluting  gases and late eluting higher molecular  weight
                 compounds,  are measured with less accuracy and precision than
                 other analytes.   The method detection limits must be  suffici-
                 ent to  detect analytes  at  the  required levels.   If these

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            ent to detect analytes at the required levels.  If these
            criteria are not met for an analyte,  take remedial action and
            repeat the measurements for that analyte to demonstrate
            acceptable performance before samples are analyzed.

     10.3.4 Develop and maintain a system of control charts to plot the
            precision and accuracy of analyte and surrogate measurements
            as a function of time.  Charting of surrogate recoveries is
            an especially valuable activity since these are present in
           .every sample and the analytical results will  form a signi-
            ficant record of data quality.

10.4 Monitor the integrated areas of the quantitation ions of the
     internal standards and surrogates in continuing calibration checks.
     These should remain reasonably constant over time.  A drift of more
     than 50% in any area is indicative of a loss in sensitivity, and the
     problem must be found and corrected.  These integrated areas should
     also be reasonably constant in laboratory fortified blanks and
     samples.

10.5 LABORATORY REAGENT BLANKS.  With each batch of samples processed as
     a group within a work shift, analyze a laboratory reagent blank to
     determine the background system contamination.  A FRB (Sect. 10.7)
     may be used in place of an LRB.

10.6 With each batch of samples processed as a group within a work shift,
     analyze a single laboratory fortified blank (LFB) containing each
     analyte of concern at a concentration as determined in 10.3.  If
     more than 20 samples are included in a batch, analyze one LFB for
     every 20 samples.  Use the procedures described in 10.3.3 to
     evaluate the accuracy of the measurements, and to estimate whether
     the method detection limits can be obtained.  If acceptable accuracy
     and method detection limits cannot be achieved, the problem must be
     located and corrected before further samples are analyzed.   Add
     these results to the on-going control charts to document data
     quality.

10.7 With each set of field samples a field reagent blank (FRB)  should be
     analyzed.  The results of these analyses will help define contamina-
     tion resulting from field sampling and transportation activities.
     If the FRB shows unacceptable contamination, a LRB must be measured
     to define the source of the impurities.

10.8 At least quarterly, replicates of laboratory fortified blanks should
     be analyzed to determine the precision of the laboratory measure-
     ments.  Add these results to the on-going control charts to document
     data quality.

10.9 At least quarterly, analyze a quality control sample (QCS)  from an
     external source.  If measured analyte concentrations are not of
     acceptable accuracy, check the entire analytical procedure to locate
     and correct the problem source.

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    10.10 Sample matrix effects have not been observed when this method is
          used  with distilled water, reagent water,  drinking water,  and
          ground  water.  Therefore, analysis of a laboratory fortified sample
          matrix  (LFM) is not required.  It is recommended that sample matrix
          effects  be evaluated at least quarterly using the QCS described in
          10.9.

    10.11 Numerous other quality control measures are incorporated into other
          parts  of this procedure, and serve to alert the analyst to  potential
          problems.

11.  PROCEDURE

    11.1  SAMPLE INTRODUCTION AND PURGING — This method is designed  for a
          25-mL  sample volume, but a smaller (5 mL) sample volume is
          recommended if the GC/MS system has adequate sensitivity to achieve
          the required method detection limits.  Adjust the purge gas
          (nitrogen or helium) flow rate to 40 mL/min.  Attach the trap inlet
          to the purging device and open the syringe  valve on the purging
          device.

    11.2  Remove the plungers from two 25-mL (or 5-mL depending on sample
          size)  syringes and attach a closed syringe  valve to each.   Warm the
          sample to room temperature, open the sample bottle, and carefully
          pour the sample into one of the syringe barrels to just short of
          overflowing.  Replace the syringe plunger,  invert the syringe, and
          compress the sample.  Open the syringe valve and vent any residual
          air while adjusting the sample volume to 25.0 mL (or 5-mL).  For
          samples and blanks, add 10 #L of the fortification solution
          containing the internal standard and the surrogates to the  sample
          through the syringe valve.  For calibration standards and laboratory
          fortified blanks, add 10 #L of the fortification solution containing
          the internal standard only.  Close the valve.  Fill the second
          syringe in an identical manner from the same sample bottle.  Reserve
          this second syringe for a reanalysis if necessary.

    11.3  Attach the sample syringe valve to the syringe valve on the purging
          device.  Be sure that the trap is cooler than 25°C,  then open the
          sample syringe valve and inject the sample  into the purging chamber.
          Close  both valves and initiate purging.  Purge the sample for 11.0
          min at ambient temperature.

    11.4  SAMPLE DESORPTION — After the 11-min purge, place the purge and
          trap system in the desorb mode.  Introduce  the trapped materials to
          the GC column by rapidly heating the trap to 180°C while
          backflushing the trap with an inert gas at  15 mL/min for about 4.
          min.  Simultaneously with the start of desorption, begin the
          temperature program of the gas chromatograph, and start data
          acquisition.  While the extracted sample is being introduced into
          the gas chromatograph, empty the purging device using the sample
          syringe and wash the chamber with two 25-mL flushes of reagent
          water.  After the purging device has been emptied, leave syringe

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      valve open to allow the purge gas to vent through the sample
      Introduction needle.

11.5  GAS CHROMATOGRAPHY/MASS SPECTROMETRY — Acquire and store data from
      m/z 35-260 with a total cycle time (including scan overhead time) of
      7 sec or less.  Cycle time should be adjusted to measure at least
      five or more spectra during the elution of each GC peak.  Adjust the
      helium carrier gas flow rate to about 40 mL/min.  The column
      temperature is programmed to hold at 45°C for three min,  increase to
      2206C at 8°C/min,  and  hold  at 220°C for 15 min or until all expected
      compounds have eluted.

11.6  TRAP RECONDITIONING — After desorbing the sample for 4 min,
      recondition the trap by returning the purge and trap system to the
      purge mode.  Wait 15 sec, then close the syringe valve on the
      purging device to begin gas flow through the trap.  Maintain the
      trap temperature at 180°C.   After approximately 7 min,  turn off the
      trap heater and open the syringe valve to stop the gas flow through
      the trap.  When the trap is cool, the next sample can be analyzed.

11.7  TERMINATION OF DATA ACQUISITION — When all the sample components
      have eluted from the GC, terminate MS data acquisition.  Use
      appropriate data output software to display full range mass spectra
      and appropriate plots of ion abundance'as a function of time.  If
      any ion abundance exceeds the system working range, dilute the
      sample aliquot in the second syringe with reagent water and analyze
      the diluted aliquot.

11.8  IDENTIFICATION OF ANALYTES — Identify a sample component by compar-
      ison of its mass spectrum (after background subtraction)  to a
      reference spectrum in the user-created data base.  The GC retention
      time of the sample component should be within three standard
      deviations of the mean retention time of the compound in the
      calibration mixture.

      11.8.1 In general, all ions that are present above 10% relative
             abundance in the mass spectrum of the standard should be
             present in the mass spectrum of the sample component and
             should agree within absolute 20%.   For example,  if an ion has
             a relative abundance of 30% in the standard spectrum, its
             abundance in the sample  spectrum should be in the range of 10
             to 50%.  Some ions,  particularly the molecular ion,  are of
             special importance,  and  should be  evaluated even if they are
             below 10% relative abundance.

      11.8.2 Identification requires  expert judgement when sample
             components are not resolved chromatographically and produce
             mass spectra containing  ions contributed by more than one
             analyte.   When GC peaks  obviously  represent more than,one
             sample component (i.e.,  broadened  peak with shoulder(s) or
             valley between two or more maxima),  appropriate analyte
             spectra and background spectra can be selected by examining

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                 plots  of characteristic  ions  for  tentatively  identified
                 components.   When  analytes  coelute  (i.e.,  only  one  GC  peak is
                 apparent),  the  identification criteria  can be met but  each
                 analyte spectrum will  contain extraneous  ions contributed  by
                 the  coeluting compound.   Because  purgeable organic  compounds
                 are  relatively  small molecules and  produce comparatively
                 simple mass  spectra, this is  not  a  significant  problem for
                 most method  analytes.

          11.8.3 Structural  isomers that  produce very similar  mass spectra  can
                 be explicitly identified only if  they have sufficiently
                 different GC retention times.  Acceptable resolution  is
                 achieved if the height of the valley between  two peaks is
                 less than 25% of the average  height of  the two  peaks.
                 Otherwise,  structural  isomers are identified  as isomeric
                 pairs. Cis-  and trans-l,2-dichloroethene,  two of the  three
                 isomeric xylenes,  and  two of  the  three  dichlorobenzenes are
                 three  examples  of  structural  isomers that cannot be explicit-
                 ly identified if both  members of  the isomeric pair  are
                 present.  These groups of isomers must  be reported  as
                 isomeric pairs  (see Method 524.2  for an alternative
                 approach).

          11.8.4 Methylene chloride and other  background components  appear  in
                 variable quantities in laboratory and field reagent blanks,
                 and  generally cannot be  accurately  measured.  Subtraction  of
                 the  concentration  in the blank from the concentration  in the
                 sample is not acceptable because  the concentration  of the
                 background in the  blank  is highly variable.

12.  CALCULATIONS

    12.1  Complete chromatographic  resolution  is not necessary for accurate
          and precise measurements  of analyte  concentrations if  unique ions
          with adequate intensities are available  for quantitation.  For
          example, although two  listed  analytes, carbon  tetrachloride  and
          bromodichloromethane,  were not  resolved  with the GC  conditions used,
          concentrations were calculated  by measuring the non-interfering
          quantitation  ions.

          12.1.1 Calculate analyte  and  surrogate concentrations.
                         c   .      (Ax)(Qis) 1000

                                   (A,.) RF V

                 where:  Cx  =  concentration of  analyte  or  surrogate  in
                                    in the water sample.
                         Ax  =  integrated  abundance  of  the  quantitation  ion
                               of the analyte in the sample.
                         Ais  =  integrated  abundance of the quantitation  ion
                               of the internal  standard in  the sample.
                         Qis  =  total quantity (in micrograms) of internal

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                                standard  added to  the water  sample.
                          V    =  original  water sample volume  in ml.
                          RF   =  mean  response factor of analyte from the
                                initial calibration.

          12.1.2 Alternatively, use  the  GC/MS system software or other
                 available proven software to compute the concentrations  of
                 the analytes and surrogates from the second or third order
                 regression curves.

          12.1.3 Calculations should utilize all  available digits of
                 precision, but final reported concentrations should be
                 rounded  to an  appropriate number of significant figures  (one
                 digit of uncertainty).   Experience indicates that three
                 significant figures may be used  for concentrations above
                 99 fig/I, two significant figures for concentrations between
                 1-99 /Kj/L, and one  significant figure for lower concentra-
                 tions.

          12.1.4 Calculate the  total trihalomethane concentration by summing
                 the four individual trihalomethane concentrations in /*g/L.

13. ACCURACY AND PRECISION

    13.1  Single laboratory accuracy and precision data were obtained for 31
          of the method analytes using laboratory fortified blanks with
          analytes at concentrations between 1 and 5 /*g/L, and these data are
          shown in Table  3.

    13.2  With these data, method detection limits were calculated using  the
          formula (2):

                MDL = S t^^

                where:   t(n_., ,  lpha = Q-99)  = Student's t value  for the 99%
                          confidence level with n-1 degrees of freedom
                        n = number of replicates
                        S = the standard deviation of the replicate analyses.

14. REFERENCES

    1.   Alford-Stevens, A.,  J.W. Eichelberger,  W.L.  Budde, "Purgeable Organic
        Compounds in Water by Gas Chromatography/ Mass Spectrometry, Method
        524."  Environmental  Monitoring and Support Laboratory,  U.S.
        Environmental  Protection Agency,  Cincinnati,  Ohio, February 1983.

    2.   Glaser,  J.A.,  D.L. Foerst, G.D.  McKee,  S.A.  Quave, and W.L. Budde,
        "Trace Analyses for Wastewaters," Environ. Sci.  Techno!.,  15,  1426,
        1981.
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3.  "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, August, 1977.

4.  "OSHA Safety and Health Standards, General Industry," (29CFR1910),
    Occupational Safety and Health Administration, OSHA 2206, (Revised,
    January 1976).

5.  "Safety in Academic Chemistry Laboratories," American Chemical Society
    Publication, Committee on Chemical Safety, 3rd Edition, 1979.
                                  275

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               TABLE 1.  MOLECULAR WEIGHTS, RETENTION TIME DATA,
                   AND QUANTITATION IONS FOR METHOD ANALYTES
 Compound
MWa
Retention15    Primary
  Time     Quantitation
fmin:sec)       Ions
  Secondary
Quantitation
    Ions	
      Internal  standard

 Fluorobenzene                  96        16:34        96           77

      Surrogates

 4-Bromofluorobenzene          174        26:53        95           174,176
 l,2-Dichlorobenzene-d4       150       35:55       152          115,150

      Target Analvtes

 Benzene                        78        15:31        78           77
 Bromobenzene                  156        25:12       156           77,158
 Bromochloromethane            128        9:20       128           49,130
 Bromodichloromethane          162        12:24        83           85,'l27
 Bromoform                    250        17:17       173          175^252
 Bromomethane                   94                    94           96
 Carbon tetrachloride         152        12:19       117          119
 Chlorobenzene                112        22:14       112           77,114
 Chloroethane                   64                    64           66
 Chloroform                   118        9:41        83           85
 Chloromethane                  50           .         50     ,52
 2-Chlorotoluene              126                    91          126
 4-Chlorotoluene              126                    91          126
 Dibromochloromethane         206        14:53       129          127
 1,2-Dibromo-3-Chloropropane  234        23:55        75          155,157
 1,2-Dibromoethane            186        16:10       107          109,188
 Dibromomethane               172        10:38        93           95,174
 1,2-DiChlorobenzene          146       35:07       146          111,148
 1,3-DiChlorobenzene          146       35:55       146          111,148
 1,4-DiChlorobenzene          146       35:55       146          111,148
 Dichlorodifluoromethane      120        4:14        85           87
 1,1-DiChloroethane             98        9:02        63           65,83
 1,2-Dichloroethane             98        10:43        62           98
 1,1-Dichloroethene             96        7:50        96           61,63
cis-l,2-Dichloroethene         96                    96           61,98
trans-l,2-Dichloroethene       96        9:55        96           61,98
1,2-Dichloropropane          112       13:55        63          112*
1,3-Dichloropropane          112       16:28        76           78
2,2-Dichloropropane          112                    77           97
1,1-Dichloropropene          110                    75          110,77
cis-l,3-dichloropropene      110                    75
trans-l,3-dichloropropene    110                    75
Ethyl benzene                 106                    91          106
p-Isopropyltoluene           134                   119          134,91
                                     276

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Compound
                            TABLE 1.   (Continued)
MWa
Retention13    Primary
  Time     Quantitation
fmin:sec)       Ions
  Secondary
Quantitation
    Ions
Methyl ene chloride
Styrene
1,1,1, 2-Tetrachl oroethane
1,1,2, 2-Tetrachl oroethane
Tetrachloroethene
Toluene
1,1, 1-Tri chl oroethane
1,1, 2-Tri chl oroethane
Trichloroethene
Tr i chl orof 1 uoromethane
1,2, 3-Tr i chl oropropane
Vinyl Chloride
o-Xyl ene
m-Xylene
p-Xylene
84
104
166
166
164
92
132
132
130
136
146
62
106
106
106
5:21
29:02

19:31
20:00
21:22
11:41

14:43
7:22

4:00
30:34
30:48
30:48
84
104
131
83
166
92
97
83
95
101
75
62
106
106
106
86,49
78
133,119
131,85
168,129
91
99,61
97,85
130,132
103
77
64
91
91
91
   Monoisotopic  molecular  weight  calculated  from the  atomic  masses  of the
   isotopes  with the  smallest  masses.
   Retention time measured from the  beginning  of the  thermal  desorption  step.
   Compounds with no  retention data  are  known  to be amenable to  purge and trap
   extraction (see Method  524.2),  and  chromatography  on  the  packed  gas
   chromatography column used  in  this  method,  but no  retention time data is
   available for this method.
                                   277

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TABLE 2. ION ABUNDANCE CRITERIA FOR 4-BROMOFLUOROBENZENE (BFB)
 Mass
 (M/z)
Relative Abundance Criteria
  50
  75
  95
  96
 173
 174
 175
 176
 177
15 to 40% of mass 95
30 to 80% of mass 95
Base Peak, 100% Relative Abundance
5 to 9% of mass 95
< 2% of mass 174
> 50% of mass 95
5 to 9% of mass 174
> 95% but < 101% of mass 174
5 to 9% of mass 176
                             278

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 TABLE 3.   ACCURACY AND PRECISION DATA FROM SEVEN TO NINE DETERMINATIONS
                 OF THE METHOD ANALYTES IN REAGENT WATER3
True
Cone.
Compound (uq/L)
Benzene
Bromobenzene
Bromodi chl oromethane
Bromoform
Carbon tetrachloride
Chlorobenzene
Chloroform
Di bromochl oromethane
1 , 2-Di bromo-3-chl oropropane
1,2-Dibromoethane
Dibromomethane
1, 2-Di chlorobenzene
1 , 4-Di chl orobenzene
Di chl orodi f 1 uoromethane
1,1-Dichloroethane
1,2-Dichloroethane
1, 1-Dichloroethene
trans-1 , 2-Di chl oroethene
1 , 2-Di chl oropropane
1 , 3-Di chl oropropane
Methyl ene chloride
Styrene
1,1,2, 2-Tetrachl oroethane
Tetrachl oroethene
Toluene
1,1, 1-Tri chl oroethane
Tri chl oroethene
Tri chl orof 1 uoromethane
Vinyl chloride
o-Xylene
p-Xylene
1.0
1.0
1.0
2.5
1.0
1.0
1.0
1.0
3.5
1.0
1.0
5.0
5.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Mean Rel . Mean Method
Observed Std. Std. Accuracy Dect.
Cone. Dev. Dev. (% of True Limit
(UQ/L} (ua/L) (%) Value} (ua/l)
0.97
0.92
1.0
2.4
0.88
1.02
1.03
0.92
3.5
0.93
0.94
5.0
5.6
0.96
1.05
0.97
1.09
0.98
1.01
1.00
0.99
1.2
1.11
0.93
1.05
1.05
0.90
1.09
0.98
1.02
1.11
0.036
0.042
0.17
0.23
0.098
0.047
0.086
0.14
0.63
Q.13
0.11
0.35
0.73
0.11
0.060
0.077
0.066
0.066
0.060
0.033
0.45
0.072
0.14
0.10
0.043
0.093
0.12
0.072
0.11
0.068
0.047
3.7
4.6
17.
9.6
11.
4.6
8.3
15.
18.
14.
12.
7.0
13.
12.
5.7
7.9
6.1
6.7
5.9
3.3
46.
6.0
13.
11.
4.1
8.9
13.
6.6
11.
6.7
4.2
97
92
100
100
88
L02
103
92
100
93
94
100
112
9.6
105
97
109
98
101
100
99
120
111
93
105
105
90
109
98
102
111
0.1
0.1
0.5
0.7
0.3
0.1
0.2
0.4
2.
0.4
0.3
1.
2.
0.3
0.2
0.2
0.2
0.2
0.2
0.1
1.
0.2
0.4
0.3
0.1
0.3
0.4
0.2
0.3
0.2
0.3
Data obtained by Robert W. Slater with a 25-mL sample size and the
compounds divided into two groups to minimize coelution.
                                   279

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   OPTIONAL
   FOAM
   TRAP
EXIT X IN.
    0.0.

 14MU 0. D.
                   INLET K IN.
                        0.0.
0. D. EXIT
                      .SAMPLE INLET

                    -*-2-WAY SYRINGE VALVE
                    —-17CM. 20 GAUGE SYRINGE NEEDLE

                       6MM. 0. D. RUBBER SEPTUM
                               . 0. D.
                            INLET
                            K IN. 0. 0.
                    1/16 IN. O.D.
                    'STAINLESS ST
   10MM GLASS FRIT
   MEDIUM POROSITY
                                        13X MOLECULAR
                                        SIEVE PURGE
                                        GAS FILTER
                                           PURGE GAS

                                           CONTROL
              FIGURE 1.  PURGING DEVICE'
                        280

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     PACKING PROCEDURE
            CONSTRUCTION
    GLASS
    WOOL
ACTIVATED,,^
CHARCOAL.7-7CW
 GRADE 15
         7.7C
 SILICA GEL'




   TENAX 7.7 CM


3%OV-1    ,_„,
GLASS l"nni'°"
     !»00
     7A/FQOT
   RESISTANCE
  WIRE WRAPPED
     SOLID
(DOUBLE LAYER)
    7*./FOOTi
  RESISTANCE
 WIRE WRAPPED
       SOLID
(SINGLE LAYER)
        soH
                                       COMPRESSION
                                       FITTING NUT
                                       AND FERRULES


                                        THERMOCOUPLE/
                                        CONTROLLER
                                        SENSOR
             TRAP INLET
                                NIC
                             ERATURE
                             TROL
                            ID
                          PYROMETER
                                        TUBING 2SCM
                                        0.105 IN. I.D.
                                        0.125 IN. O.D.
                                        STAINLESS STEEL
     FIGURE 2.   TRAP PACKINGS AND CONSTRUCTION TO INCLUDE
                DESORB CAPABILITY
                       281

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COLUMN: 1% SP-1000 ON CARBOPACK:B
PROGRAM -45°C FOR 3 MIN, 8°C/MIN TO 220°C
DETECTOR: MASS SPECTROMETER
                        HI
                                                       I  . -  - t  .   «     I
                       10    12    U    16    18    20

                             RETENTION TIME. MIN.

                         FIGURE 3.  GAS CHROMATOGRAM
22    24    26   28
                                        282

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         METHOD 524.2.  MEASUREMENT OF PUR6EABLE ORGANIC COMPOUNDS  IN
        WATER BY CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY
                                 Revision 3.0
A. Alford-Stevens, J. W. Eichelberger, W. L. Budde - Method 524, Revision 1.0
(1983)

R. W. Slater, Jr. - Method 524.2, Revision 2.0 (1986)

J. W. Eichelberger, W. L. Budde - Method 524.2, Revision 3.0 (1989)
                 ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
                      OFFICE OF RESEARCH AND DEVELOPMENT
                     U.S.  ENVIRONMENTAL PROTECTION AGENCY
                           CINCINNATI, OHIO  45268
                                     283

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                                 METHOD 524.2

            MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY
            CAPILLARY  COLUMN  GAS  CHROMATOGRAPHY/MASS SPECTROMETRY
1.  SCOPE AND APPLICATION

    1.1  This is a general purpose method for the identification and
         simultaneous measurement of purgeable volatile organic compounds in
         finished drinking water, raw source water,  or drinking water in any
         treatment stage (1-2).  The method is applicable to a wide range of
         organic compounds, including the four trihalomethane disinfection
         by-products, that have sufficiently high volatility and low water
         solubility to be efficiently removed from water samples with purge
         and trap procedures.  The following compounds can be determined by
         this method.
              Compound

              Benzene
              Bromobenzene
              Bromochloromethane
              Bromodi chloromethane
              Bromoform
              Bromomethane
              n-Butylbenzene
              sec-Butyl benzene
              tert-Butylbenzene
              Carbon tetrachloride
              Chlorobenzene
              Chloroethane
              Chloroform
              Chloromethane
              2-Chlorotoluene
              4-Chlorotoluene
              Di bromochloromethane
              1,2-Di bromo-3-chloropropane
              1,2-Dibromoethane
              Dibromomethane
              1,2-Di chlorobenzene
              1,3-Di chlorobenzene
              1,4-Di chlorobenzene
              Di chlorodi f1uoromethane
              1,1-Dichloroethane
              1,2-Dichloroethane
              1,1-Dichloroethene
              ci s-1,2-Di chloroethene
              trans-1,2-Di chloroethene
              1,2-Dichloropropane

                                      284
Chemical Abstract Service
      Registry Number

          71-43-2
         108-86-1
          74-97-5
          75-27-4
          75-25-2
          74-83-9
         104-51-8
         135-98-8
          98-06-6
          56-23-5
         108-90-7
          75-00-3
          67-66-3
          74-87-3
          95-49-8
         106-43-4
         124-48-1
          96-12-8
         106-93-4
          74-95-3
          95-50-1
         541-73-1
         106-46-7
          75-71-8
          75-34-3
         107-06-2
          75-35-4
         156-59-4
         156-60-5
          78-87-5

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          1,3-Dichloropropane                      142-28-9
          2,2-Dichloropropane                      590-20-7
          1,1-Dichloropropene                      563-58-6
          cis-l,3-Dichloropropene                10061-01-5
          trahs-l,3-Dichloropropene              10061-02-6
          Ethyl benzene                             100-41-4
          Hexachlorobutadiene                       87-68-3
          Isopropylbenzene                          98-82-8
          4-Isopropyltoluene                        99-87-6
          Methylene chloride                        75-09-2
          Naphthalene                               91-20-3
          n-Propylbenzene                          103-65-1
          Styrene                                  100-42-5
          1,1,1,2-Tetrachloroethane                630-20-6
          1,1,2,2-Tetrachloroethane                 79-34-5
          Tetrachloroethene                        127-18-4
          Toluene                                  108-88-3
          1,2,3-Trichlorobenzene                    87-61-6
          1,2,4-Trichlorobenzene                   120-82-1
          1,1,1-Trichloroethane                     71-55-6
        -  1,1,2-Trichloroethane                     79-00-5
          Trichloroethene                           79-01-6
          Trichlorofluoromethane                    75-69-4
          1,2,3-Trichloropropane                    96-18-4
          1,2,4-Trimethyl benzene                    95-63-6
          1,3,5-Trimethyl benzene                   108-67-8
          Vinyl chloride                            75-01-4
          o-Xylene                                  95-47-6
          m-Xylene                                 108-38-3
          p-Xylene                                 106-42-3

1.2  Method detection limits (MDLs) (3) are compound and instrument
     dependent and vary from approximately 0.02-0.35 jag/L.   The applicable
     concentration range of this method is primarily column dependent and
     is approximately 0.02 to 200 /fg/L for the wide-bore thick-film
     columns. Narrow-bore thin-film columns may have a capacity which
     limits the range to about 0.02 to 20 /jg/L.  Analytes that are
     inefficiently purged from water will not be detected when present at
     low concentrations, but they can be measured with acceptable accuracy
     and precision when present in sufficient amounts.

1.3  Analytes that are not separated chromatographicallys but which have
     different mass spectra and non-interfering quantitation ions, can be
     identified and measured in the same calibration mixture or water
     sample (Sect 11.6.2).  Analytes which have very similar mass spectra
     cannot be individually identified and measured in the  same
     calibration mixture or water sample unless they have different
     retention times (Sect.11.6.3). Coeluting compounds with very similar
     mass spectra, typically many structural  isomers,  must  be reported as
     an isomeric group or pair.  Two of the three isomeric  xylenes and two
     of the three dichlorobenzenes are examples of structural  isomers that


                                  285

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     may not be resolved on the capillary column, and if not, must be
     reported as isomeric pairs.

SUMMARY OF METHOD

2.1  Volatile organic compounds and surrogates with low water solubility
     are extracted (purged) from the sample matrix by bubbling an inert
     gas through the aqueous sample.  Purged sample components are trapped
     in a tube containing suitable sorbent materials.  When purging is
     complete, the sorbent tube is heated and backflushed with helium to
     desorb the trapped sample components into a capillary gas
     chromatography (GC) column interfaced to a mass spectrometer (MS).
     The column is temperature programmed to separate the method analytes
     which are then detected with the MS.  Compounds eluting from the GC
     column are identified by comparing their measured mass spectra and
     retention times to reference spectra and retention times in a data
     base.  Reference spectra and retention times for analytes are
     obtained by the measurement of calibration standards under the same
     conditions used for samples.  The concentration of each identified
     component is measured by relating the MS response of the quantitation
     ion produced by that compound to the MS response of the quantitation
     ion produced by a compound that is used as an internal standard.
     Surrogate analytes, whose concentrations are known in every sample,
     are measured with the same internal standard calibration procedure.

DEFINITIONS

3.1  Internal standard — A pure analyte(s) added to a solution in known
     amount(s) and used to measure the relative responses of other method
     analytes and surrogates that are components of the same solution.
     The internal standard must be an analyte that is not a sample
     component.

3.2  Surrogate analyte — A pure analyte(s), which is extremely unlikely
     to be found in any sample, and which is added to a sample aliquot in
     known amount(s) before extraction and is measured with the same
     procedures used to measure other sample components.  The purpose of a
     surrogate analyte is to monitor method performance with each sample.

3.3  Laboratory duplicates (LD1 and LD2) — Two sample aliquots taken in
     the analytical laboratory and analyzed separately with identical
     procedures.  Analyses of LD1 and LD2 give a measure of the precision
     associated with laboratory procedures, but not with sample
     collection, preservation, or storage procedures.

3.4  Field duplicates (FD1 and FD2) — Two separate samples collected at
     the same time and place under identical circumstances and treated
     exactly the same throughout field and laboratory procedures.
     Analyses of FD1 and FD2 give a measure of the precision associated
     with sample collection, preservation and storage, as well as with
     laboratory procedures.
                                  286

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

 3.6  Field reagent blank (FRB)  — Reagent water placed in a sample
      container in  the laboratory and treated, as a sample in all  respects,
      including exposure to sampling  site conditions,  storage, preservation
      and  all  analytical  procedures.   The purpose of the  FRB is  to
      determine if  method analytes or other interferences are present  in
      the  field environment.

 3.7  Laboratory performance  check solution (LPC)  — A solution  of  one or
      more compounds (analytes,  surrogates,  internal  standard, or other
      test compounds)  used to evaluate the performance of the instrument
      system with respect to  a defined set of  method criteria.

 3.8  Laboratory fortified blank  (LFB)  — An aliquot of reagent water to
      which known quantities  of the method analytes  are added in  the
      laboratory.   The LFB is analyzed exactly like  a  sample,  and its
      purpose  is to determine whether the methodology  is  in  control, and
      whether  the laboratory  is capable of making  accurate and precise
      measurements  at  the required method detection  limit.

 3.9  Laboratory fortified sample  matrix  (LFM) — An aliquot  of an  environ-
      mental  sample to which  known quantities  of the method  analytes are
      added in  the  laboratory.  The LFM is  analyzed  exactly  like  a  sample,
      and  its  purpose  is  to determine  whether  the sample matrix contributes
      bias  to  the analytical  results.   The  background  concentrations of  the
      analytes  in the  sample  matrix must  be determined  in a  separate
      aliquot  and the  measured values  in  the LFM corrected for background
      concentrations.

 3.10  Stock standard solution — A concentrated solution containing a
      single certified standard that  is a method analyte, or  a, concentrated
      solution  of a  single analyte prepared in the laboratory with an
      assayed reference compound.  Stock  standard solutions  are used to
      prepare primary dilution standards.

 3.11  Primary dilution standard solution — A solution of several analytes
      prepared  in the laboratory from stock standard solutions and diluted
      as needed to prepare calibration solutions and other needed analyte
      solutions.

3.12 Calibration standard (CAL)  — A solution prepared from  the  primary
     dilution standard solution and stock standard solutions and the
      internal standards and surrogate analytes.   The CAL solutions  are
     used to calibrate the instrument response with respect  to analyte
     concentra-tion.
                                 287

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    3.13 Quality control sample (QCS) — A sample matrix containing method
         analytes or a solution of method analytes in a water miscible solvent
         which is used to fortify reagent water or environmental  samples.   The
         QCS is obtained from a source external to the laboratory,  and is  used
         to check laboratory performance with externally prepared test
         materi als.

4.  INTERFERENCES

    4.1  During analysis, major contaminant sources are volatile materials in
         the laboratory and impurities in the inert purging gas and in the
         sorbent trap.  The use of non-polytetrafluoroethylene (PTFE) plastic
         tubing, non-PTFE thread sealants, or flow controllers with rubber
         components in the purging device should be avoided since such
         materials out-gas organic compounds which will be concentrated in the
         trap during the purge operation.  Analyses of laboratory reagent
         blanks provide information about the presence of contaminants.  When
         potential interfering peaks are noted in laboratory reagent blanks,
         the analyst should change the purge gas source and regenerate the
         molecular sieve purge gas filter.  Subtracting blank values from
         sample results is not permitted.

    4.2  Interfering contamination may occur when a sample containing low
         concentrations of volatile organic compounds is analyzed immediately
         after a sample containing relatively high concentrations of volatile
         organic compounds.  A preventive technique is between-sample rinsing
         of the purging apparatus and sample syringes with two portions of
         reagent water.  After analysis of a sample containing high
         concentrations of volatile organic compounds, one or more laboratory
         reagent blanks should be analyzed to check for cross contamination.

    4.3  Special precautions must be taken to determine methylene chloride.
         The analytical and sample storage area should be isolated from all
         atmospheric sources of methylene chloride, otherwise random
         background levels will result.  Since methylene chloride will
         permeate through PTFE tubing, all gas chromatography carrier gas
         lines and purge gas plumbing should be constructed of stainless steel
         or copper tubing. Laboratory worker's clothing should be cleaned
         frequently since clothing previously exposed to methylene chloride
         fumes during common liquid/liquid extraction procedures can
         contribute to sample contamination.

5.  SAFETY

    5.1  The toxicity or carcinogenicity of chemicals used in this method has
         not been precisely defined; each chemical should be treated as a
         potential health hazard, and exposure to these chemicals should be
         minimized.  Each laboratory is responsible for maintaining awareness
         of OSHA regulations regarding safe handling of chemicals used in this
         method.  Additional references to laboratory safety are available
         (4-6) for the information of the analyst.


                                      288

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    5.2  The following method analytes have been tentatively classified as
         known or suspected human or mammalian carcinogens:  benzene, carbon
         tetrachloride, 1,4-dichlorobenzene, 1,2-dichlorethane, hexachloro-
         butadiene,1,1,2,2-tetrachloroethane, 1,1,2-trichloroethane, chloro-
         form, l,2-dibromoethane,tetrachloroethene, trichloroethene, and vinyl
         chloride.  Pure standard materials and stock standard solutions of
         these .compounds should be handled in a hood.  A NIOSH/MESA approved
         toxic gas respirator should be worn when the analyst handles high
         concentrations of these toxic compounds.

6.  APPARATUS AND EQUIPMENT

    6.1  SAMPLE CONTAINERS — 60-mL to 120-mL screw cap vials (Pierce #19832
         or equivalent) each equipped with a PTFE-faced silicone septum
         (Pierce #12718 or equivalent).  Prior to use, wash vials and septa
         with detergent and rinse with tap and distilled water.  Allow the
         vials and septa to air dry at room temperature, place in a 105°C oven
         for 1 hr, then remove and allow to cool  in an area known to be free
         of organics.

    6.2  PURGE AND TRAP SYSTEM — The purge and trap system consists of three
         separate pieces of equipment:  purging device,  trap, and desorber.
         Systems are commercially available from several sources that meet all
         of the following specifications.

         6.2.1   The all glass purging device (Figure 1) should be designed to
                 accept 25-mL samples with a water column at least 5 cm deep.
                 A smaller (5-mL) purging  device is recommended if the GC/MS
                 system has adequate sensitivity to obtain the method
                 detection limits required.  Gaseous volumes above the sample
                 must  be kept to a minimum (< 15 mL) to  eliminate dead volume
                 effects.   A glass frit should be installed at the base of the
                 sample chamber so the purge gas passes  through the water
                 column as finely divided  bubbles with a diameter of < 3 mm at
                 the origin.   Needle spargers may be used,  however,  the purge
                 gas must be introduced at a point about 5 mm from the base of
                 the water column.

         6.2.2   The trap (Figure 2)  must  be at least 25 cm long and have an
                 inside diameter of at least 0.105 in.   Starting from the
                 inlet, the trap should contain 1.0 cm of methyl  silicone
                 coated packing and the following amounts of adsorbents:   1/3
                 of 2,6-diphenylene oxide  polymer,  1/3 of silica gel,  and 1/3
                 of coconut charcoal.   If  it is not necessary to determine
                 dichlorodifluoromethane,  the charcoal can  be eliminated and
                 the polymer increased to  fill  2/3 of the trap.   Before
                 initial  use,  the trap should be  conditioned overnight at
                 180°C  by  backflushing with  an  inert gas  flow of at  least  20
                 mL/min.   Vent the  trap effluent  to the  room,  not  to the
                 analytical  column.   Prior to daily use,  the trap  should be
                 conditioned  for 10 min at 180°C with backflushing.  The trap
                 may be vented to the  analytical  column  during  daily

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             conditioning; however, the column must be run through the
             temperature program prior to analysis of samples.

     6.2.3   The use of the methyl silicone coated packing is recommended,
             but not mandatory.  The packing serves a dual purpose of
             protecting the Tenax adsorbant from aerosols, and also of
             insuring that the Tenax is fully enclosed within the heated
             zone of the trap thus eliminating potential  cold spots.
             Alternatively, silanized glass wool may be used as a spacer
             at the trap inlet.

     6.2.4   The desorber (Figure 2) must be capable of rapidly heating
             the trap to 180°C either prior to or at the  beginning of the
             flow of desorption gas.  The polymer section of the trap
             should not be heated higher than 200°C or the life expectancy
             of the trap will decrease.  Trap failure is characterized by
             a pressure drop in excess of 3 pounds per square inch across
             the trap during purging or by poor bromoform sensitivities.
             The desorber design illustrated in Fig. 2 meets these
             criteria.

6.3  GAS CHROMATOGRAPHY/MASS SPECTROMETER/DATA SYSTEM (GC/MS/DS)

     6.3.1   The GC must be capable of temperature programming and should
             be equipped with variable-constant differential flow
             controllers so that the column flow rate will remain constant
             throughout desorption and temperature program operation.  The
             column oven must be cooled to 10°C; therefore,  a subambient
             oven controller is required.  If syringe injections of BFB
             will be used, a split/splitless injection port is required.

     6.3.2   Capillary Gas Chromatography Columns.  Any gas chromatography
             column that meets the performance specifications of this
             method may be used.  Separations of the calibration mixture
             must be equivalent or better than those described in this
             method.  Three useful columns have been identified.

             6.3.2.1  Column 1 — 60 m x 0.75 mm ID VOCOL (Supelco, Inc.)
                      glass wide-bore capillary with a 1.5 iim film
                      thickness.

                      Column 2 -- 30 m x 0.53 mm ID DB-624 (J&W
                      Scientific, Inc.) fused silica capillary with a 3 /zm
                      film thickness.

                      Column 3 — 30 m x 0.32 mm ID DB-5  (J&W Scientific,
                      Inc.) fused silica capillary with a 1 urn film thick-
                      ness.

     6.3.3   Interfaces between the GC and MS.  The interface used depends
             on the column selected and the gas flow rate.
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        6.3.3.1  The wide-bore columns 1 and 2 have the capacity to
                 accept the standard gas flows from the trap during
                 thermal desorption, and chromatography can begin
                 with the onset of thermal desorption.  Depending on
                 the pumping capacity of the MS, an additional
                 interface between the end of the column and the MS
                 may be required.  An open split interface (7), an
                 all-glass jet separator, or a cryogenic (Sect.
                 6.3.3.2) device are acceptable interfaces.  Any
                 interface can be used if the performance
                 specifications described in this method can be
                 achieved.  The end of the transfer line after the
                 interface, or the end of the analytical column if no
                 interface is used, should be placed within a few mm
                 of the MS ion source.

        6.3.3.2  The narrow bore column 3 cannot accept the thermal
                 desorption gas flow, and a cryogenic interface is
                 required.  This interface (Tekmar Model 1000 or
                 equivalent) condenses the desorbed sample components
                 at liquid nitrogen temperature, and allows the
                 helium gas to pass through to an exit.  The
                 "condensed components are frozen in a narrow band on
                 an uncoated fused silica precolumn.  When all
                 components have been desorbed from the trap, the
                 interface is rapidly heated under a stream of
                 carrier gas to transfer the analytes to the
                 analytical column.  The end of the analytical column
                 should  be placed with a few mm of the MS ion
                 source.  A potential problem with this interface is
                 blockage of the interface by frozen water from the
                 trap.   This condition will  result in a major loss in
                 sensitivity and chromatographic resolution.

6.3.4   The mass spectrometer must be capable of electron ionization
        at a nominal electron energy of 70 eV.   The spectrometer must
        be capable of scanning from 35 to 260 amu with a complete
        scan cycle time (including scan overhead)  of 2 sec or less.
        (Scan cycle time = Total  MS data acquisition time in  seconds
        divided by number of scans in the chromatogram).  The
        spectrometer must produce a mass spectrum that meets  all
        criteria in Table 3 when 25 ng or less  of
        4-bromofluorobenzene (BFB)  is introduced into the GC.   An
        average spectrum across the BFB GC peak may be used to test
        instrument performance.

6.3.5   An interfaced data system is required to acquire,  store,
        reduce, and output mass spectral  data.   The computer  software
        should have the capability of processing stored GC/MS data by
        recognizing a GC peak within any given  retention time window,
        comparing the mass spectra from the  GC  peak with spectral
        data in a user-created data base,  and generating a  list of

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                 tentatively identified compounds with their retention times
                 and scan numbers.  The software must allow integration of the
                 ion abundance of any specific ion between specified time or
                 scan number limits.  The software should also allow
                 calculation of response factors as defined in Sect. 9.2.6 (or
                 construction of a second or third order regression
                 calibration curve), calculation of response factor statistics
                 (mean and standard deviation), and calculation of
                 concentrations of analytes using either the calibration curve
                 or the equation in Sect. 12.


    6.4  SYRINGE AND SYRINGE VALVES

         6.4.1   Two 5-mL or 25-mL glass hypodermic syringes with Luer-Lok tip
                 (depending on sample volume used).

         6.4.2   Three 2-way syringe valves with Luer ends.

         6.4.3   One 25-/JL micro syringe with a 2 in x 0.006 in ID, 22° bevel
                 needle (Hamilton #702N or equivalent).

         6.4.4   Micro syringes - 10, 100 #L.

         6.4.5   Syringes - 0.5, 1.0, and 5-mL, gas tight with shut-off valve.

    6.5  MISCELLANEOUS

         6.5.1   Standard solution storage containers — 15-mL bottles with
                 PTFE-lined screw caps.

7.  REAGENTS AND CONSUMABLE MATERIALS

    7.1  TRAP PACKING MATERIALS

         7.1.1   2,6-Diphenylene oxide polymer, 60/80 mesh, chromatographic
                 grade (Tenax GC or equivalent).

         7.1.2   Methyl silicone packing (optional) — OV-1 (3%) on Chromosorb
                 W, 60/80 mesh, or equivalent.

         7.1.3   Silica gel — 35/60 mesh, Davison, grade 15 or equivalent.

         7.1.4   Coconut charcoal — Prepare from Barnebey Cheney, CA-580-26
                 lot #M-2649 by crushing through 26 mesh screen.

    7.2  REAGENTS

         7.2.1   Methanol — Demonstrated to be free of analytes.

         7.2.2   Reagent water — Prepare reagent water by passing tap water
                 through a filter bed containing about 0.5 kg of activated

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        .  ... carbon, by using a water purification system, or by boiling
             distilled water for 15 min followed by a 1-h purge with inert
             gas while the water temperature is held at 90 C.  Store in
             clean, narrow-mouth bottles with PTFE-lined septa and screw
        .     caps.

     7.2.3   Hydrochloric acid (1+1) — Carefully add measured volume of
             cone. HC1 to equal volume of reagent water.

     7.2.4   Vinyl chloride — Certified mixtures of vinyl chloride in
             nitrogen and pure vinyl chloride are available from several
             sources (for example, Matheson, Ideal Gas Products, and Scott
             Gases).

     7.2.5   Ascorbic acid — ACS reagent grade, granular.

     7.2.6   Sodium thiosulfate — ACS reagent grade, granular.

7.3  STOCK STANDARD SOLUTIONS — These solutions may be purchased as
     certified solutions or prepared from pure standard materials using
     the following procedures.  One of these solutions is required for
     every analyte of concern, every surrogate, and the internal standard.
     A useful working concentration is about 1-5 mg/mL.

     7.3.1   Place about 9.8 ml of methanol into a 10-mL ground-glass
             stoppered volumetric flask.  Allow the flask to stand,
             unstoppered, for about 10 min or until  all  alcohol-wetted
             surfaces have dried and weigh to the nearest 0.1 mg.

     7.3.2   If the analyte is a liquid,at room temperature,  use a 100-/U.
             syringe and immediately add two or more drops of reference
             standard to the flask.  Be sure that the reference standard
             falls directly into the alcohol without contacting the neck
             of the flask.  If the analyte is a gas  at room temperature,
             fill a 5-mL valved gas-tight syringe with the standard to the
             5.0-mL mark, lower the needle to 5 mm above the methanol
             meniscus,  and slowly inject the standard into the neck area
             of the flask.  The gas will rapidly dissolve in the methanol.

     7.3.3   Reweigh,  dilute to volume,  stopper,  then mix by inverting the
             flask several times.   Calculate the concentration in vg/fiL
             from the net gain in weight.   When compound purity is
             certified at 96% or greater,  the weight can be used without
             correction to calculate the concentration of the stock
             standard.

     7.3.4   Store stock standard solutions in  15-mL bottles  equipped  with
             PTFE-lined screw caps.   Methanol  solutions  prepared from
             liquid analytes are stable  for at  least 4 weeks  when stored
             at 4°C.  Methanol solutions prepared from gaseous  analytes
.             are not stable for more than  1 week when  stored  at <0°C; at
;:-.-••       room temperature,  they must be discarded  after 1  day.

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7.4  PRIMARY DILUTION STANDARDS -- Use stock standard solutions to prepare
     primary dilution standard solutions that contain all the analytes of
     concern and the surrogates (but riot the internal standard!) in
     methanol.  The primary dilution standards should be prepared at
     concentrations that can be easily diluted to prepare aqueous calibra-
     tion solutions that will bracket the working concentration range.
     Store the primary dilution standard solutions with minimal headspace
     and check frequently for signs of deterioration or evaporation,
     especially just before preparing calibration solutions.  Storage
     times described for stock standard solutions in Sect. 7.4.4 also
     apply to primary dilution standard solutions.

7.5  FORTIFICATION SOLUTIONS FOR INTERNAL STANDARD AND SURROGATES

     7.5.1   A solution containing the internal standard and the
             surrogates is required to prepare laboratory reagent blanks
             (also used as a laboratory performance check solution), and
             to fortify each sample.  Prepare a fortification solution
             containing fluorobenzene (internal standard), 1,2-
             dichlorobenzene-d4 (surrogate),  and BFB (surrogate) in
             methanol at concentrations of 5 ng/ml of each (any
             appropriate concentration is acceptable).  A 5-/JL aliquot of
             this solution added to a 25-mL water sample volume gives
             concentrations of 1 #g/L of each.  A 5-juL aliquot of this
             solution added to a 5-mL water sample volume gives a
             concentration of 5 ng/L of each).  Additional internal
             standards and surrogate analytes are optional.

     7.5.2   A solution of the internal standard alone is required to
             prepare calibration standards and laboratory fortified
             blanks.  The internal standard should be in methanol at a
             concentration of 5 /jg/mL (any appropriate concentration is
             acceptable).

7.6  PREPARATION OF LABORATORY REAGENT BLANK — Fill a 25-mL (or 5-mL)
     syringe with reagent water and adjust to the mark (no air bubbles).
     Inject 10 /*L of the fortification solution containing the internal
     standard and surrogates through the Luer .Lok valve into the reagent
     water.  Transfer the LRB to the purging device.  See Sect. 11.1.2.

7.7  PREPARATION OF LABORATORY FORTIFIED BLANK — Prepare this exactly
     like a calibration standard (Sect. 7.8).  This is a calibration
     standard that is treated as a sample.                              .

7.8  PREPARATION OF CALIBRATION STANDARDS

     7.8.1   The number of calibration solutions (CALs) needed depends on
             the calibration range desired.  A minimum of three CAL
             solutions is required to calibrate a range of a factor of 20
             in concentration.  For a factor of 50, use at least four
             standards, and for a factor of 100 at least five standards.
             One calibration standard should contain each analyte of

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                 concern and each surrogate at a concentration of 2-10 times
       ;          the method detection limit (Tables 4-6) for that compound.
                 The other CAL standards should contain each analyte of
         ;       concern and each surrogate at concentrations that define the
                 range of the method.  Every CAL solution contains the
                 internal standard at the same concentration (5 ng/L suggested
                 for a 5-mL sample; 1 /ig/L for a 25-mL sample).

         7.8.2   To prepare a calibration standard, add an appropriate volume
                 of a primary dilution standard (containing analytes and
                 surrogates) to an aliquot of reagent water in a volumetric
                 flask.  Use a microsyringe and rapidly inject the methanol
                 solutions into the expanded area of the filled volumetric
                 flask.  Remove the needle as quickly as possible after
                 injection.  Mix by inverting the flask three times only.
                 Discard the contents contained in the neck of the flask.
           •. •. .  Aqueous standards are not stable in a volumetric flask and
                 should be discarded after 1 hr unless transferred to a sample
                 bottle and sealed immediately.

8.  SAMPLE COLLECTION. PRESERVATION. AND STORAGE

    8.1  SAMPLE COLLECTION, DECHLORINATION, AND PRESERVATION

         8.1.1   Collect all samples in duplicate.  If samples contain
                 residual chlorine, and measurements of the concentrations of
                 disinfection by-products (trihalomethanes, etc.) at the time
                 of sample collection are desired, add about 25 mg of ascorbic
                 acid to the sample bottle before filling.   If gases are not
          -       to be determined, sodium thiosulfate may be used to reduce
         -,'.-:    the residual chlorine.  Fill  sample bottles to overflowing,
                 but take care not to flush out the rapidly dissolving
                 ascorbic acid.  No air bubbles should pass through the sample
                 as the bottle is filled, or be trapped in  the sample when the
                 bottle is sealed.  Adjust the pH of the duplicate samples to
                 <2 by carefully adding one drop of 1:1 HC1 for each 20 mL of
                 sample volume.  Seal  the sample bottles,  PFTE-face down, and
                 shake vigorously for 1 min.                  .

         8.1.2   When sampling from a water tap,  open the tap and allow the
                 system to flush until  the water temperature has stabilized
                 (usually about 10 min).   Adjust the flow to about 500 mL/min
                 and collect duplicate samples from the flowing stream.

         8.1.3   When sampling from an open body of water,  fill  a 1-quart
                 wide-mouth bottle or 1-liter  beaker with  sample from a
                 representative area,  and carefully fill  duplicate sample
                 bottles from the 1-quart container.

         8.1.4   The samples must be chilled  to 4°C  on  the  day of collection
               ••  and maintained at that temperature until  analysis.   Field
                 samples that will not be received at the  laboratory on the
                 day of collection must be packaged for shipment with

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                 sufficient ice to ensure that they will be at 4°C on arrival
                 at the laboratory.
    8.2  SAMPLE STORAGE

         8.2.1   Store samples at 4°C until  analysis.   The sample storage area
                 must be free of organic solvent vapors.

         8.2.2   Analyze all samples within 14 days of collection.  Samples
                 not analyzed within this period must be discarded and
                 replaced.

    8.3  FIELD REAGENT BLANKS
         8.3.1
         8.3.2
9.  CALIBRATION
Duplicate field reagent blanks must be handled along with
each sample set, which is composed of the samples collected
from the same general sample site at approximately the same
time.  At the laboratory, fill field blank sample bottles
with reagent water, seal, and ship to the sampling site along
with empty sample bottles and back to the laboratory with
filled sample bottles.  Wherever a .set of samples is shipped
and stored, it is accompanied by appropriate blanks.

Use the same procedures used for samples to add ascorbic acid
and HC1 to blanks (Sect. 8.1.1).
    9.1  Demonstration and documentation of acceptable initial calibration is
         required before any samples are analyzed and is required
         intermittently throughout sample analysis as dictated by results of
         continuing calibration checks.  After initial calibration is
         successful, a continuing calibration check is required at the
         beginning of each 8 hr. period during which analyses are performed.
         Additional periodic calibration checks are good laboratory practice.

    9.2  INITIAL CALIBRATION

         9.2.1   Calibrate the mass and abundance scales of the MS with
                 calibration compounds and procedures prescribed by the
                 manufacturer with any modifications necessary to meet the
                 requirements in Sect. 9.2.2,

         9.2.2   Introduce into the GC (either by purging a laboratory reagent
                 blank or making a syringe injection) 25 ng of BFB and acquire
                 mass spectra for m/z 35-260 at 70 eV (nominal).  Use the
                 purging procedure and/or GC conditions given in Sect. 11.  If
                 the spectrum does not meet all criteria in Table 2,  the MS
                 must be retuned and adjusted to meet all criteria before
                 proceeding with calibration.  An average spectrum across the
                 GC peak may be used to evaluate the performance of the
                 system.

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9.2.3


9.2.4
        Purge a medium CAL solution, for example 10-20 fig/I, using
        the procedure given in Sect. 11.
Performance criteria for the medium calibration.
stored GC/MS data with the data system software.
shows an acceptable total ion chromatogram.
                                                          Examine the
                                                          Figure 3
        9.2.4.1  GC performance.  Good column performance will
                 produce symmetrical peaks with minimum tailing for
                 most compounds.  If peaks are broad, or sensitivity
                 poor, see Sect. 9.3.6 for some possible remedial
                 actions.

        9.2.4.2  MS sensitivity.  The GC/MS/DS peak identification
                 software should be able to recognize a GC peak in
                 the appropriate retention time window for each of
                 the compounds in calibration solution, and make
                 correct tentative identifications.  If fewer than
                 99% of the compounds are recognized, system
                 maintenance is required.  See Sect. 9.3.6.

9.2.5   If all performance criteria are met, purge an aliquot of each
        of the other CAL solutions using the same GC/MS conditions.

9.2.6   Calculate a response factor (RF) for each analyte, surrogate,
        and isomer pair for each CAL solution using the internal
        standard fluorobenzene.  Table 1 contains suggested
        quantitation ions for all compounds.  This calculation is
        supported in acceptable GC/MS data system software (Sect.
        6.3.4), and many other software programs.  RF is a unit! ess
        number, but units used to express quantities of analyte and
        internal standard must be equivalent.

                 RF=  (AX)(Q,-S)
where:   Ax  = integrated abundance of the quantitation ion
                of the analyte.
               integrated abundance of the quantitation ion
                of the internal standard.
               quantity of analyte purged in ng or
                concentration units.
               quantity of internal  standard purged  in  ng  or
                concentration units.
                 Ajs =

                 Qx  =
                  is
        9.2.6.1  For each analyte and surrogate, calculate the mean
                 RF from the analyses of the CAL solutions.
                 Calculate the standard deviation (SD) and the
                 relative standard deviation (RSD) from each mean:
                 RSD = 100 (SD/M).  If the RSD of any analyte or
                 surrogate mean RF exceeds 20%, either analyze
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                      additional aliquots of appropriate CAL solutions to
                      obtain an acceptable RSD of RFs over the entire
                      concentration range, or take action to improve 6C/MS
                      performance.  See Sect. 9.2.7.

     9.2.7   As an alternative to calculating mean response factors and
             applying the RSD test, use the GC/MS data system software or
             other available software to generate a second or third order
             regression calibration curve.

9.3  Continuing calibration check.  Verify the MS tune and initial
     calibration at the beginning of each 8-hr work shift during which
     analyses are performed using the following procedure.

     9.3.1   Introduce into the GC (either by purging a laboratory reagent
             blank or making a syringe injection) 25 ng of BFB and acquire
             a mass spectrum that includes data for m/z 35-260.   If the
             spectrum does not meet all criteria (Table 2), the  MS must be
             retuned and adjusted to meet all criteria before proceeding
             with the continuing calibration check.

     9.3.2   Purge a medium concentration CAL solution and analyze with
             the same conditions used during the initial  calibration.

     9.3.3   Demonstrate acceptable performance for the criteria shown in
             Sect. 9.2.4.

     9.3.4   Determine that the absolute areas of the quantitation ions of
             the internal  standard and surrogates have not decreased by
             more than 30% from the areas measured in the most recent
             continuing calibration check, or by more than 50% from the
             areas measured during initial calibration.   If these areas
             have decreased by more than these amounts,  adjustments must
             be made to restore system sensitivity.  These adjustments may
             require cleaning of the MS ion source, or other maintenance
             as indicated  in Sect.  9.3.6, and recalibration.   Control
             charts are useful  aids in documenting system sensitivity
             changes.

     9.3.5   Calculate the RF for each analyte and surrogate from the  data
             measured in the continuing calibration check.   The  RF for
             each analyte  and surrogate must be within 30% of the mean
             value measured in the initial calibration.   Alternatively,  if
             a second or third order regression is used,  the point from
             the continuing calibration check for each analyte and
             surrogate must fall,  within the analyst's judgement,  on the
             curve from the initial  calibration.   If these conditions  do
             not exist,  remedial  action must be taken which may  require
             re-initial  calibration.
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     9.3.6   Some possible  remedial  actions.  Major maintenance  such as
             cleaning  an  ion  source, cleaning quadrupole  rods, etc.
             require returning to  the  initial calibration step.

             9.3.6.1   Check and  adjust GC  and/or MS operating conditions;
                       check the  MS resolution,  and calibrate the mass
                       scale.

             9.3.6.2   Clean or replace the split!ess  injection liner;
                       silanize a new injection  liner.

             9.3.6.3   Flush the  GC column  with  solvent  according to manu-
                       facturer's instructions.

             9.3.6.4   Break off  a  short portion (about  1  meter)  of the
                       column  from  the  end  near  the injector; or  replace  GC
                       column.  This  action will cause a change in
                       retention  times.

             9.3.6.5   Prepare fresh  CAL solutions, and  repeat the  initial
                       calibration  step.

             9.3.6.6   Clean the  MS ion source and rods  (if a quadrupole).

             9.3.6.7   Replace any  components that allow analytes to come
                       into  contact with hot metal surfaces.

             9.3.6.8   Replace the  MS electron multiplier, or any other
                       faulty  components.

 9.4  Optional  calibration for vinyl  chloride using a  certified gaseous
     mixture of vinyl  chloride in  nitrogen can  be accomplished by  the
     following steps.

     9.4.1   Fill the  purging device with  25.0  ml (or 5-mL) of reagent
:             water  or  aqueous calibration  standard.

     9.4.2   Start  to  purge the  aqueous mixture.  Inject  a known volume
              (between  100 and 2000 /iL) of  the calibration gas  (at  room
             temperature) directly into the purging device with  a  gas
             tight  syringe.  Slowly  inject the  gaseous  sample through a
             septum seal  at the  top  of the purging device at 2000  /nL/min.
              If the injection of the standard is made through the  aqueous
             sample inlet port,  flush  the  dead  volume with several ml of
             room air  or  carrier gas.   Inject the gaseous standard before
             5 min  of  the 11-min purge time have elapsed.

     9.4.3   Determine the  aqueous equivalent concentration of vinyl
             chloride  standard,  in vg/L, injected with  the equation:

                       S = 0.102  (C)(V)


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                 where
S = Aqueous equivalent concentration
     of vinyl chloride standard in jug/L;
C = Concentration of gaseous standard in ppm (v/v);
V = Volume of standard injected in milliliters.
10. QUALITY CONTROL
    10.1 Quality control (QC) requirements are the initial  demonstration of
         laboratory capability followed by regular analyses of laboratory
         reagent blanks, field reagent blanks, and laboratory fortified
         blanks.  The laboratory must maintain records to document the quality
         of the data generated.  Additional  quality control practices are
         recommended.

    10.2 Initial demonstration of low system background.   Before any samples
         are analyzed, it must be demonstrated that a laboratory reagent blank
         (LRB) is reasonably free of contamination that would prevent the
         determination of any analyte of concern.   Sources  of background
         contamination are glassware, purge gas,  sorbants,  and equipment.
         Background contamination must be reduced to an acceptable level
         before proceeding with the next section.   In general, background from
         method analytes should be below the method detection limit.

    10.3 Initial demonstration of laboratory accuracy and precision.  Analyze
         five to seven replicates of a laboratory fortified blank containing
         each analyte of concern at a concentration in the  range of 0.2-5 /tg/L
         (see regulations and maximum contaminant levels  for guidance on
         appropriate concentrations).

         10.3.1  Prepare each replicate by adding an appropriate aliquot of a
                 quality control sample to reagent water.  If a quality
                 control sample containing the method analytes is not
                 available,  a primary dilution standard made from a source of
                 reagents different than those used to prepare the calibration
                 standards may be used.  Also add the appropriate amounts of
                 internal standard and surrogates if they are being used.
                 Analyze each replicate according to the  procedures described
                 in Section  11, and on a schedule that results in the analyses
                 of all  replicates over a period  of several days.

         10.3.2  Calculate the measured concentration of  each analyte in each
                 replicate,  the mean concentration of each  analyte in all
                 replicates,  and mean accuracy (as mean percentage of true
                 value)  for  each analyte,  and the precision (as relative
                 standard deviation, RSD)  of the  measurements for each
                 analyte.  Calculate the MDL of ea.ch analyte using the
                 procedures  described in Sect. 13.2 (2).

         10.3.3  For each analyte and surrogate,  the mean accuracy,  expressed
                 as a percentage of the true value,  should  be 80-120% and the
                 RSD should  be <20%.  Some analytes,  particularly the early
                 eluting gases and late eluting higher molecular weight

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             compounds,  are measured with less accuracy and precision than
             other analytes.  The method detection limits must be
             sufficient  to detect analytes at the required levels.   If
             these criteria are not met for an analyte, take remedial
             action and  repeat the measurements for that analyte to
             demonstrate acceptable performance before samples are
             analyzed.

     10.3.4  Develop and maintain a system of control  charts to plot the
             precision  and accuracy of analyte and surrogate measurements
             as a function of time.  Charting of surrogate recoveries is
             an especially valuable activity since these are present in
             every sample and the analytical results will form a
             significant record of data quality.

10.4 Monitor the integrated areas of the quantitation ions of the internal
     standards and surrogates in continuing calibration checks.  These
     should remain reasonably constant over time.  A drift of more  than
     50% in any area is  indicative of a loss in sensitivity, and the
     problem must be found and corrected.  These integrated areas should
     also be reasonably constant in laboratory fortified blanks and
     samples.

10.5 Laboratory reagent blanks.  With each batch of samples processed as a
     group within a work shift, analyze a laboratory reagent blank  to
     determine the background system contamination.  A FRB (Sect. 10.7)
     may be used in place of a LRB.

10.6 With each batch of samples processed as a group within a work  shift,
     analyze a single laboratory fortified blank (LFB) containing each
     analyte of concern at a concentration as determined in 10.3.  If more
     than 20 samples are included in a batch, analyze one LFB for every 20
     samples.  Use the procedures described in 10.3.3 to evaluate the
     accuracy of the measurements, and to estimate whether the method
     detection limits can be obtained.  If.acceptable accuracy and  method
     detection limits cannot be achieved, the problem must be located and
     corrected before further samples are analyzed.  Add these results to
     the on-going control charts to document data quality.

10.7 With each set of field samples a field reagent blank (FRB) should be
     analyzed.  The results of these analyses will help define contamina-
     tion resulting from field sampling and transportation activities.  If
     the FRB shows unacceptable contamination, a LRB must be measured to
     define the source of the impurities.

10.8 At least quarterly, replicates of laboratory fortified blanks  should
     be analyzed to determine the precision of the laboratory measure-
     ments.  Add these results to the on-going control charts to document
     data quality.

10.9 At least quarterly, analyze a quality control sample (QCS) from an
     external source.  If measured analyte concentrations are not of

                                  301

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         acceptable accuracy, check the entire analytical procedure to locate
         and correct the problem source.

   10.10 Sample matrix effects have not been observed when this method is used
         with distilled water, reagent water, drinking water, and ground
         water.  Therefore, analysis of a laboratory fortified sample matrix
         (LFM) is not required.  It is recommended that sample matrix effects
         be evaluated at least quarterly using the QCS described in 10.9.

   10.11 Numerous other quality control measures are incorporated into  other
         parts of this procedure, and serve to alert the analyst to potential
         problems.

11.  PROCEDURE

    11.1 SAMPLE INTRODUCTION AND PURGING

         11.1.1  This method is designed for a 25-mL sample volume, but a
                 smaller (5 ml) sample volume is recommended if the GC/MS
                 system has adequate sensitivity to achieve the required
                 method detection limits.   Adjust the purge gas (nitrogen or
                 helium) flow rate to 40 mL/min.  Attach the trap inlet to the
                 purging device and open the syringe valve on the purging
                 device.

         11.1.2  Remove the plungers from two 25-mL (or 5-mL depending on
                 sample size) syringes and attach a closed syringe valve to
                 each.   Warm the sample to room temperature,  open the sample
                 bottle, and carefully pour the sample into one of the syringe
                 barrels to just short of overflowing.   Replace the syringe
                 plunger,  invert the syringe,  and compress the sample.   Open
                 the syringe valve and vent any residual  air while adjusting
                 the sample volume to 25.0-mL (or 5-mL).   For samples and
                 blanks, add 5-#L (or an appropriate volume)  of the
                 fortification solution containing the internal  standard and
                 the surrogates to the sample through the syringe valve.   For
                 calibration standards and laboratory fortified blanks,  add
                 5-#L of the fortification solution containing the internal
                 standard  only.   Close the valve.   Fill  the second syringe in
                 an  identical  manner from  the same sample bottle.   Reserve
                 this second syringe for a reanalysis if necessary.

         11.1.3  Attach the sample syringe valve to the  syringe valve on  the
                 purging device.   Be sure  that  the trap  is cooler than  25°C,
                 then open  the sample syringe  valve and  inject the sample into
                 the purging chamber.   Close  both  valves  and  initiate purging.
                 Purge  the  sample for 11.0 min  at  ambient temperature.

   11.2  SAMPLE DESORPTION

         11.2.1   Non-cryogenic interface — After  the  11-min  purge, place  the
                 purge  and  trap  system in  the desorb  mode and  preheat the  trap

                                     302

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             to 180°C without a flow of desorption  gas.   Then simultan-
             eously start the flow of desorption gas at 15-mL/min for
             about 4 min, begin the temperature program of the gas
             chromatograph, and start data acquisition.

     11.2.2  Cryogenic interface — After the 11-min purge, place the
             purge and trap system in the desorb mode, make sure the
             cryogenic interface is a -150°C  or lower,  and rapidly heat
             the trap to 180°C while backflushing with an inert gas at
             4 mL/min for about 5 min.  At the end  of the 5 min desorption
             cycle, rapidly heat the cryogenic trap to 250°C,  and
             simultaneously begin the temperature program of the gas
             chromatograph, and start data acquisition.

     11.2.3  While the trapped components are being introduced into the
             gas chromatograph (or cryogenic interface), empty the purging
             device using the sample syringe and wash the chamber with two
             25-mL flushes of reagent water.   After the purging device has
             been emptied, leave syringe valve open to allow the purge gas
             to vent through the sample introduction needle.

11.3 GAS CHROMATOGRAPHY/MASS SPECTROMETRY — Acquire and store data over
     the nominal mass range 35-260 with a total cycle time (including scan
     overhead time) of 2 sec or less.  If water, methanol, or carbon
     dioxide cause a background problem, start at 47 or 48 m/z.  Cycle
     time must be adjusted to measure five or more  spectra during the
     elution of each GC peak. Several alternative temperature programs can
     be used.

     11.3.1  Single, ramp linear temperature program for wide bore columns
             1 and 2 with a jet separator.  Adjust  the helium carrier gas
             flow rate to about 15 mL/min.  The column temperature is
             reduced 10°C and held for 5 min  from the beginning of
             desorption, then programmed to 160°C at 6°C/min,  and  held
             until all components have eluted.

     11.3.2  Multi-ramp linear temperature program  for wide bore column 2
             with the open split interface.  Adjust the helium carrier gas
             flow rate to about 4.6 mL/min.,  The column temperature is
             reduced 10°C and held for 6 min  from the beginning of
             desorption, then heated to 70°C  at 10°/min,  heated to  120°C
             at 5°/min,  heated to 180°  at 8°/min, and held at 180° until
             all compounds have eluted.

     11.3.3  Single ramp linear temperature program for narrow bore column
             3 with a cryogenic interface.  Adjust  the helium carrier gas
             flow rate to about 4 mL/min.  The column temperature is
             reduced 10°C and held for 5 min  from the beginning of
             vaporization from the cryogenic trap,  programmed at 6°C/min
             for 10 min, then 15°C/nrin  for 5  min to 145°C, and  held until
             all components have eluted.


                                  303

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11.4 TRAP RECONDITIONING — After desorbing the sample for 4 min,
     recondition the trap by returning the purge and trap system to the
     purge mode.  Wait 15 sec, then close the syringe valve on the purging
     device to begin gas flow through the trap.  Maintain the trap
     temperature at 180°C.   After approximately 7 min,  turn off the trap
     heater and open the syringe valve to stop the gas flow through the
     trap.  When the trap is cool, the next sample can be analyzed.

11.5 TERMINATION OF DATA ACQUISITMN — When all the sample components
     have eluted from the GC, terminate MS data acquisition.  Use
     appropriate data output software to display full range mass spectra
     and appropriate plots of ion abundance as a function of time.  If any
     ion abundance exceeds the system working range, dilute the sample
     aliquot in the second syringe with reagent water and analyze the
     diluted aliquot.

11.6 IDENTIFICATION OF ANALYTES — Identify a sample component by
     comparison of its mass spectrum (after background subtraction) to a
     reference spectrum in the user-created data base.   The GC retention
     time of the sample component should be within three standard
     deviations of the mean retention time of the compound in the
     calibration mixture.

     11.6.1  In general, all ions that are present above 10% relative
             abundance in the mass spectrum of the standard should be
             present in the mass spectrum of the sample component and
             should agree within absolute 20%.  For example, if an ion has
             a relative abundance of 30% in the standard spectrum, its
             abundance in the sample spectrum should be in the range of 10
             to 50%.  Some ions, particularly the molecular ion, are of
             special importance, and should be evaluated even if they are
             below 10% relative abundance.

     11.6.2  Identification requires expert judgement when sample
             components are not resolved chromatographically and produce
             mass spectra containing ions contributed by more than one
             analyte.  When GC peaks obviously represent more than one
             sample component (i.e., broadened peak with shoulder(s) or
             valley between two or more maxima), appropriate analyte
             spectra and background spectra can be selected by examining
             plo.ts of characteristic ions for tentatively identified
             components.  When analytes coelute (i.e.,  only one GC peak is
             apparent), the identification criteria can be met but each
             analyte spectrum will  contain extraneous ions contributed by
             the coeluting compound.  Because purgeable organic compounds
             are relatively small  molecules and produce comparatively
             simple mass spectra,  this is not a significant problem for
             most method analytes.

     11.6.3  Structural isomers that produce very similar mass spectra can
             be explicitly identified only if they have sufficiently
             different GC retention times.  Acceptable  resolution is

                                 304

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                 achieved if the height of the valley between two peaks is
                 less than 25% of the average height of the two peaks.
                 Otherwise,  structural  isomers are identified as isomeric
                 pairs.   Two of the three isomeric xylenes and two of the
                 three dichlorobenzenes are examples of structural isomers
                 that may not be resolved on the capillary columns.   If
                 unresolved, these groups of isomers must be reported as
                 isomeric pairs.

         11.6.4  Methylene chloride and other background components  appear in
                 variable quantities in laboratory and field reagent blanks,
                 and generally cannot be accurately measured.  Subtraction of
                 the concentration in the blank from the concentration in the
                 sample is not acceptable because the concentration  of the
                 background in the blank is highly variable.

12.  CALCULATIONS

    12.1 Complete chromatographic resolution is not necessary for accurate and
         precise measurements of analyte concentrations if unique ions with
         adequate intensities are available for quantitation.


         12.1.1  Calculate analyte and surrogate concentrations.

                          c  =   (Ax)(Qis) 1000
                                   (A,.)  RF V
                 where:    Cx  = concentration  of analyte or surrogate in fig/L
                                  in the water sample.
                          Ax  = integrated abundance of the quantitation ion
                                  of the analyte in the sample.
                          Ais  =  integrated abundance  of  the  quantitation  ion
                                  of the internal standard in the sample.
                          Q1s  =  total quantity  (in micrograms)  of  internal
                                  standard added to the water sample.
                          V   = original water sample volume in ml.
                          RF  = mean response factor of analyte from the
                                  initial calibration.

         12.1.2  Alternatively, use the GC/MS system software or other
                 available proven software to compute the concentrations of
                 the analytes and surrogates from the second or third order
                 regression curves.

         12.1.3  Calculations should utilize all available digits of precis-
                 ion, but final reported concentrations should be rounded to
                 an appropriate number of significant figures (one digit of
                 uncertainty).  Experience indicates that three significant
                 figures may be used for concentrations above 99 /tg/L,  two
                 significant figures for concentrations between 1- 99 /zg/L,
                 and one significant figure for lower concentrations.

                                     305

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         12.1.4  Calculate the total trihalomethane concentration  by  summing
                 the four individual trihalomethane concentrations in
13. ACCURACY AND PRECISION

    13.1 Single laboratory accuracy and precision data were obtained  for the
         method analytes using laboratory fortified blanks with analytes at
         concentrations between 1 and 5 ng/L.  Four sets of results were
         obtained using the three columns specified (Sect. 6.3.2) and the open
         split, cryogenic, and jet separator interfaces (Sect. 6.3.3).  These
         data are shown in Tables 4-6.

    13.2 With these data, method detection limits were calculated using the
         formula (2):

         MDL - S t(n.1f1.alpha = 0_99)


         where:

         tovi.t-aipha = 0.99) = Student's  t  val ue for the  99%  confidence
                                  level with n-1 degrees of freedom,

         n = number of replicates

         S = the standard deviation of the
              replicate analyses.

14. REFERENCES

    1.   A. Al ford-Stevens, J.W. Eichelberger,  W.L. Budde, "Purgeable Organic
         Compounds in Water by Gas Chromatography/Mass Spectrometry,  Method
         524."  Environmental Monitoring and Support Laboratory, U.S.
         Environmental Protection Agency, Cincinnati, Ohio, February  1983.

    2.   Madding, C., "Volatile Organic Compounds in Water by Purge and Trap
         Capillary Column GC/MS", Proceedings of the Water Quality Technology
         Conference,  American Water Works Association, Denver, CO, December,
         1984.

    3.   Glaser, J.A., D.L. Foerst,  G.D. McKee, S.A. Quave, and W.L.  Budde,
         "Trace Analyses for Wastewaters, "Environ. Sci. Techno! . . 15, 1426,
         1981.                                                     ~

    4.   "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, August, 1977.

    5.   "OSHA Safety and Health Standards, General Industry," (29CFR1910),
         Occupational Safety and Health Administration, OSHA 2206, (Revised,
         January 1976).

                                      306

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

7.   Arrendale, R.F., R.F. Severson, and O.T. Chortyk, "Open Split
     Interface for Capillary Gas Chromatography/Mass Spectrometry", Anal.
     Chem. 1984, 56, 1533.

8.   Flesch, J.J., P.S. Fair, "The Analysis of Cyanogen Chloride in
     Drinking Water," Proceedings of Water Quality Technology Conference,
     American Water Works Association, St. Louis, MO., November 14-16,
     1988.
                                  307

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     TABLE 1.  MOLECULAR WEIGHTS AND QUANTITATION IONS FOR METHOD ANALYTES
Compound
MWa
    Primary
 Quantitation
	Ion
  Secondary
Quantitation
    Ions
      Internal  standard

 Fluorobenzene                96

      Surrogates

 4-Bromofl uorobenzene         174
 l,2-Dichlorobenzene-d4       150

      Target Analvtes

 Benzene                       78
 Bromobenzene                 156
 Bromochloromethane           128
 Bromodichloromethane         162
 Bromoform                    250
 Bromomethane                  94
 n-Butylbenzene               134
 sec-Butyl benzene             134
 tert-Butylbenzene            134
 Carbon tetrachloride         152
 Chlorobenzene                112
 Chloroethane                  64
 Chloroform                   118
 Chloromethane                 50
 2-Chlorotoluene              126
 4-Chlorotoluene              126
 Dibromochloromethane         206
 1,2-Dibromo-3-Chloropropane  234
 1,2-Dibromoethane            186
 Dibromomethane               172
 1,2-Dichlorobenzene          146
 1,3-Dichlorobenzene          146
 1,4-Dichlorobenzene          146
 Dichlorodifluoromethane      120
 1,1-Dichloroethane            98
 1,2-Dichloroethane            98
 1,1-Dichloroethene            96
 cis-l,2-Dichloroethene        96
trans-l,2-Dichloroethene      96
 1,2-Dichloropropane          112
 1,3-Dichloropropane          112
2,2-Dichloropropane          112
              96
              95
             152
              78
             156
             128
              83
             173
              94
              91
             105
             119
             117
             112
              64
              83
              50
              91
              91
             129
              75
             107
              93
             146
             146
             146
              85
              63
              62
              96
              96
              96
              63
              76
              77
                             77
                        174,176
                        115,150
                             77
                         77,158
                         49,130
                         85,127
                        175,252
                             96
                            134
                            134
                             91
                            119
                         77,114
                             66
                             85
                             52
                            126
                            126
                            127
                        155,157
                        109,188
                         95,174
                        111,148
                        111,148
                        111,148
                             87
                          65,83
                             98
                          61,63
                          61,98
                          61,98
                            112
                             78
                             97
                                     308

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1 , 1-Di chl oropropene
Compound
ci s-1 ,3-di chl oropropene
trans- 1 , 3-di chl oropropene
Ethyl benzene
Hexachl orobutadi ene
I sopropyl benzene
4- I sopropyl to! uene
Methyl ene chloride
Naphthalene
n-Propyl benzene
Styrene
1,1,1, 2-Tetrachl oroethane
1,1,2, 2-Tetrachl oroethane
Tetrachloroethene
Toluene
1,2, 3-Tri chl orobenzene
1,2, 4-Tri chl orobenzene
1,1, 1-Trichl oroethane
1,1, 2-Tri chl oroethane
Trichloroethene
Tri chl orof 1 uoromethane
1,2, 3-Tri chl oropropane
1,2, 4-Trimethyl benzene
1,3, 5-Tr imethyl benzene
Vinyl Chloride
o-Xylene
m-Xyl ene
p-Xylene
110
TABLE 1.
MWa
110
110
106
258
120
134
84
128
120
104
166
166
164
92
180
180
132
132
130
136
146
120
120
62
106
106
106
75
(continued)
Primary
Quantitation
Ion
75
75
91
225
105
119
84
128
91
104
131
83
166
92
180
180
97
83
95
101
75
105
105
62
106
106
106
110,77
Secondary
Quantitation
Ions
110
110
106
260
120
134,91
86,49

120
78
133,119
131,85
168,129
91
182
182
99,61
97,85
130,132
103
77
120
120
64
91
91
91
aMonoisotopic molecular weight  calculated  from  the  atomic masses  of  the
 isotopes with the smallest masses.
                                     309

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TABLE 2.
CHROMATOGRAPHIC RETENTION TIMES FOR METHOD ANALYTES
ON THREE COLUMNS WITH  FOUR SETS OF CONDITIONS0
                         Retention
                              Time      (min:sec)
Compound
Internal standard
Fluorobenzene
Surrogates
4-Bromof 1 uorobenzene
1 , 2-Di chl orobenzene-d4
Target Analvtes
Benzene
Bromobenzene
Bromochl oromethane
Bromodi chl oromethane
Bromoform
Bromomethane
n-Butyl benzene
sec-Butyl benzene
tert-Butyl benzene
Carbon Tetrachloride
Chlorobenzene
Chloroethane
Chl orof orm
Chl oromethane
2-Chlorotoluene
4-Chlorotoluene
Cyanogen chloride
Di bromochl oromethane
1 , 2-Di bromo-3-Chl oropropane
1,2-Dibromoethane
Dibromomethane
1 , 2-Di chl orobenzene
1,3-Dichlorobenzene
1 , 4-Di chl orobenzene
Di chl orodi f 1 uoromethane
1,1-Di chloroethane
1, 2-Di chloroethane
1,1-Dichloroethene
ci s-1 , 2-Di chl oroethene
trans-1 , 2-Di chl oroethene
1 , 2-Di chl oropropane
1 , 3-Di chl oropropane
2 , 2-Di chl oropropane
1 , 1-Di chl oropropene
Column lb

8:49

18:38
22:16

8:14
18:57
6:44
10:35
17:56
2:01
22:13
20:47
20:17
7:37
15:46
2:05
6:24
1:38
19:20
19:30

14:23
24:32
14:44
10:39
22:31
21:13
21:33
1:33
4:51
8:24
2:53
6:11
3:59
10:05
14:02
6:01
7:49
Column 2b

6:27

15:43
19:08

5:40
15:52
4:23
8:29
14:53
0:58
•19:29
18:05
17:34
5:16
13:01
1:01
4:48
0:44
16:25
16:43

11:51
21:05
11:50
7:56
19:10
18:08
18:23
0:42
2:56
5:50
1:34
3:54
2:22
7:40
11:19
3:48
5:17
Column 2V

14:06

23:38
27:25

13:30
24:00
12:22
15:48
22:46
4:48
27:32
26:08
25:36
13:10
20:40

12:36
3:24
24:32
24:46

19:12

19:24
15:26
27:26
26:22
26:36
3:08
10:48
13:38
7:50
11:56
9:54
15:12
18:42
11:52
13:06
Column 3d

8:03


• • .••",»•-•

7:25
16:25
5:38
9:20
15:42
1:17
17:57
17:28
17:19
7:25
14:20
1:27
5:33
0:58
16:44
16:49
1:03
12:48
18:02
13:36
9:05
17:47
17:28
17:38
0:53
4:02
7:00
2:20
5:04
3:32
8:56
12:29
5:19
7:10
                             310

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                             TABLE 2.   (continued)
Compound
                                 Retention
                    Time
(min:sec)
Column lb  Column 2b  Column  2b  Column 3d
ci s-1 , 3-di chl oropropene
trans-1 , 3-di chl oropropene
Ethyl benzene
Hexachl orobutadi ene
Isopropyl benzene
4- I sopropy 1 tol uene
Methyl ene Chloride
Naphthalene
n-Propyl benzene
Styrene
1,1,1, 2-Tetrachl oroethane
1,1,2, 2-Tetrachl oroethane
Tetrachl oroethene
Toluene
1 , 2 , 3-Tr i chl orobenzene
1,2, 4-Tri chl orobenzene
1,1, 1-Tri chl oroethane
1,1, 2-Tri chl oroethane
Tri chl oroethene
Tri chl orof 1 uoromethane
1,2, 3-Tri chl oropropane
1,2, 4-Tri methyl benzene
1,3, 5-Tr i methyl benzene
Vinyl chloride
o-Xyl ene
m-Xyl ene
p-Xylene
11.58
13.46
15:59
26:59
18:04
21:12
3:36
27:10
19:04
17:19
15:56
18:43
13:44
12:26
27:47
26:33
7:16
13:25
9:35
2:16
19:01
20:20
19:28
1:43
17:07
16:10
16:07


13:23
23:41
15:28
18:31
2:04
23:31
16:25
14:36
13:20
16:21
11:09
10:00
24:11
23:05
4:50
11:03
7:16
1:11
16:14
17:42
16:54
0:47
14:31
13:41
13:41
16:42
17:54
21:00
32:04
23:18
26:30
9:16
32:12
24:20
22:24
20:52
24:04
18:36
17:24
32:58
31:30
12:50
18:18
14:48
6:12
24:08
31:30
24:50
3:56
22:16
21:22
21:18


14:44
19:14
16:25
17:38
2:40
19:04
16:49
15:47
14:44
15:47
13:12
11:31
19:14
18:50
6:46
11:59
9:01
1:46
16:16
17:19
16:59
1:02
15:47
15:18
15:18
8Columns 1-3 are those given in Sect. 6.3.2.1; retention times were measured
 from the beginning of thermal desorption from the trap (columns 1-2) or from
 the beginning of thermal release from the cryogenic interface (column 3).
bdC conditions given in Sect. 11.3.1.
^GC conditions given in Sect. 11.3.2.
 GC conditions given in Sect. 11.3.3.
                                      311

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TABLE 3. ION ABUNDANCE CRITERIA FOR 4-BROHOFLUOROBENZENE (BFB)
   Mass
   (H/z)
    50
    75
    95
    96
   173
   174
   175
   176
   177
Relative Abundance Criteria
15 to 40% of mass 95
30 to 80% of mass 95
Base Peak, 100% Relative Abundance
5 to 9% of mass 95
< 2% of mass 174
> 50% of mass 95
5 to 9% of mass 174
> 95% but < 101% of mass 174
5 to 9% of mass 176
                               312

-------
TABLE 4.  ACCURACY AND PRECISION DATA FROM 16-31 DETERMINATIONS OF THE METHOD
          ANALYTES IN REAGENT WATER USING WIDE BORE CAPILLARY COLUMN la
Comoound
Benzene
Brotnobenzene
Bromochl oromethane
Bromodi chl oromethane
Bromoform
Bromomethane
n-Butyl benzene
sec-Butyl benzene
tert-Butyl benzene
Carbon tetrachloride
Chlorobenzene
Chloroethane
Chi orof orm
Chi oromethane
2-Chlorotoluene
4-Chlorotoluene
Di bromochl oromethane
1 , 2-Di bromo-3-chl oropropane
1,2-Dibromoethane
Dibromomethane
1 , 2-Di chl orobenzene
1 , 3-Di chl orobenzene
1 , 4-Di chl orobenzene
Di chl orodi f 1 uoromethane
1,1-Di chloroethane
1,2-Dichloroethane
1,1-Di chl oroethene
cis-1,2 Dichloroethene
trans-1 , 2-Di chl oroethene
1 , 2-Di chl oropropane
1 , 3-Di chl oropropane
2 , 2-Di chl oropropane
1 , 1-Di chl oropropene
ci s-1 , 2-Di chl oropropene
trans-1 , 2-Di chl oropropene
Ethyl benzene
Hexachl orobutadi ene
I sopropyl benzene
4-Isopropyl toluene
Methyl ene chloride
Naphthalene
n-Propyl benzene
Styrene
True
Cone.
Range
(uafl}
0.1-10
0.1-10
0.5-10
0.1-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.1-10
0.5-10
0.5-10
0.5-10
0.1-10
0.1-10
0.1-10
0.5-10
0.5-10
0.5-10
0.1-10
0.5-10
0.2-20
0.5-10
0.5-10
0.1-10
0.1-10
0.5-10
0.1-10
0.1-10
0.1-10
0.5-10
0.5-10


0.1-10
0.5-10
0.5-10
0.1-10
0.1-10
0.1-100
0.1-10
0.1-100
Mean
Accuracy
(% of True
Valued
97
100
90
95
101
95
100
100
102
84
98
89
90
93
90
99
92
83
102
100
93
99
103
90
96
95
94
101
93
97
96
86
98


99
100
101
99
95
104
100
102
Rel.
Std.
Dev.
m
5.7
5.5
6.4
6.1
6.3
8.2
7.6
7.6
7.3
8.8
5.9
9.0
6.1
8.9
6.2
8.3
7.0
19.9
3.9
5.6
6.2
6.9
6.4
7.7
5.3
5.4
6.7
6.7
5.6
6.1
6.0
16.9
8.9


8.6
6.8
7.6
6.7
5.3
8.2
5.8
7.2
Method
Det.
Limit
(UQ/l}
0.04
0.03
0.04
0.08
0.12
0.11
0.11
0.13
0.14
0.21
0.04
0.10
0.03
0.13
0.04
0.06
0.05
0.26
0.06
0.24
0.03
0.12
0.03
0.10
0.04
0.06
0.12
0.12
0.06
0.04
0.04
0.35
0.10


0.06
0.11
0.15
0.12
0.03
0.04
0.04
0.04
                                     313

-------
                             TABLE 4.  (Continued)
Compound
1,1,1, 2-Tetrachl oroethane
1,1,2, 2-Tetrachl oroethane
Tetrachl oroethene
To! uene
1,2,3-Trichlorobenzene
1,2, 4-Tr i chl orobenzene
1,1, 1-Tri chl oroethane
1,1, 2-Tri chl oroethane
Tri chl oroethene
Tri chl orof 1 uoromethane
1,2,3-Trichloropropane
1 , 2, 4-Trimethyl benzene
1,3, 5-Trimethyl benzene
Vinyl chloride
o-Xyl ene
m-Xyl ene
p-Xylene
True
Cone.
Range
rua/L)
0.5-10
0.1-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.5-10
0.1-31
0.1-10
0.5-10
Mean
Accuracy
(% of True
Value}
90
91
89
102
109
108
98
104
90
89
108
99
92
98
103
97
104
Rel.
Std.
Dev.
(%)
6.8
6.3
6.8
8.0
8.6
8.3
8.1
7.3
7.3
8.1
14.4
8.1
7.4
6.7
7.2
6.5
7.7
Method
Det.
Limit
(UQ/L)
0.05
0.04
0.14
0.11
0.03
0.04
0.08
0.10
0.19
0.08
0.32
0.13
0.05
0.17
0.11
0.05
0.13
"Data obtained by Robert W.  Slater using column 1  with a jet separator
 interface and a quadrupole mass spectrometer (Sect. 11.3.1) with analytes
 divided among three solutions.
                                      314

-------
TABLE 5.  ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF THE
          METHOD ANALYTES IN REAGENT WATER USING THE CRYOGENIC TRAPPING
          OPTION AND A NARROW BORE CAPILLARY COLUMN 3°
Compound
Benzene
Bromobenzene
Bromochl oromethane
Bromodi chl oromethane
Bromoform
Bromomethane
n-Butyl benzene
sec-Butylbenzene
tert-Butyl benzene
Carbon tetrachloride
Chl orobenzene
Chloroethane
Chloroform
Chl oromethane
2-Chlorotoluene
4-Chlorotoluene
Cyanogen chloride13
Di bromochl oromethane
1 , 2-Di bromo-3-chl oropropane
1,2-Dibromoethane
Dibromomethane
1 , 2-Di chl orobenzene
1 , 3-Di chl orobenzene
1 , 4-Di chl orobenzene
Di chl orodi f 1 uoromethane
1,1-Di chloroethane
1, 2-Di chloroethane
1,1-Di chl oroethene
cis-1, 2 Di chl oroethene
trans-1 , 2-Di chl oroethene
1 , 2-Di chl oropropane
1,3-Dichloropropane
2 , 2-Di chl oropropane
1 , 1-Di chl oropropene
cis-1, 3-Di chl oropropene
trans-1, 3-Di chl oropropene
Ethyl benzene
Hexachlorobutadiene
Isopropyl benzene
4-Isopropyl toluene
Methyl ene chloride
Naphthalene
True
Cone.
(UQ/L)
0.1
0.5
0.5
0.1
0.1
0.1
0.5
0.5
0.5
0.1
0.1
0.1
0.1
0.1
0.1
0.1

0.1
0,1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1


0.1
0.1
0.5
0.5
0.5
0.1
Mean
Accuracy
(% of True
Value}
99
97
97
100
99
99
94
90
90
92
91
100
95
99
99
96
92
99
92
97
93
97
99
93
99
98
100
95
100
98
96
99
99
98


99 ,
100
98
87
97
98
Rel.
Std.
Dev.
6.2
7.4
5.8
4.6
5.4
7.1
6.0
7.1
2.5
6.8
5.8
5.8
3.2
4.7
4.6
7.0
10.6
5.6
10.0
5.6
6.9
3.5
6.0
5.7
8.8
6.2
6.3
9.0
3.7
7.2
6.0
5.8
4.9
7.4


5.2
6.7
6.4
13.0
13.0
7.2
Method
Dect.
Limit
(ua/L)
0.03
0.11
0.07
0.03
0.20
0.06
0.03
0.12
0.33
0.08
0.03
0.02
0.02
0.05
0.05
0,05
0.30
0.07
0.05
0.02
0.03
0.05
0.05
0.04
0.11
0.03
0.02
0.05
0.06
0.03
0.02
0.04
0.05
0.02


0.03
0.04
0.10
0.26
0.09
0.04
                              315

-------
                             TABLE 5.  (Continued)
Compound
n-Propyl benzene
Styrene
1,1,1, 2-Tetrachl oroethane
1,1,2, 2-Tetrachl oroethane
Tetrachl oroethene
Toluene
1 , 2,3-Trichl orobenzene
1,2, 4-Tri chl orobenzene
1,1, 1-Tri chl oroethane
1,1, 2-Tri chl oroethane
Tri chl oroethene
Tri chl orof 1 uoromethane
1,2, 3-Tri chl oropropane
1,2, 4-Tri methyl benzene
1,3, 5-Tr i methyl benzene
Vinyl chloride
o-Xyl ene
m-Xyl ene
p-Xyl ene
True
Cone.
(U.Q/L)
0.1
0.1
0.1
0.5
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Mean
Accuracy
(% of True
Value}
99
96
100
100
96
100
98
91
100
98
96
97
96
96
99
96
94
94
97
Rel . Method
Std. Dect.
Dev. Limit
m (ua/U
6.6
19.0
4.7
12.0
5.0
5.9
8.9
16.0
4.0
4.9
2.0
4.6
6.5
6.5
4.2
0.2
7.5
4.6
6.1
0.06
0.06
0.04
0.20
0.05
0.08
0.04
0.20
0.04
0.03
0.02
0.07
0.03
0.04
0.02
0.04
0.06
0.03
0.06
8Data obtained by Caroline A.  Madding using  column  3 with  a  cryogenic
 interface and a quadrupole mass spectrometer (Sect 11.3.3).
Reference 8.
                                      316

-------
        TABLE 6. ACCURACY AND  PRECISION DATA  FROM SEVEN DETERMINATIONS
                 OF THE METHOD ANALYTES IN REAGENT WATER USING WIDE  BORE
                 CAPILLARY COLUMN 2a
Compound
Mean Accuracy
(% of True
Value,
No.b 2 ua/l Cone.}
RSD
M
Mean Accuracy
(% of True
Value,
0.2 ua/l Conc.^
RSD
'(*)
 Internal Standard
Fluorobenzene                 1

Surrogates

4-BromofI uorobenzene          2       98
l,2-Dichlorobenzene-d4       3       97

Target Analvtes

Benzene
Bromobenzene
Bromochloromethane
Bromodi chloromethane
Bromoform
Bromomethane
n-Butylbenzene
sec-Butyl benzene
tert-Butylbenzene
Carbon tetrachloride
Chlorobenzene
Chloroethane0
Chloroform
Chloromethane
2-Chlorotoluene
4-Chlorotoluene
Di bromochloromethane
1,2-Di bromo-3-chloropropanec
l,2-Dibromoethanec
Dibromomethane              13       99
1,2-Dichlorobenzene         45       93
1,3-Dichlorobenzene         46      100
1,4-Dichlorobenzene         47       98
Dichlorodifluoromethane     14       38
1,1-Dichloroethane          15       97
1,2-Dichloroethane          16      102
1,1-Dichloroethene          17       90
cis-l,2-Dichloroethene      18      100
trans-1,2-Dichloroethene    19       92
37
38
4
5
6
7
39
40
41
8
42
9
10
43
44
11
97
102
99
96
89
55
89
102
101
84
104
97
110
91
89
95
  1.8
 3.2
  4.4
  3.0
  5.2
  1.8
  2.4
 27.
.  4.8
  3.5
  4.5
  3.2
  3.1

  2.0
  5.0
  2.4
  2.0
  2.7
 2.1
 2.7
 4.0
 4.1
25.
 2.3
 3.8
 2.2
 3.4
 2.1
 96
 95
113
101
102
100
 90
 52
 87
100
100
 92
103

 95
 d
108
108
100
 95
 94
 87
 94
 d
 85
100
 87
 89
 85
 1.3
1.7
1.8
1.9
2.9
1.8
2.2
6.7
2.3
2.8
  9
2.6
1.6
2
2.1

3.1
4.4
3.0
2.2
5.1
2.3
2.8

3.6
2.1
3.8
2.9
2.3
                                     317

-------
                            TABLE  6.  (Continued)
Compound
1 , 2-Di chl oropropane
1,3-Dichloropropane
2 , 2-Di chl oropropane0
1 , 1-Di chl oropropene0
ci s-1 , 3-Di chl oropropene0
trans-1 , 3-Di chl oropropene
Ethyl benzene
Hexachl orobutadi ene
Isopropyl benzene
4-Isopropyl to! uene
Methyl ene chloride
Naphthalene
n-Propyl benzene
Styrene
1,1,1, 2-Tetrachl oroethane
1 , 1 , 2, 2-Tetrachl oroethane
Tetrachloroethene
To! uene
1,2, 3-Tr i chl orobenzene
1 , 2 , 4-Tri chl orobenzene
1,1, 1-Tri chl oroethane
1,1, 2-Tri chl oroethane
Trichloroethene
Tri chl orof 1 uoromethane
1,2, 3-Tr i chl oropropane
1,2, 4-Tri methyl benzene
1,3, 5-Trimethyl benzene
Vinyl chloride
o-Xyl ene
m-Xyl ene
p-Xyl ene
Mean Accuracy
(% of True
Value, RSD
No.b 2 ua/L Cone.1) (%)
20
21



25
48
26
49
50
27
51
52
53
28
29
30
54
55
56
31
32
33
34
35
57
58
36
59
60
61
102
92



96
96
91
103
95
e
93
102
95
99
101
97
105
90
92
94
107
99
81
97
93
88
104
97
f
98
2.2
3.7



1.7
9.1
5.3
3.2
3.6

7.6
4.9
4.4
2.7
4.6
4.5
2.8
5.7
5.2
3.9
3.4
2.9
4.6
3.9
3.1
2.4
3.5
1.8

2.3
Mean Accuracy
(% of True
Value, RSD
0.2 ua/L Cone.) M
103
93



99
ioo
88
101
95
e
78
97
104
95
84
92
126
78
83
94
109
106
48
91
106
97
115
98
f
103
2.9
3.2



2.1
4.0
2.4
2.1
3.1

8.3
2.1
3.1
3.8
3.6
3.3
1.7
2.9
5.9
2.5
2.8
2.5
13.
2.8
2.2
3.2
14.
1.7

1.4
8Data obtained by James W.  Eichelberger using column  2 with  the open  split
 interface and an ion trap mass spectrometer (Sect. 11.3.2)  with all  method
 analytes in the same reagent water solution.
Designation in Figures 1 and 2.
°Not measured; authentic standards were not available.
dNot found at 0.2 ng/l.
cNot measured; methylene chloride was in the laboratory reagent blank.
fm-xylene coelutes with and cannot be distinguished from its isomer p-xylene,
 No 61.
                                      318

-------
   OPTIONAL
   FOAM
   TRAP
KIN.
0. D. EXIT
    0.0.

 14MM 0. D.
                  INLET* IN.
                       0.0.
   SAMPLE INLET

i~*~24IAY SYRINGE VALVE
   17CM. 20 GAUGE SYRINGE NEEDLE

   GMM. 0. 0. RUBBER SffTUM
                        ~10MM. 0. D.
                           % IN. 0. D.
                    1/16 IN. O.D.
                    'STAINLESS STEEL
   10MM GLASS FRIT
   MEDIUM POROSITY
                                       131 MOLECULAR
                                       SIEVE PURGE
                                       GASnLTER
                                         PURGE GAS
                                         ROW
                                         CONTROL
             FIGURE 1.  PURGING DEVICE
                        319

-------
    PACKING PROCEDURE
CONSTRUCTION
     GLASS em
     WOOL  ***
ACTIVATED, „
CHARCOAL.7J
GRADE 15
SIUCA
   TENAX 7.7 CM
3XOV-1
GLASS WOOL1
        5MM
                     7A/FOOT
                   RESISTANCE
                  WIRE WRAPPED
                     SOLID
                (DOUBLE LAYER)
                   RESISTANCE
                  •IRE WRAPPED
                        SOLID
                 (SINGLE LAYER)
                         8OH
            TRAP INLET
   JC)
         .COMPRESSION
          RHING NUT
          AND FERRULES


           THERMOCOUPLE/
           CONTROLLER
           SENSOR
              B£CTRONIC
              fEMPERATURE
              CONTROL
              AND
              PYROMETER
       ^  / TUBING 2SCU
           0.105 IN. I.D,
       ;> J 0.12S IN. O.D.
       ,X  STAINLESS STEa
    FIGURE 2.  TRAP PACKINGS AND CONSTRUCTION TO INCLUDE
               DESORB CAPABILITY
                        320

-------
o o
                                                                                 CVS
                                                                                 CNS
O
M
                                           321

-------
  w
                                                                        cxa
                                                                        SJO
                                                                        CSI
                                                                        CO
                                                                        CK3
o
                                           322

-------
METHOD 525.1  DETERMINATION OF ORGANIC COMPOUNDS IN DRINKING WATER
        BY LIQUID-SOLID EXTRACTION AND CAPILLARY COLUMN
              GAS CHROMATOGRAPHY/MASS SPECTROMETRY
                           Revision 2.2
                             May,  1991
J. W. Eichelberger, T. D. Behymer, W. L. Budde - Method 525,
  Revision 1.0, 2.0, 2.1 (1988)
           ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
                OFFICE OF RESEARCH AND DEVELOPMENT
               U.S.  ENVIRONMENTAL PROTECTION AGENCY
                      CINCINNATI, OHIO 45268
                               323

-------
                                 METHOD 525.1

             DETERMINATION OF ORGANIC COMPOUNDS IN DRINKING WATER
               BY LIQUID-SOLID EXTRACTION AND CAPILLARY COLUMN
                     GAS CHROMATOGRAPHY/MASS SPECTROMETRY
1.   SCOPE AND APPLICATION

     1.1   This is a general purpose method that provides procedures for
           determination of organic compounds in finished drinking water, raw
           source water, or drinking water in any treatment stage.  The method
           is applicable to a wide range of organic compounds that are
           efficiently partitioned from the water sample onto a C18 organic
           phase chemically bonded to a solid silica matrix in a cartridge or
           disk, and sufficiently volatile and thermally stable for gas
           chromatography.  Single-laboratory accuracy and precision data have
           been determined at two concentrations with two instrument systems
           for the following compounds:
          Compound

     Acenaphthylene
     Alachlor
     Aldrin
     Anthracene
     Atrazine
     Benz[a]anthracene
     Benzo[b]f1uoranthene
     Benzo[k]f1uoranthene
     Benzo[a]pyrene
     Benzo[g,h,i]perylene
     Butyl benzylphthalate
     Chlordane components
       Alpha-chlordane
       Gamma-chlordane
       Trans nonachlor
     2-Chlorobiphenyl
     Chrysene
     Dibenz[a,h]anthracene
     Di-n-butylphthalate
     2,3-Dichlorobiphenyl
     Diethylphthalate
     Bis(2-ethylhexyl)adipate
     Bi s(2-ethylhexyl)phthalate
     Dimethylphthalate
     Endrin
     Fluorene
     Heptachlor
MW1

152
269
362
178
215
228
252
252
252
276
312

406
406
440
188
228
278
278
222
222
222
390
194
378
166
370

324
Chemical Abstracts Service
	Registry Number	
          208
         15972
          309
          120
          1912
            56
          205
          207
            50
          191-
            85-

          5103-
          5103-
         39765-
          2051-
          218-
            53-
            84-
         16605-
            84-
          103-
          117-
          131-
            72-
            86-
            76-
•96-8
-60-8
-00-2
-12-7
•24-9
-55-3
-82-3
•08-9
-32-8
-24-2
-68-7

-71-9
-74-2
-80-5
-60-7
-01-9
-70-3
-72-2
-91-7
-66-2
-23-1
-81-7
-11-3
-20-8
 73-7
 44-8

-------

Compound
Heptachlor epoxide
2,2',3,3',4,4I,6-Heptachloro-
bi phenyl
Hexachlorobenzene
2,2',4,4',5,6'-Hexachloro-
bi phenyl
Hexachl orocycl opentadi ene
Indeno[l,2,3,c,d]pyrene
Lindane
,, Methoxychlor
2,2', 3,3', 4,5', 6,6' -Qcta-
chlorobi phenyl
2,2',3',4,6-Pentachloro-
biphenyl
Pentachlorophenol
Phenanthrene
. Pyrene
Simazine
2 , 2 ' , 4 , 4 ' -Tetrachl orobi phenyl
Toxaphene mixture
2, 4, 5-Trichl orobi phenyl

MW1
386

392
282

358
270
276
288
344

426

324
264
178
202
201
290

256
Chemical Abstracts Service
Reaistrv Number
1024-57-3

52663-71-5
118-74-1

60145-22-4
77-47-4
193-39-5
58-89-9 :
72-43-5

40186-71-8

60233-25-2
87-86-5
85-01-8
129-00-0
122-34-9
2437-79-8
8001-35-2
15862-07-4
     1.2
 Monoisotopic molecular weight calculated from the atomic masses of
the isotopes with the smallest masses.

A laboratory may use this method to identify and measure additional
analytes after the laboratory obtains acceptable (defined in Sect.
10) accuracy and precision data for each added analyte.

Method detection limit (MDL) is defined as the statistically calcu-
lated minimum amount that can be measured with 99% confidence that
the reported value is greater than zero (1).,  The MDL is compound
dependent and is particularly dependent on extraction efficiency
and sample matrix.  For the listed analytes, MDLs vary from 0.01 to
15 fig/I.  The concentration calibration range of this method is
0.1 /ig/L to 10
2.   SUMMARY OF METHOD

     Organic compound analytes, internal  standards, and surrogates are
     extracted from a water sample by passing 1 liter of sample water through
     a cartridge or disk containing a solid inorganic matrix coated with a
     chemically bonded C18 organic phase (liquid-solid extraction,  LSE).  The
     organic compounds are eluted from the LSE cartridge or disk with a small
     quantity of methyl ene chloride,  and  concentrated further by evaporation
     of some of the solvent.   The sample  components are separated, identified,
     and measured by injecting an aliquot  of the concentrated methyl ene

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     chloride extract into a high resolution fused silica capillary column of
     a gas chromatography/mass spectrometry (GC/MS) system.  Compounds eluting
     from the GC column are identified by comparing their measured mass
     spectra and retention times to reference spectra and retention times in a
     data base.  Reference spectra and retention times for analytes are
     obtained by the measurement of calibration standards under the same
     conditions used for samples.  The concentration of each identified
     component is measured by relating the MS response of the quantitation ion
     produced by that compound to the MS response of the quantitation ion
     produced by a compound that is used as an internal standard.  Surrogate
     analytes, whose concentrations are known in every sample, are measured
     with the same internal standard calibration procedure.

3.   DEFINITIONS

     3.1   Internal standard — A pure analyte(s) added to a solution in known
           amount(s) and used to measure the relative responses of other
           method analytes and surrogates that are components of the same
           solution.  The internal standard must be an analyte that is not a
           sample component.

     3.2   Surrogate analyte — A pure analyte(s), which is extremely unlikely
           to be found in any sample, and which is added to a sample aliquot
           in known amount(s) before extraction and is measured with the same
           procedures used to measure other sample components.  The purpose of
           a surrogate analyte is to monitor method performance with each
           sample.

     3.3   Laboratory duplicates (LD1 and LD2) — Two sample aliquots taken in
           the analytical laboratory and analyzed separately with identical
           procedures.  Analyses of LD1 and LD2 give a measure of the
           precision associated with laboratory procedures, but not with
           sample collection, preservation, or storage procedures.

     3.4   Field duplicates (FD1 and FD2) — Two separate samples collected at
           the same time and place under identical circumstances and treated
           exactly the same throughout field and laboratory procedures.
           Analyses of FD1 and FD2 give a measure of the precision associated
           with sample collection, preservation, and storage, as well as with
           laboratory procedures.

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

     3.6   Field reagent blank (FRB) -- Reagent water placed in a sample
           container in the laboratory and treated as a sample in all
           respects, including exposure to sampling site conditions, storage,
           preservation, and all analytical procedures.  The purpose of the

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      FRB is to determine if method analytes or other interferences are
      present in the field environment.

3.7   Laboratory performance check solution (LPC) — A solution of method
      analytes, surrogate compounds, and internal standards used to
      evaluate the performance of the instrument system with respect to a
      defined set of method criteria.

3.8   Laboratory fortified blank (LFB) ~ An aliquot of reagent water to
      which known quantities of the method analytes are added in the
      laboratory.  The LFB is analyzed exactly like a sample, and its
      purpose is to determine whether the methodology is in control, and
      whether the laboratory is capable of making accurate and precise
      measurements at the required method detection limit.

3.9   Laboratory fortified sample matrix (LFM) — An aliquot of an
      environmental sample to which known quantities of the method
      analytes are added in the laboratory.  The LFM is analyzed exactly
      like a sample, and its purpose is to determine whether the sample
      matrix contributes bias to the analytical results.  The background
      concentrations of the analytes in the sample matrix must be
      determined in a separate aliquot and the measured values in the LFM
      corrected for background concentrations.

3.10  Stock standard solution — A concentrated solution containing a
      single certified standard that is a method analyte,, or a
      concentrated solution of a single analyte prepared in the
      laboratory with an assayed reference compound.  Stock standard
      solutions are used to prepare primary dilution standards.

3.11  Primary dilution standard solution — A solution of several
      analytes prepared in the laboratory from stock standard solutions
      and diluted as needed to prepare calibration solutions and other
      needed analyte solutions.

3.12  Calibration standard (CAL) — a solution prepared from the primary
      dilution standard solution and stock standard solutions of the
      internal standards and surrogate analytes.  The CAL solutions are
      used to calibrate the instrument response with respect to analyte
      concentration.

3.13  Qual.ity control sample (QCS) — a sample matrix containing method
      analytes or a solution of method analytes in a water miscible
      solvent which is used to fortify reagent water or environmental
      samples.  The QCS is obtained from a source external to the
      laboratory, and is used to check laboratory performance with
      externally prepared test materials.
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4.   INTERFERENCES

     4.1   During analysis, major contaminant sources are reagents and liquid-
           solid extraction columns.  Analyses of field and laboratory reagent
           blanks provide information about the presence of contaminants.

     4.2   Interfering contamination may occur when a sample containing low
           concentrations of compounds is analyzed immediately after a sample
           containing relatively high concentrations of compounds.  Syringes
           and splitless injection port liners must be cleaned carefully or
           replaced as needed.  After analysis of a sample containing high
           concentrations of compounds, a laboratory reagent blank should be
           analyzed to ensure that accurate values are obtained for the next
           sample.

5.   SAFETY

     5.1   The toxicity or carcinogen!city of chemicals used in this method
           has not been precisely defined; each chemical should be treated as
           a potential health hazard, and exposure to these chemicals should
           be minimized.  Each laboratory is responsible for maintaining
           awareness of OSHA regulations regarding safe handling of chemicals
           used in this method.  Additional references to laboratory safety
           are cited (2-4).

     5.2   Some method analytes have been tentatively classified as known or
           suspected human or mammalian carcinogens.  Pure standard materials
           and stock standard solutions of these compounds should be handled
           with suitable protection to skin, eyes, etc.

6.   Apparatus and Equipment

     6.1   All glassware must be meticulously cleaned.  This may be
           accomplished by washing with detergent and water, rinsing with
           water, distilled water, or solvents, air-drying, and heating (where
           appropriate) in an oven.  Volumetric glassware is never heated.

     6.2   Sample containers.  1-liter or 1-quart amber glass bottles fitted
           with a Teflon-lined screw cap.  (Bottles in which high purity
           solvents were received can be used as sample containers without
           additional  cleaning if they have been handled carefully to avoid
           contamination during use and after use of original contents.)

     6.3   Separatory funnels.  2-liter and 100-mL with a Teflon stopcock.

     6.4   Liquid chromatography column reservoirs.  Pear-shaped 100- or 125-
           mL vessels without a stopcock but with a ground glass outlet joint
           sized to fit the liquid-solid extraction column.  (Lab Glass, Inc.
           part no. ML-700-706S, with a 24/40 top outer joint and a 14/35
           bottom inner joint, or equivalent).  A 14/35 outlet joint fits some
           commercial  cartridges.
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6.5   Syringe needles. No. 18 or 20 stainless steel.

6.6   Vacuum flasks.  1- or 2-liter with solid 'rubber stoppers.

6.7   Volumetric flasks, various sizes.

6.8   Laboratory or aspirator vacuum system.  Sufficient capacity to
      maintain a slight vacuum of 13 cm (5 in.) of mercury in the vacuum
      flask.

6.9   Micro syringes, various sizes.

6.10  Vials.  Various sizes of amber vials with Teflon-lined screw caps.

6.11  Drying column.  Approximately 1.2 cm x 40 cm with 10 mL graduated
      collection vial.

6.12  Analytical balance.  Capable of weighing 0.0001 g accurately.

6.13  Fused silica capillary gas chromatography column.  Any capillary
      column that provides adequate resolution, capacity, accuracy, and
      precision (Sect. 10) can be used.  A 30 m X 0.25 mm id fused silica
      capillary column coated with a 0.25 urn bonded film of polyphenyl-
      methylsilicone  is recommended (J&W DB-5 or equivalent).

6.14  Gas chromatograph/mass spectrometer/data system (GC/MS/DS)

      6.14.1  The GC  must be capable of temperature programming and be
              equipped for split!ess/split or on-column capillary
              injection.  The injection tube liner should be quartz and
              about 3 mm  in diameter.  The injection system must not
              allow the analytes to contact hot stainless steel or other
              metal surfaces that promote decomposition.

      6.14.2  The GC/MS interface should allow the capillary column or
              transfer line exit to be placed within a few mm of the ion
              source.  Other interfaces, for example the open split
              interface,  are acceptable as long as the system has
              adequate sensitivity  (see Sect. 9 for calibration
              requirements).

      6.14.3  The mass spectrometer must be capable of electron
              ionization  at a nominal electron energy of 70 eV.  The
              spectrometer must be capable of scanning from 45 to 450 amu
              with a  complete scan cycle time (including scan overhead)
              of 1.5  sec  or less.   (Scan cycle time = Total MS data
              acquisition time in sec divided by number of scans in the
              chromatogram).  The spectrometer must produce a mass
              spectrum that meets all criteria in Table 1 when 5 ng or
              less of DFTPP is introduced into the GC.  An average
              spectrum across the DFTPP GC peak may be used to test
              instrument  performance.

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     6.15
6.14.4  An interfaced data system is required to acquire, store,
        reduce, and output mass spectral data.  The computer
        software must have the capability of processing stored
        GC/MS data by recognizing a GC peak within any given
        retention time window, comparing the mass spectra from the
        GC peak with spectral data in a user-created data base, and
        generating a list of tentatively identified compounds with
        their retention times and scan numbers.  The software must
        also allow integration of the ion abundance of an/specific
        ion between specified time or scan number limits,
        calculation of response factors as defined in Sect. 9.2.6
        (or construction of a second or third order regression
        calibration curve), calculation of response factor  .
        statistics (mean and standard deviation), and calculation
        of concentrations of analytes using either the calibration
        curve or the equation in Sect. 12.

Millipore Standard Filter Apparatus,  ALL GLASS. This will be used
if the disks are to be used to carry out the extraction instead of
the cartridges.
7.   REAGENTS AND CONSUMABLE MATERIALS

     7.1   Helium carrier gas, as contaminant free as possible.

     7.2   Liquid-solid extraction (LSE) cartridges.   Cartridges are inert
           non- leaching plastic, for example polypropylene,  or glass,  and
           must not contain plasticizers, such as phthalate esters or
           adipates, that leach into methylene chloride.   The cartridges are
           packed with about 1 gram of silica, or other inert inorganic
           support, whose surface is modified by chemically bonded octadecyl
           (cis) groups.  The packing must  have a narrow size distribution and
           must not leach organic compounds into methylene chloride.  One
           liter of water should pass through the cartridge in about 2  hrs
           with the assistance of a slight vacuum of  about 13 cm (5 in.) of
           mercury.  Sect.  10 provides criteria for acceptable LSE cartridges
           which are available from several commercial  suppliers.

           The extraction disks contain approximately 0.5  grams of 8 urn
           octadecyl bonded silica uniformly enmeshed in a matrix  of inert
           PFTE fibrils.   The size of the disks is  47mm x  0.5mm.   As with
           cartridges, the disks should not contain any organic compounds,
           either from the PFTE or the bonded silica,  which will leach  into
           the methylene  chloride eluant.  One liter  of reagent water should
           pass through the disks in 5-20 minutes using a  vacuum of about 66cm
           (26 in.) of mercury.   Section 10 provides  criteria for  acceptable
           LSE disks which  are available commercially.
     7.3    Solvents
           7.3.1    Methylene  chloride,  acetone,  toluene  and methanol
                   purity pesticide  quality  or equivalent.

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      7.3.2   Reagent water.  Water in which an interferent is not
              observed at the method detection limit of the compound of
              interest.  Prepare reagent water by passing tap water
              through a filter bed containing about 0.5 kg of activated
              carbon or by using a water purification system.  Store in
              clean, narrow-mouth bottles with Teflon-lined septa and
              screw caps.

7.4   Hydrochloric acid. 6N.

7.5   Sodium sulfate, anhydrous.  (Soxhlet extracted with methylene
      chloride for a minimum of 4 hrs.)

7.6   Stock standard solutions.  Individual solutions of analytes, surro-
      gates, and internal standards may be purchased as certified
      solutions or prepared from pure materials.  To prepare, add 10 mg
      (weighed on an analytical balance to 0.1 mg) of the pure material
      to 1.9 mi. of methanol or acetone in a 2-mL .volumetric flask, dilute
      to the mark, and transfer the solution to an amber glass vial.  If
      the analytical standard is available only in quantities smaller
      than 10 mg, reduce the volume of solvent accordingly.  Some
      polycyclic aromatic hydrocarbons are not soluble in methanol or
      acetone, and their stock standard solutions are prepared in
      toluene.  Methylene chloride should be avoided as a solvent for
      standards because its high vapor pressure leads to rapid
      evaporation and concentration changes.  Methanol and acetone are
      not as volatile as methylene chloride, but their solutions must
      also be handled with care to avoid evaporation.  Compounds 10, 11,
      and 35 in Table 2 are soluble in acetone.  Compounds 12, 13, and 20
      in Table 2 are soluble in toluene.  If compound purity is certified
      by the supplier at >96%, the weighed amount can be used without
      correction to calculate the concentration of the solution
      (5 /ig//iL).  Store the amber vials in a dark cool place.

7.7   Primary dilution standard solution.  The stock standard solutions
      are used to prepare a primary dilution standard.solution that
      contains multiple analytes.  The recommended solvent for this
      dilution is acetone.  Aliquots of each of the stock standard
      solutions are combined to produce the primary dilution in which the
      concentration of the analytes is at least equal to the
      concentration of the most concentrated calibration solution, that
      is, 10 ng//iL.  Store the primary dilution standard solution in an
      amber vial in a dark cool place, and check frequently for signs of
      deterioration or evaporation,  especially just before preparing
      calibration solutions.

7.8   Fortification solution of internal standards and surrogates.
      Prepare a solution of acenaphthene-D10, phenanthrene-D10,
      chrysene-Dt2, and perylene-D12, in methanol  or acetone at a
      concentration of 500 /jg/mL of each.  This solution is used in the
      preparation of the calibration solutions.   Dilute a portion of this
      solution by 10 to 50 /zg/mL and use this solution to fortify the

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     7.9
actual water samples (see Sect. 11.2).  Other surrogates, for
example, caffeine-  N2 and pyrene-D1Q may be included in this
solution as needed  (a 100-/zl_ aliquot of this 50 fig/ml solution
added to 1 liter of water gives a concentration of 5 /zg/L of each
internal standard or surrogate).  Store this solution in an amber
vial in a dark cool place.

MS performance check solution.  Prepare a 5 ng//iL solution of DFTPP
in methylene chloride.  Store this solution in an amber vial in a
dark cool place.
     7.10  Calibration solutions (CAL1 through CAL6).  Prepare a series of six
           concentration calibration solutions in acetone which contain all
           analytes except pentachlorophenol and toxaphene at concentrations
           of 10, 5, 2, 1, 0.5, and 0.1 ng//*L, with a constant concentration
           of 5 ng/nl of each internal standard and surrogate in each CAL
           solution. CAL1 through CAL6 are prepared by combining appropriate
           aliquots of the primary dilution standard solution (7.7) and the
           fortification solution (500 /zg/mL) of internal standards and
           surrogates (7.8). Pentachlorophenol is included in this solution at
           a concentration four times the other analytes.  Toxaphene CAL
           solutions should be prepared as separate solutions at
           concentrations of 250, 200, 100, 50, 25, and 10 ng//zL.  Store these
           solutions in amber vials in a dark cool place.  Check these
           solutions regularly for signs of deterioration, for example, the
           appearance of anthraquinone from the oxidation of anthracene.

     7.11  Reducing agents.  Sodium sulfite or sodium arsenite.  Sodium thio-
           sulfate is not recommended as it may produce a residue of elemental
           sulfur that can interfere with some analytes.

     7.12  Fortification solution for optional recovery standard.  Prepare a
           solution of terphenyl-D14  in methylene  chloride at  a  concentration
           of 500 fig/ml.  An aliquot of this solution may be added (optional)
           to the extract of the LSE cartridge to check on the recovery of the
           internal standards in the extraction process.

8.   SAMPLE COLLECTION. PRESERVATION. AND HANDLING

     8.1   Sample collection.  When sampling from a water tap, open the tap
           and allow the system to flush until the water temperature has
           stabilized (usually about 2-5 min).  Adjust the flow to about 500
           mL/min and collect samples from the flowing stream.  Keep samples
           sealed from collection time until analysis.  When sampling from an
           open body of water, fill the sample container with water from a
           representative area.  Sampling equipment, including automatic
           samplers, must be free of plastic tubing, gaskets, and other parts
           that may leach analytes into water.  Automatic samplers that
           composite samples over time must use refrigerated glass sample
           containers.
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     8.2   Sample dechlorination and preservation.   All  samples should be iced
           or refrigerated at 4°C  from  the  time  of  collection  until
           extraction.  Residual chlorine should be reduced at the sampling
           site by addition of a reducing agent. Add 40-50 mg of sodium
           sulfite or sodium arsehite (these may be added as solids with
           stirring until  dissolved) to each liter  of water.  Hydrochloric
           acid should be used at the sampling site to retard the
           microbiological degradation  of some analytes  in unchlorinated
           water.  The sample pH is adjusted to <2  with  6 N hydrochloric acid.
           This is the same pH used in  the extraction, and is required to
           support the recovery of pentachlorophenol.

     8.3   Holding time.  Samples must  be extracted within 7 days and the
           extracts analyzed within 30  days of sample collection.

     8.4   Field blanks.

           8.4.1   Processing of a field reagent blank (FRB) is recommended
                   along with each sample set, which is  composed of the
                   samples collected from the same  general sample site at
                   approximately the same time.   At the  laboratory, fill a
                   sample container with reagent water,  seal,  and ship to the
                   sampling site along  with the empty sample containers.
                   Return the FRB to the laboratory with filled sample
                   bottles.

           8.4.2   When hydrochloric acid is added  to samples, use the same
                   procedures to add the same amount to  the FRB.

9.   CALIBRATION

     9.1   Demonstration and documentation of acceptable initial calibration
           is required before any samples are analyzed and is required
           intermittently throughout sample analysis as  dictated by results of
           continuing calibration checks.  After initial calibration is
           successful, a continuing calibration check is required at the
           beginning of each 8 hr. period during which analyses are performed.
           Additional periodic calibration checks are good laboratory
           practice.

     9.2   INITIAL CALIBRATION

           9.2.1   Calibrate the mass and abundance scales of the MS with
                   calibration compounds and procedures  prescribed by the
                   manufacturer with any modifications necessary to meet the
                   requirements in Sect. 9.2.2.

           9.2.2   Inject into the GC a 1-/JL aliquot of the 5 ng/#L DFTPP
                   solution and acquire a mass spectrum that includes data for
                   m/z 45-450.  Use GC conditions that produce a narrow (at
                   least five scans per peak) symmetrical peak.  If the
                   spectrum does not meet all criteria (Table 1), the MS must
                   be retuned and adjusted to meet  all criteria before
                   proceeding with calibration.  An average spectrum across
                   the GC peak may be used to evaluate the performance of the
                   system.

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9.2.3   Inject a 1-/JL aliquot of a medium concentration calibration
        solution, for example 0.5-2 pg/L, and acquire and store
        data from m/z 45-450 with a total cycle time (including
        scan overhead time) of 1.5 sec or less.  Cycle time should
        be adjusted to measure at least five or more spectra during
        the elution of each GC peak.

        9.2.3.1  Multi-ramp temperature program GC conditions.
                 Adjust the helium carrier gas flow rate to about
                 33 cm/sec.  Inject at 45°C and hold in split!ess
                 mode for 1 min.  Heat rapidly to 130°C.   At 3 min
                 start the temperature program: 130-180°C at
                 12°/min;  180-240°C  at  7°/min; 240-320°C at 12°/min.
                 Start data acquisition at 5 min.

        9.2.3.2  Single ramp linear temperature program.  Adjust
                 the helium carrier gas flow rate to about 33
                 cm/sec.  Inject at 40°C and hold in splitless mode
                 for 1 min.  Heat rapidly to 160°C.   At 3 min start
                 the temperature program:  160-320°C at 6°/nrin;
                 hold at 320° for 2  min.  Start data acquisition at
                 3 min.

9.2.4   Performance criteria for the medium calibration.  Examine
        the stored GC/MS data with the data system software.
        Figure 1 shows an acceptable total ion chromatogram.

        9.2.4.1  GC performance.  Anthracene and phenanthrene
                 should be separated by baseline.
                 Benzfa]anthracene and chrysene should be separated
                 by a valley whose height is less than 25% of the
                 average peak height of these two compounds.  If
                 the valley between benz[a]anthracene and chrysene
                 exceeds 25%, the GC column requires maintenance.
                 See Sect. 9.3.6.

        9.2.4.2  MS sensitivity.  The GC/MS/DS peak identification
                 software should be able to recognize a GC peak in
                 the appropriate retention time window for each of
                 the compounds in calibration solution, and make
                 correct tentative identifications.   If fewer than
                 99% of the compounds are recognized, system
                 maintenance is required.  See Sect. 9.3.6.

        9.2.4.3  Lack of degradation of endrin.  Examine a plot of
                 the abundance of m/z 67 in the region of 1.05-1.3
                 of the retention time of endrin.  This is the
                 region of elution of endrin aldehyde, a product of
                 the thermal isomerization of endrin.  Confirm that
                 the abundance of m/z 67 at the retention time of
                 endrin aldehyde is <10% of the abundance of m/z 67
                 produced by endrin.  If more than 10% endrin
                 aldehyde is observed,  system maintenance is
                 required to correct the problem.  See Sect. 9.3.6.
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   9.2*5   If all performance criteria are met, inject a 1-/JL aliquot
           of each of the other CAL solutions using the same GC/MS
           conditions.

   9.2.6   Calculate a response factor (RF) for each analyte and
           surrogate for each CAL solution using the internal standard
           whose retention time is nearest the retention time of the
           analyte or surrogate.  Table 2 contains suggested internal
           standards for each analyte and surrogate, and quantitation
           ions for all compounds.  This calculation is supported in
           acceptable GC/MS data system software (Sect. 6.14.4), and
           many other software programs.  RF is a unit!ess number, but
           units used to express quantities of analyte and internal
           standard must be equivalent.
                                (Ax)(Qis)
                       RF =   	
                                (A1s)(Qx)

           where:
                        Ax =    integrated abundance of the
                                 quantitation ion of the analyte.
                        Ais =?   integrated abundance of the
                                 quantitation ion internal standard.
                        Qx  =   quantity of analyte injected in ng or
                                 concentration units.
                        Qjs .= .   quantity of internal standard injected
                                 in ng or concentration units.

              9.2.6.1   For  each analyte and surrogate, calculate the
                        mean RF from the analyses of the six CAL
                        solutions.   Calculate the standard deviation
                        (SD) and the relative standard deviation (RSD)
                        from each mean: RSD = 100 (SD/M).   If the RSD
                        of any analyte or surrogate mean RF exceeds
                        30%, either analyze additional aliquots of
                        appropriate CAL solutions to obtain an
                        acceptable RSD of RFs over the entire
                        concentration range, or take action to improve
                        GC/MS  performance.  See Sect. 9.2.7.

      9.2.7   As an alternative to  calculating mean  response  factors
              and applying the RSD  test,  use the GC/MS data system
              software  or other available software to  generate  a
              linear, second, or third order regression calibration
              curve.

9.3   Continuing calibration check.  Verify the MS tune and initial
      calibration at the beginning of each 8 hr. work  shift during
      which analyses are performed using the following procedure.

      9.3.1   Inject a  l-fil aliquot of the 5ng//zL  DFTPP solution and
              acquire a mass  spectrum that includes  data  for  m/z
              45-450.   If the spectrum does  not meet all  criteria

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         (Table 1),  the MS must be retuned and adjusted to meet
         all  criteria before proceeding with the continuing
         calibration check.

9.3.2    Inject a l-/iL aliquot of a medium concentration
         calibration solution and analyze with the same
         conditions  used during the initial  calibration.

9.3.3    Demonstrate acceptable performance for the criteria
         shown in Sect.  9.2.4.

9.3.4    Determine that the absolute areas of the quantitation
         ions of the internal  standards and surrogate(s) have not
         decreased by more than 30% from the areas measured in
         the  most recent continuing calibration check,  or by more
         than 50% from the areas measured during initial
         calibration.   If these areas have decreased by more than
         these amounts,  adjustments must be made to restore
         system sensitivity.   These adjustments may require
         cleaning of the MS ion source,  or other maintenance as
         indicated in Sect.  9.3.6,  and recalibration.   Control
         charts are  useful  aids in  documenting system sensitivity
         changes.

9.3.5    Calculate the RF for  each  analyte and surrogate from the
         data measured in the  continuing calibration check.  The
         RF for each analyte  and surrogate must be within 30% of
         the  mean  value  measured in the  initial  calibration.
         Alternatively,  if a  second or third order regression is
         used,  the point from  the continuing calibration check
         for  each  analyte and  surrogate  must fall,  within the
         analyst's judgement,  on the curve from the initial
         calibration.   If these conditions do not  exist,  remedial
         action must be  taken  which may  require reinitial
         calibration.

9.3.6    Some possible remedial  actions.   Major maintenance  such
         as cleaning an  ion source,  cleaning quadrupole  rods,
         etc.  require  returning to  the initial  calibration  step.

         9.3.6.1   Check and adjust GC and/or MS operating
                  conditions; check the MS resolution, and
                  calibrate the mass scale.

         9.3.6.2   Clean or replace the splitless injection
                  liner; silanize a new injection liner.

         9.3.6.3   Flush the GC column with solvent according to
                  manufacturer's instructions.

         9.3.6.4   Break off a short portion (about 1 meter) of
                  the column from the end near the injector; or
                  replace GC column.  This action will  cause a
                  change in retention times.
                        336

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                     9.3.6.5   Prepare fresh CAL solutions, and repeat the
                               initial  calibration step.

                     9.3.6.6   Clean the MS ion source and rods (if a
                               quadrupole).

                     9.3.6.7   Replace any components that allow analytes to
                               come into contact with hot metal surfaces.

                     9.3.6.8   Replace the MS electron multiplier, or any
                               other faulty components.

10.     QUALITY CONTROL

       10.1  Quality control (QC) requirements are the initial demonstration
             of laboratory capability followed by regular analyses of
             laboratory reagent blanks, laboratory fortified blanks, and
             laboratory fortified matrix samples.  The laboratory must
             maintain records to document the quality of the data generated.
             Additional quality control practices are recommended.

       10.2  Initial demonstration of low system background and acceptable
             particle size and packing.  Before any samples are analyzed, or
             any time a new supply of cartridges or disks is received from a
             supplier, it must be demonstrated that a laboratory reagent
             blank (LRB) is reasonably free of contamination that would
             prevent the determination of any analyte of concern.  In this
             same experiment, it must be demonstrated that the particle size
             and packing of the LSE cartridge or disk are acceptable.
             Consistent flow rate is an indication of acceptable particle
             size distribution and packing.

             10.2.1  A major source of potential  contamination  is the
                     liquid-solid extraction  (LSE) cartridge  which  could
                     contain phthalate esters,  silicon compounds, and other
                     contaminants that could  prevent  the determination  of
                     method  analytes  (5).   Although disks  are made  of a
                     teflon matrix, they may  still contain phthalate
                     materials.  Generally, phthalate esters  will be leached
                     from  the cartridges into methylene  chloride  and produce
                     a variable  background  that  is equivalent to  <2 /zg/L in
                     the water sample.   If  the  background  contamination is
                     sufficient  to prevent  accurate and  precise  analyses, the
                     condition must be corrected  before  proceeding  with the
                      initial demonstration.   Figure 2 shows unacceptable
                     background  contamination from a  poor  quality commercial
                     LSE cartridge.   The background contamination is the
                     large broad peak,  and  the  small  peaks are method
                    . analytes present at a  concentration equivalent to  2
                     /zg/L.   Several sources of  LSE cartridges may be
                     evaluated before an acceptable supply is identified.

             10.2.2  Other sources of background  contamination  are  solvents,
                     reagents, and glassware.   Background  contamination must
                     be reduced  to an acceptable  level before proceeding with


                                      337

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               the next section.   In  general,  background  from method
               analytes should be below the method  detection  limit.

      10.2.3   One liter of water should pass  through  a cartridge  in
               about 2 hrs with a partial  vacuum of about 13  cm (5 in.)
               of mercury.  The flow  rate through a disk  should be
               about 5-20 minutes for a liter  of drinking water, using
               full  aspirator or pump vacuum.   The  extraction time
               should not vary unreasonably among a set of LSE
               cartridges or disks.

10.3  Initial demonstration of laboratory  accuracy and precision.
      Analyze four to  seven replicates of  a laboratory fortified blank
      containing each  analyte of concern at a concentration  in the
      range of 2-5 /zg/L  (see regulations and maximum contaminant
      levels for guidance on appropriate concentrations).

      10.3.1   Prepare each  replicate by adding  an  appropriate aliquot
               of the primary dilution standard  solution,  or  another
               certified quality control  sample,  to reagent water.
               Analyze each  replicate according  to  the  procedures
               described in  Sect.  11  and on a  schedule  that results in
               the  analyses  of all replicates  over  a period of several
               days.

      10.3.2   Calculate the measured concentration of  each analyte in
               each  replicate,  the mean concentration of  each analyte
               in  all  replicates,  and mean  accuracy (as mean  percentage
               of true value)  for each analyte,  and the precision  (as
               relative standard  deviation,  RSD)  of the measurements
               for  each analyte.   Calculate the  MDL of  each analyte
               using  the procedures described  in  Sect.  13.112 (1).

      10.3.3   For  each analyte  and surrogate,  the  mean accuracy,
               expressed as  a  percentage  of the  true value, should be
               70-130% and the  RSD should be <30%.  Some  analytes,
               particularly  the  polycyclic  aromatic hydrocarbons with
               molecular weights  >250,  are  measured at  concentrations
               below  2 #g/L, with  a mean  accuracy of 35-130%  of true
               value.   The MDLs  should be sufficient to detect analytes
               at the regulatory  levels.   If these  criteria are not met
               for  an analyte,  take remedial action and repeat the
               measurements  for  that  analyte to  demonstrate acceptable
               performance before  samples are  analyzed.

      10.3.4   Develop and maintain a system of  control charts to plot
               the precision and  accuracy of analyte and  surrogate
              measurements  as  a  function of time.  Charting  of
               surrogate  recoveries is  an especially valuable activity
               since  these are present  in every  sample  and  the
               analytical  results will  form a  significant record of
              data quality.

10.4  Monitor the integrated areas of the quantisation ions of the
      internal  standards and surrogates in continuing  calibration
      checks (see Sect. 9.3.4).  In  laboratory fortified  blanks or
                              338

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       samples,  the  integrated  areas of  internal  standards  and
       surrogates will  not  be constant because the volume of the
       extract will  vary  (and is difficult  to keep constant).   But the
       ratios of the areas  should  be reasonably constant in laboratory
       fortified blanks and samples.  The addition of  10 /iL of  the
       recovery  standard, terphenyl-D14 (500 fig/ml),  to the extract is
       optional, and may  be used to monitor the recovery of internal
       standards and surrogates in laboratory fortified blanks  and
       samples.  Internal standard recovery should be  in excess of 70%.

 10.5   Laboratory reagent blanks.  With  each batch of  samples processed
       as  a group within  a  work shift, analyze a  laboratory reagent
       blank to  determine the background system contamination.  Any
       time a new batch of  LSE  cartridges or disks is  received, or new
       supplies  of other  reagents  are used, repeat the demonstration  of
       low background described in 10.2.

 10.6   With each batch of samples  processed as a  group within a work
       shift, analyze a single  laboratory fortified  blank  (LFB)
       containing each analyte  of  concern at a concentration as
       determined  in 10.3.   If  more than 20 samples  are  included  in a
       batch, analyze a LFB for every 20 samples. Use the  procedures
       described in  10.3.3  to evaluate the  accuracy  of the
       measurements, and  to estimate whether the  method detection
       limits can be obtained.  If acceptable accuracy and  method
       detection limits cannot  be  achieved, the problem must be located
       and corrected before further samples are analyzed.   Add  these
       results  to the on-going  control charts to  document  data  quality.

 10.7   Determine that the sample matrix  does not  contain materials that
       adversely affect method  performance. This is accomplished by
       analyzing replicates of  laboratory fortified  matrix  samples and
       ascertaining  that  the precision,  accuracy, and  method detection
       limits of analytes are  in the  same range as obtained with
       laboratory  fortified blanks.   If  a variety of different  sample
       matrices are  analyzed regularly,  for example, drinking water
       from groundwater and surface water sources, matrix  independence
       should be established for each.   A laboratory fortified  sample
       matrix  should be analyzed for  every  20 samples  processed in the
       same batch.

 10.8  With each set of field  samples  a  field reagent  blank (FRB)
       should  be analyzed.   The results  of  these  analyses  will  help
       define  contamination resulting  from  field  sampling  and
       transportation activities.

 10.9  At least quarterly,  replicates  of laboratory  fortified  blanks
       should  be analyzed to determine  the  precision of  the laboratory
       measurements.  Add these results  to  the  on-going  control charts
       to document data quality (as  in  Sect. 10.3).

10.10   At least quarterly,  analyze a  quality control sample from an
       external source.  If measured  analyte concentrations are not  of
       acceptable accuracy  (Sect.  10.3.3),  check  the entire analytical
       procedure to locate  and correct  the  problem source.


                               339

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      10.11  Numerous other quality control measures are incorporated into
             other parts of this procedure, and serve to alert the analyst to
             potential problems.

11.   PROCEDURE

      11.1  CARTRIDGE EXTRACTION

             11.1.1   Setup the  extraction  apparatus  shown' in  Figure  3A.  The
                      reservoir  is  not  required, but  recommended  for
                      convenient operation.  Water drains  from the  reservoir
                      through  the LSE cartridge and into a  syringe  needle
                      which is inserted through a rubber stopper  into the
                      suction  flask.  A slight vacuum of 13 cm (5 in.) of
                      mercury  is used during all operations with  the
                      apparatus.  The pressure used is critical as  a  vacuum >
                      than 13  cm may result in poor precision.  About 2 hrs is
                      required to draw  a liter of water through the system.

             11.1.2   Pour the water sample into the  2-L separatory funnel
                      with the stopcock closed, add 5 ml methanol,  and mix
                      well.  Residual chlorine should not be present  as a
                      reducing agent should have been added at the  time of
                      sampling.   Also the pH of the sample  should be  about 2.
                      If residual chlorine  is present and/or the  pH is >2, the
                      sample may be invalid.  Add a 100-juL  aliquot  of the
                      fortification solution (50 fig/ml) for internal  standards
                      and surrogates, and mix immediately until homogeneous.
                      The concentration of these compounds  in  the water should
                      be 5 fig/I.

             11.1.3   Flush each  cartridge with two 10 ml aliquots  of
                      methylene  chloride, followed by two 10 ml aliquots of
                      methanol,  letting the cartridge drain dry after each
                      flush.   These solvent flushes may be accomplished by
                      adding the  solvents directly to the solvent reservoir in
                      Figure 3A.  Add 10 ml of reagent water to the solvent
                      reservoir,  but before the reagent water  level drops
                      below the  top edge of the packing in the LSE  cartridge,
                      open the stopcock of the separatory funnel   and  begin
                      adding sample water to the solvent reservoir.   Close the
                      stopcock when an  adequate amount of sample  is in the
                      reservoir.

             11.1.4   Periodically open the stopcock  and drain a  portion of
                      the sample  water  into the solvent reservoir.  The water
                      sample will drain into the cartridge, and from  the exit
                      into the suction flask.  Maintain the packing material
                      in the cartridge  immersed in water at all times.  After
                      all of the  sample has passed through the LSE  cartridge,
                     wash the separatory funnel  and  cartridge with 10 mL of
                      reagent water, and draw air through the cartridge for 10
                     min.

             11.1.5  Transfer the 125-mL solvent reservoir and LSE cartridge
                      (from Figure 3A) to the elution apparatus (Figure 3B).

                                     340

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r\
                                 The same 125-mL solvent reservoir is used for both
                                 apparatus.  Wash the 2-liter separatory funnel with 5 ml
                                 of methylene chloride and collect the washings.  Close
                                 the stopcock on the 100-mL separatory funnel of the
                                 elution apparatus, add the washings to the reservoir and
                                 enough additional methylene chloride to bring the volume
                                 back up to 5 ml and elute the LSE cartridge.  Elute the
                                 LSE cartridge with an additional 5 ml of methylene
                                 chloride (10-mL total).  A small amount of nitrogen
                                 positive pressure may be used to elute the cartridge.
                                 Small amounts of residual water from the LSE cartridge
                                 will form an immiscible layer with the methylene
                                 chloride in the 100-mL separatory funnel.  Open the
                                 stopcock and allow the methylene chloride to pass
                                 through the drying column packed with anhydrous sodium
                                 sulfate (1-in) and into the collection vial.  Do not
                                 allow the water layer to enter the drying column.
                                 Remove the 100 mL separatory funnel and wash the drying
                                 column with 2 mL of methylene chloride.  Add this to the
                                 extract.  Concentrate the extract to 1 mL under a gentle
                                 stream of nitrogen.  If desired, gently warm the extract
                                 in a water bath to evaporate to between 0.5 - 1.0 mL
                                 (without gas flow).  Do not concentrate the extract to
                                 less than 0.5 mL (or dryness) as this will result in
                                 losses of analytes.  If desired, add an aliquot of the
                                 recovery standard to the concentrated extract to check
                                 the recovery of the internal standards (see Sect. 10.4).

                  11.2   DISK  EXTRACTION  (This may be manual or automatic)

                         11.2.1   Preparation of Disks

                                 11.2.1.1  Insert  the  disk into  the  47mm filter apparatus
                                           as  shown  in  Figure 4.   Wash  the  disk with  5mL
                                           methylene chloride (MeC12)  by adding the MeC12
                                           to  the  disk,  drawing  about  half  through the
                                           disk, allowing  it  to  soak the disk for  about a
                                           minute, then  drawing  the  remaining MeC12
                                           through the  disk.

                                 11.2.1.2  Pre-wet the  disk with  5 mL methanol  (MeOH)  by
                                           adding  the  MeOH to the disk  and  allowing it to
                                           soak  for  about  a minute,  then drawing most  of
                                           the remaining MeOH through.   A layer of MeOH
                                           must  be left  on the surface  of the disk, which
                                           should  not  be allowed  to  go  dry  from this
                                           point until  the end of the  sample  extraction.
                                           THIS  IS A CRITICAL STEP FOR  A UNIFORM FLOW AND
                                           GOOD  RECOVERY.

                                 11.2.1.3  Rinse the disk  with 5  mL  reagent water by
                                           adding  the water to the disk and drawing most
                                           through,  again  leaving a  layer on  the surface
                                           of  the disk.

                         11.2.2   Add 5 mL MeOH per liter of water sample.  Mix well.

                                                 341

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       11.2.3  Add the water sample to the reservoir and turn on the
               vacuum to begin the extraction.  Full aspirator vacuum
               may be used.  Particulate-free water may pass through
               the disk in as little as ten minutes or less.  Extract
               the entire sample, draining as much water from the
               sample container as possible.

       11.2.4  Remove the filtration top from the vacuum flask, but do
               .not disassemble the reservoir and fritted base.  Empty
               the water from the flask, and insert a suitable sample
               tube to contain the eluant.  The only constraint on the
               sample tube is that it fit around the drip tip of the
               fritted base.  Reassemble the apparatus.

       11.2.5  Add 5 ml methylene chloride to the sample bottle, and
               rinse the inside walls thoroughly.  Allow the methylene
               chloride to settle to the bottom of the bottle, and
               transfer to the disk with a pipet or syringe, rinsing
               the sides of the glass filtration reservoir  in the
               process.  Draw about half of the methylene chloride
               through the disk, release the vacuum, and allow the disk
               to soak for a minute.  Draw the remaining methylene
               chloride through the disk.

       11.2.6  Repeat the above step twice.  Pour the combined eluates
               through a small funnel with filter paper containing
               three grams of anhydrous sulfate.  Rinse the test tube
               and sodium sulfate with two 5 ml portions of methylene
               chloride.  Collect all the extract and washings in a
               concentrator tube.

       11.2.7  Concentrate the extract to 1 ml under a gentle stream of
               nitrogen.  If desired, gently warm the extract in a
               water bath or heating block to concentrate to between
               05. and 1 ml.  Do not concentrate the extract to less
               than 0.5 ml, since this will result in losses of
               analytes.

11.3   Analyze a 1-2 /tL aliquot with the GC/MS system under the same
       conditions used for the initial  and continuing calibrations
       (Sect. 9.2.3).

11.4   At the conclusion of data acquisition,  use the same software
       that was used in the calibration procedure to tentatively
       identify peaks in retention time windows of interest.  Use the
       data system software to examine the ion abundances of components
       of the chromatogram.   If any ion abundance exceeds the system
       working range,  dilute the sample aliquot and analyze the diluted
       aliquot.

11.5   Identification of analytes.  Identify a sample component by
       comparison of its mass spectrum (after background subtraction)
       to a reference spectrum in the user-created data base.   The GC
       retention time of the sample component should be within 10 sec
       of the time observed for that same compound when a calibration
       solution was analyzed.

                               342

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             11.5.1   In general,  all  ions that are present above 10% relative
                      abundance in the mass spectrum of the standard should be
                      present in the mass spectrum of the sample component and
                      should agree within absolute 20%.   For example, if an
                      ion has a relative abundance of 30% in the standard
                      spectrum, its abundance in the sample spectrum should be
                      in the range of  10 to 50%.  Some ions, particularly the
                      molecular ion, are of special  importance,  and should be
                      evaluated even if they are below 10% relative abundance.

             11.5.2   Identification is hampered when sample components  are
                      not resolved chromatographically and produce mass
                      spectra containing ions contributed by more than one
                      analyte.   When GC peaks obviously represent more than
                      one sample component (i.e.,  broadened peak with
                      shoulder(s)  or valley between two or more  maxima),
                      appropriate  analyte spectra and background spectra can
                      be selected  by examining plots of characteristic ions
                      for tentatively  identified components.  When analytes
                      coelute (i.e., only one GC peak is apparent),  the
                      identification criteria can be met but each analyte
                      spectrum will  contain extraneous ions contributed  by the
                      coeluting compound.

             11.5.3   Structural  isomers that produce very similar mass
                      spectra can  be explicitly identified only  if they  have
                      sufficiently different GC retention times.   See Sect.
                      9.2.4.1.   Acceptable resolution is achieved if the
                      height of the valley between two isomer peaks  is less
                      than 25% of  the  average height of the two  peak heights.
                      Otherwise,  structural  isomers  are  identified as isomeric
                      pairs.   Benzo[b]  and benzo[k]fluoranthene  are  measured
                      as an isomeric pair.

             11.5.4   Phthalate esters  and other background components appear
                      in variable  quantities in laboratory and field reagent
                      blanks,  and  generally cannot be accurately measured at
                      levels below about 2 jig/L.   Subtraction of the
                      concentration in  the blank from the concentration  in the
                      sample at or below the 2 jag/L  level  is not recommended
                      because the  concentration of the background in the  blank
                      is highly variable.

12.   CALCULATIONS

      12.1   Complete chromatographic  resolution is not necessary for
             accurate and precise measurements of analyte concentrations if
             unique ions with adequate intensities are available for
             quantitation.  For example, although two listed analytes,
             dibenz[a,h]anthracene and indeno[l,2,3,c,d]pyrene,  were not
             resolved with the GC conditions used, and produced mass spectra
             containing common ions, concentrations (Tables 3-6) were
             calculated by measuring appropriate characteristic ions.
                     i
             12.1.1   Calculate analyte  and  surrogate  concentrations.


                                     343

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                                      (A,.)  RF  V

                     where:
                                Cx  = concentration of analyte or  surrogate
                                         in pg/L  in the water  sample.
                                Ax  = integrated abundance of the
                                         quantitation  ion of the  analyte  in
                                         the sample.
                                Ais =  integrated abundance of the
                                         quantitation  ion of the  internal
                                         standard in the sample.
                                Qis =  total quantity  (in micrograms)  of
                                         internal standard added  to the water
                                         sample.
                                V   = original water  sample volume in liters.
                                RF  = mean response factor of analyte from
                                         the initial calibration.

             12.1.2  Alternatively,  use the GC/MS  system  software  or other
                     available proven software to  compute the concentrations
                     of the  analytes and surrogates  from  the  second or  third
                     order regression curves.

             12.1.3  Calculations  should utilize all  available  digits of
                     precision,  but  final  reported concentrations  should be
                     rounded to an  appropriate number of  significant figures
                      (one digit of uncertainity).  Experience indicates  that
                     three significant  figures may be used  for  concentrations
                     above 99 /Kj/L,  two significant  figures  for
                     concentrations  between  1-99 /tg/L,  and  one  significant
                     figure  for lower concentrations.

13.   METHOD PERFORMANCE

      13.1   Single laboratory accuracy  and precision data (Tables 3-7)  for
             each listed  analyte was obtained  at two  concentrations with the
             same extracts analyzed on more than two  different  instrument
             systems.   Seven  1-liter aliquots  of reagent water containing 2
             /ig/L of each  analyte, and five to seven  1-liter  aliquots of
             reagent water containing 0.2 /ig/L of  each analyte were analyzed
             with this  procedure.  Tables 8-10 list data gathered  using  C-18
             disks.  These data were results from  different extracts
             generated  by  a  volunteer laboratory,  Environmental  Health
             Laboratories.

             13.1.2  With these data, method  detection limits (MDL) were
                     calculated using the formula:

                     MDL - S t(n.1j1.alpha = 0-99)

             where:

                                        Student's t value for the  99%
t(n-i i-aipha = o 99i, = Student's t value  for  the
confidence level with n-1 degrees of freedom
                344

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                      n = number of replicates
                      S = standard deviation of replicate analyses.
       13.2  PROBLEM COMPOUNDS
             13.2.1
             13.2.2
             13.2.3
             13.2.4
            The common phthalate and adipate esters (compounds 14,
            21, and 23-26), which are widely used commercially,
            appear in variable quantities in laboratory and field
            reagent' blanks, and generally cannot be accurately or
            precisely measured at levels below about 2 /zg/L.
            Subtraction of the concentration in the blank from the
            concentration in the sample at or below the 2 fig/I level
            is not recommended because the concentrations of the
            background in blanks is highly variable.

            Some polycyclic aromatic hydrocarbons are rapidly
            oxidized  and/or chlorinated in water containing
            residual chlorine.  Therefore residual chlorine must be
            reduced before analysis.

            In water free of residual chlorine, some polycyclic
            aromatic hydrocarbons (for example, compounds 9, 12, 13,
            20, and 35) are not accurately measured because of low
            recoveries in the extraction process.

            Pentachlorophenol No. 40 and hexachlorocyclopentadiene
            No. 34 may not be accurately measured.
            Pentachlorophenol is a strong acid and elutes as a broad
            weak peak.  Hexachlorocyclopentadiene is susceptible to
            photochemical and thermal decomposition.
14.   REFERENCES
     1.
     2.
     3.
     4.
     5.
Glaser, J. A., D. L. Foerst, G. D. McKee, S. A. Quave, and W. L.
Budde, "Trace Analyses for Wastewaters," Environ. Sci. Techno!. 1981
15, 1426-1435.

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

"OSHA Safety and Health Standards, General Industry," (29CFR1910),
Occupational Safety and Health Administration, OSHA 2206, (Revised,
January 1976).

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

Junk, G.A., M. J. Ayery, J. J. Richard, "Interferences in Solid-
Phase Extraction Using C-18 Bonded Porous Silica Cartridges," Anal.
Chem. 1988, 60, 1347.
                                     345

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       TABLE  1.   ION ABUNDANCE CRITERIA FOR BIS(PERFLUOROPHENYL)PHENYL
                  PHOSPHINE (DECAFLUOROTRIPHENYLPHOSPHINE,  DFTPP)
Mass
        Relative Abundance
           Criteria _
                                     Purpose of Checkpoint1
 51    10-80% of the base peak
 68    <2% of mass 69
 70    <2% of mass 69
127    10-80% of the base peak
197    <2% of mass 198
198    base peak or >50% of 442
199    5-9% of mass 198
275    10-60% of the base peak
365    >1% of the base peak
441    Present and < mass 443
442    base peak or >50% of 198
443    15-24% of mass 442
                                     low mass sensitivity
                                     low mass resolution
                                     low mass resolution
                                     low-mid mass sensitivity
                                     mid-mass resolution
                                     mid-mass resolution and sensitivity
                                     mid-mass resolution and isotope ratio
                                     mid-high mass sensitivity
                                     baseline threshold
                                     high mass resolution
                                     high mass resolution and sensitivity
                                     high mass resolution and isotope ratio
1A11  ions are used primarily to check the mass  measuring  accuracy  of  the mass
spectrometer and data system, and this is the most important part  of the
performance test.  The three resolution checks, which include natural
abundance isotope ratios, constitute the next most important part  of the
performance test.  The correct setting of the baseline threshold,  as indicated
by the presence of low intensity ions, is the next most important  part of the
performance test. Finally, the ion abundance ranges are designed to encourage
some standardization to fragmentation patterns.
                                      346

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         TABLE 2.   RETENTION TIME DATA,  QUANTITATION IONS,  AND INTERNAL
                   STANDARD REFERENCES FOR METHOD ANALYTES.
  Compound
                       Compound
                        Number
         Retention
       Time(min:sec)
        Aa     Bb
                    Quantitation
                   	Ion fm/z)
                            Internal
                            Standard
                           Reference
 Internal  standards

 acenaphthene-D10
 phenanthrene-D10
 chrysene-D12
1
2
3
 4:49
 8:26
18:14
 7:45
11:08
19:20
164
188
240
Surrogate

perylene-D12
      23:37   22:55
                       264
Target analvtes

acenaphthylene

aldrin
anthracene
atrazine
benz[a]anthracene
benzo[b]fluoranthene
benzo[k]fluoranthene
benzo[a]pyrene
benzo[g,h,i]perylene
butyl benzylphthalate
chlordane components
    alpha-chlordane
    gamma-chlordane
    trans nonachlor
2-chlorobiphenyl
chrysene
dibenz[a,h]anthracene
di-n-butylphthalate
2,3-di chlorobi phenyl
diethylphthalate
di(2-ethylhexyl)
  phthalate
di(2~ethylhexyl)adi pate
dimethylphthalate
endrin
fluorene
heptachlor
heptachlor epoxide
       4:37
          7:25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
11:21
8:44
7:56
18:06
22:23
22:28
23:28
27:56
16:40
13:44
13:16
13:54
4:56
18:24
27:15
10:58
7:20
5:52
19:19
17:17
4:26
15:52
6:00
10:20
12:33
13:36
11:20
10:42
19:14
22:07
22:07
22:47
26:44
18:09
15:42
15:18
15:50
7:55
19:23
25:57
13:20
10:12
8:50
20:01
18:33
7:21
16:53
8:53
12:45
14:40
               152

                66
               178
               200/215
               228
               252
               252
               252
               276
               149

               375
               375
               409
               188
               228
               278
               149
               222
               149

               149
               129
               163
                81
               166
               100/160
                81/353
                1

                2
                2
                1/2
                3
                3
                3
                3
                3
                2/3

                2/3
                2/3
                2/3
                1
                3
                3
                2
                1
                1

                2/3
                2/3

               2/3
                1
               2
               2
                                     347

-------
                            TABLE"2.   (Continued)
Compound Retention Internal
Number Time(min:sec) Quantitation Standard
Comoound Aa Bb Ion (m/z) Reference
2,2l,3,3I,4,4',6-hepta-
chl orobi phenyl
hexachlorobenzene
2,2',4,4l,5,6'-hexa-
chl orobi phenyl
hexachl orocycl o-
pentadiene
indeno[l,2,3,c,d]pyrene
lindane
methoxychl or
2, 2', 3, 3', 4, 5', 6,6'-
octachl orobi phenyl
2,2',3',4,6-penta
chl orobi phenyl
pentachlorophenol
phenanthrene
pyrene
simazine
2 , 2 ' , 4 , 4 ' -t etrachl oro-
bi phenyl
toxaphene
2,4, 5-tri chl orobi phenyl
alachlor

31
32

33

34
35
36
37

38

39
40
41
42
43

44
45
46
47

18:25
7:37

14:34

3:36
27:09
8:17
18:34

18:38

12:50
8:11
8:35
13:30
7:47

11:01
11:30-23:30
9:23
""

19:25
10:20

16:30

6:15
25:50
10:57
19:30

19:33

15:00
10:51
11:13
15:29
10:35

13:25
13:00-21:30
11:59
13:19

394/396
284/286

360

237
276
181/183
227

430

326
266
178
202
201

292
159
256
160

3
1/2

2

1
3
1/2
3

3

2
2
2
.2/3
1/2

2
2
2
2
aSingle ramp linear temperature program conditions (Sect. 9.2.3.2).
''Multi-ramp linear temperature program conditions (Sect. 9.2.3.1).
                                      348

-------
TABLE 3. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF
         THE  METHOD ANALYTES AT  2 /iG/L WITH  LIQUID-SOLID  EXTRACTION
         AND  THE  ION TRAP MASS SPECTROMETER
Compound
Number
(Table 2)
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
Mean"
aSee Table
True
Cone.
(ua/U
5
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
8
2
2
2
2
25
2
2
Mean
Observed
Cone.
(ua/U
5.0
1.9
1.6
1.7
2.2
1.8
Std.
Dev.
(UQ/L)
0.3
0.2
0.2
0.1
0.3
0.2
not separated from
4.2
0.8
0.7
2.0
2.0
2.2
2.7
1.9
2.2
0.3
2.2
2.3
2.0
1.9
1.6
1.9
1.8
2.2
2.2
2.3
1.4
1.7
1.6
1.1
0.4
2.1
1.8
1.8
1.9
8.2
2.4
1.9
2.1
1.5
28.
1.7
1.8
4. Compounds 4, 40,
0.3
0.2
0.1
0.3
0.2
0.3
1.0
0.1
0.1
0.3
0.3
0.1
0.3
0.2
0.3
0.2
0.1
0.2
0.3
0.2
0.2
0.2
0.4
0.1
0.2
0.2
0.2
0.2
0.1
1.2
0.1
0.1
0.2
0.1
4.7
0.1
0.2
Rel.
Std.
Dev.
(%)
6.0
11.
13.
5.9
14.
11.
No. 11;
7.1
25.
14.
15.
10.
14.
37.
5.2
4.5
100.
14.
4.3
15.
11.
19.
11.
5.5
9.1
14.
8.7
14.
12.
25.
9.1
50.
9.5
11.
11.
5.3
15.
4.2
5.3
9.5
6.7
17.
5.9
15.
and 45 excluded
Mean Method Method
Accuracy Detection
(% of True Limit (MDL)
Conc.^ (nan \
100
95
80
85
110
90
measured
105
40
35
100
100
110
135
95
110
15
110
115
100
95
80
95
90
110
110
115
70
85
80
55
20
105
90
90
95
102
120
95
105
75
112
85
91
from the
a
a
a
a
a
a
with No. 11
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
u
a
a
a
a

15.

	 0.6 	
means.
                              349

-------
TABLE 4. ACCURACY AND PRECISION DATA FROM FIVE TO SEVEN DETERMINATIONS
         OF THE METHOD ANALYTES AT 0.2 /iG/L WITH LIQUID-SOLID EXTRACTION
         AND THE ION TRAP MASS SPECTROMETER
Compound True
Number Cone.
( Table 2^ (ua/L)
4 0.5
~
5
6
7
8
g
10
11
12
13
14
15
16
J. v
17
18
19
20
21
22
23
24
25
26
27
28
£i*W
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
M&an°
"Compounds
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.8
0.2
0.2
0.2
0.2

0.2
0.2
4, 40,
Mean
Observed Std.
Cone'. Dev.
(ua/L) (ua/L)
0.45 0.6
0.13 0.03
0.13 0.03
0.13 0.01
0.24 0.03
0.14 0.01
not separated from No
0.25 0.04
0.03 0.01
0.03 0.02
0.32 0.07
0.17 0.04
0.19 0.03
0.17 0.08
0.19 0.03
0.21 0.01
0.03 0.02
0.48 0.09
0.20 0.03
0.45 0.21
0.39 0.16
0.31 0.16
0.21 0.01
0.12 0.12
0.21 0.05
0.22 0.01
0.19 0.04
0.19 0.03
0.16 0.04
0.19 0.03
0.04 0.01
0.04 0.03
0.22 0.02
0.11 0.01
0.19 0.05
0.13 0.02
0.78 0.08
0.20 0.004
0.18 0.005
0.25 0.04
0.14 0.04
not measured at thi
0.13 0.02
0.18 0.04
Rel . Mean Method
Std. Accuracy
Dev. (% of True
(%) Cone.}
13.
23.
23.
7.7
13.
7.1
90
65
65
65
120
70
. 11; measured with
16.
33.
67.
22.
24.
16.
47.
16.
4.8
67.
19.
15.
47.
41.
52.
4.8
100.
24.
4.5
21.
16.
25.
16.
25.
75.
9.1
9.1
26.
15.
10.
2.0
2.8
16.
29.
s level
15.
25.
bZ
15
15
160
85
95
85
95
105
150
240
100
225
195
155
105
60
105
110
95
95
80
95
20
20
110
55
95
65
97
100
90
125
70

65
95
Method
Detection
Limit (MDL)
(ua/L}
0.1
0.1
0.1
0.04
0.1
0.04
No. 11
Of*
.2
0.04
0.1
0.3
0.2
0.1
0.3
0.1
0.04
0.1
0.3
0.1
0.8
0.6
0.6
0.04
0.5
0.2
0.04
0.2
0.1
0.1
0.1
0.03
0.1
0.1
0.04
0.2
0.1
0.3
0.01
0.02
0.2
0.1

0.06
0.16
and 45 excluded from the means.
                                   350

-------
         TABLE 5. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS
                  OF THE METHOD ANALYTES AT 2 nG/L WITH LIQUID-SOLID EXTRACTION
                  AND A MAGNETIC SECTOR MASS SPECTROMETER
Compound True
Number Cone.
(Table 2} fua/L>
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46h
Meanb
5
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
8
2
2
2
2
25
2
2
Mean
Observed
Cone.
(m!L\
5.7
1.9
1.6
2.2
2.4
2.2
Std.
Dev.
(ua/l)
0.34
0.22
0.18
0.67
0.46
0.87
not separated from
4.0
0.85
0.69
2.0
2.2
2.1
1.9
2.0
2.1
0.75
2.5
2.0
3.5
2.0
1.4
2.9
1.7
2.6
1.2
2.6
1.5
1.5
1.9
0.89
0.83
2.2
2.0
1.5
1.6
12.
2.3
2.0
2.5
1.6
28.
1.9
1.8
0.37
0.15
0.12
0.20
0.41
0.38
0.10
0.29
0.32
0.18
0.32
0.23
1.8
0.28
0.16
0.70
0.45
1.0
0.10
0.42
0.19
0.35
0.17
0.11
0.072
0.10
0.88
0.11
0.14
2.6
0.18
0.26
0.34
0.17
2.7
0.073
0.32
Rel.
Std.
Dev.
(%)
6.0
12.
11.
30.
19.
40
No. 11;
9.3
18.
17.
10.
19.
18.
5.2
14.
15.
24.
13.
12.
51.
14.
11.
24.
26.
38.
8.3
16.
13.
23.
8.9
12.
8.7
4.5
44.
7.3
8.8
22.
7.8
13.
14.
11.
10.
3.8
16.
Mean Method
Accuracy
(% of True
Cone.)
114
95
80
110
120
110
measured with
100
43
35
100
110
105
95
100
105
38
125
100
175
100
70
145
85
130
60
130
75
75
95
45
42
110
100
75
80
150
115
100
125
80
112
95
88
Method
Detection
Limit (MDL)
(ua/L)
a
a
a
a
a
a
No. 11
a
a
a
a
a
a
a
a
a
a
a
a
a *
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
9.

1. 	
aSee Table 6.  Compounds 4, 40, and 45 excluded from the means.
                                     351

-------
    TABLE 6.  ACCURACY AND PRECISION DATA FROM SIX OR SEVEN DETERMINATIONS
             OF THE METHOD ANALYTES AT 0.2 /iG/L WITH LIQUID-SOLID EXTRACTION
             AND A MAGNETIC SECTOR MASS SPECTROMETER.
Compound
Number
( Table 2)
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23 ,
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
Mean8
True
Cone.
rua/L)
0.5
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.8
0.2
0.2
0.2
0.2
Mean
Observed
Cone.
(U.Q/L)
0.67
0.11
0.11
0.14
0.26
0.24
Std.
Dev.
(UQ/L)
0.07
0.03
0.02
0.02
0.08
0.06
not separated from
0.40
0.08
0.07
0.33
0.19
0.17
0.19
0.17
0.27
0.09
1.1
0.18
0.29
0.42
0.32
0.20
0.53
0.18
0.11
0.33
0.17
0.11
0.17
0.05
0.08
0.27
0.24
0.15
0.13
1.8
0.21
0.19
0.27
0.13
0.10
0.02
0.01
0.16
0.02
0.08
0.04
0.02
0.08
0.01
1.2
0.05
0.17
0.23
0.16
0.09
0.30
0.03
0.05
0.08
0.01
0.04
0.03
0.02
0.06
0.03
0.09
0.02
0.02
0.82
0.07
0.04
0.07
0.03
Rel.
Std.
Dev.
m
9.4
24.
21.-
17.
31.
26.
No. 11;
25.
27.
22.
48.
13.
45.
18.
13.
28.
15.
109.
30.
59.
55.
50.
47.
57.
15.
42.
26.
7.1
40.
15.
35.
8.1
11.
39.
12.
13.
46.
33.
23.
27.
22.
Mean Method
Accuracy
(% of True
Cone.)
134
55
56
70
130
120
measured with
100
38
33
160
95
85
95
85
135
46
550
90
145
210
160
100
265
90
55
165
85
55
85
24
40
135
120
75
65
225
105
95
135
65
Method
Detection
Limit (MDL)
(ua/U
0.2
0.1
0.1
0.1
0.3
0.2
No. 11
0.3
0.1
0.1
0.5
0.1
0.3
0.1
0.1
0.3
0.1
4.
0.2
0.6
0.8
0.5
0.3
1.
0.1
0.2
0.3
0.04
0.2
0.1
0.1
0.02
0.1
0.3
0.1
0.1
3,
0.2
0.1
0.2
0.1
not measured at this level
0.2
0.2
0.16
0.21
0.04
0.09
23.
28.
80
102
0.12
0.3
Compounds 4,  40,  and 45 excluded from the means.
                                      352

-------
                TABLE 7.  ACCURACY AND PRECISION DATA FROM SEVEN
                         DETERMINATIONS AT 2 /iG/L WITH LIQUID-SOLID EXTRACTION
                         AND A QUADRUPOLE MASS SPECTROMETER


                       Mean             Rel .   Mean Method    Method
Compound    True     Observed    Std.   Std.    Accuracy     Detection
 Number     Cone.      Cone.     Dev.   Dev.   (% of True   Limit (MDL)
(Table 2)  (pg/L) _ (uQ/l)    (ua/l)  (%)      Cone.)
  47         2         2.4       0.4    16.      122           1.0
                                    353

-------
TABLE 8.  ACCURACY AND PRECISION DATA FROM SEVEN REPLICATES AT 0.2 /tG/L
           WITH LIQUID-SOLID C-18  DISK EXTRACTION  AND AN ION  TRAP MASS
           SPECTROMETER
Compound
Number
(Table 2}
1
4
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
Target
Concentration
(ua/l)
0.2
5.0
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
2.0
0.2
0.2
0.2
0.2
20.0
0.2
0.2
Standard
Deviation
(ua/l)
0.01
0.37
0.03
0.03
0.04
0.07
0.16
0.03
0.04
0.03
0.07
0.12
0.06
0.18
0.01
0.02
0.05
0.08
0.02
0.02
0.50
0.04
0.02
0.05
0.01
0.05
0.08
0.08
0.04
0.06
0.01
0.05
0.01
0.03
0.04
0.03

0.02
0.02
0.04
0.06
2.47
0.04
0.03
Relative
Deviation
m
5.3
7.4
13.2
13.7
22.4
33.2
77.6
13.7
21.7
14.9
32.5
61.1
31.9
91.3
7.2
10.9
22.9
40.3
9.7
11.9
252.0
20.8
7.6
25.4
7.3
22.9
38.9
38.0
17.7
31.9
5.2
27.0
6.5
13.4
21.1
15.1

12.2
10.2
18.8
28.1
12.3
21.4
14.7
Mean
(aa/LV
0.22
5.55
0.26
0.22
0.21
0.29
0.40
0.21
0.26
0.23
0.37
0.19
0.19
0.55
0.16
0.27
0.18
0.47
0.17
0.27
1.54
0.36
0.23
0.23
0.20
0.28
0.36
0.28
0.22
0.19
0.34
0.29
0.22
0.20
0.20
0.17

0.20
0.24
0.19
0.21
24.80
0.19
0.11
Accuracy
(% of tarqet)
110
111
130
108
105
147
199
107
128
115
183
95
93
276
78
136
90
233
87
133
771
180
117
117
101
139
181
141
109
96
170
143
110
100
99
84

102
121
94
107
123
95
55
                                   354

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TABLE 9.  ACCURACY AND PRECISION DATA FROM SEVEN REPLICATES AT 2.0 flG/L
          WITH  LIQUID-SOLID C-18 DISK EXTRACTION AND AN  ION TRAP MASS
          SPECTROMETER
Compound
Number
( Table 2)
I
4
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
. 27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
Target
Concentration
riia/L)
2
5
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
20
2
2
2
2
100
2
2
Standard
Deviation
rua/n
0.18
0.45
0.30
0.17
0.47
0.21
0.62
0.57
0.31
0.28
0.33
0.62
1.02
1.39
0.22
0.23
0.27
0.23
0.38
0.22
0.38
0.26
0.69
0.12
0.19
0.30
0.15
0.64
0.85
0.52
0.22
0.37
0.42
0.34
0.77
0.29
15.16
0.20
0.17
0.27
0.15
3.36
0.58
0.07
Relative
Deviation
(%)
9.2
9.1
14.8
8.6
23.5
10.4
30.9
28.7
15.6
13.9
16.7
31.1
51.2
69.3
11.2
11.6
13.4
11.3
18.9
11.1
19.1
12.8
34.6
6.1
9.7
15.0
7.4
32.2
42.3
25.9
11.0
18.3
21.2
16.8
38.5
14.7
75.8
9.9
8.3
13.3
7.4
3.4
28.8
3.5
Mean
(UQ/L)
2.00
5.22
2.14
2.25
2.78
2.21
2.84
2.30
2.61
2.28
2.92
1.21
1.92
3.29
2.52
1.99
2.25
2.45
2.35
2.23
3.25
2.49
1.80
1.97
2.15
2.10
2.41
2.46
1.96
2.05
1.42
2.31
2.69
2.34
0.97
2.11
19.51
2.20
2.34
2.37
2.11
98.33
1.65
1.55
Accuracy
(% of taraet}
100
104
107
112
139
111
142
115
130
114
146
61
96
164
126
100
113
123
117
111
163
124
90
98
108
105
121
123
98
102
71
115
134
117
49
106
98
110
117
119
106
98
82
77
                                 355

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TABLE 10.  MINIMUM DETECTION LIMITS FROM SEVEN REPLICATES USING
            LIQUID-SOLID  EXTRACTION C-18 DISKS AND AN  ION TRAP MASS
            SPECTROMETER

     Chemical  Name	Minimum Detection  Limits	

     Acenaphtyiene                             0.033
     Alachlor                                  0.092
     Aldrin                                    0.083
     Anthracene                                0.086
     Atrazine                                  0.140
     Benz[a]anthracene                        0.224
     Benzo[b]fluoranthene                     0.488
     Benzo[k]fluoranthene                     0.086
     Benzo[a]pyrene                           0.137
     Benzo[ghi]perylene                       0.094
     Butyl benzylphthalate                     0.204
     Chlordane-alpha                          0.384
     Chiordane-gamma                          0.200
     Chlordane (transnonachlor)                0.574
     Chrysene                                  0.068
     Dibenz[ah]anthracene                     0.144
     Di-n-butylphthalate                       0.253
     Diethylphthalate                         0.075
     Di(2-ethylhexyl)phthalate                1.584
     Di(2-ethlyhexyl)adipate                  0.131
     Dimethylphthalate                        0.048
     Endrin                                    0.160
     Fluorene                                  0.046
     Heptachlor                               0.144
     Heptachlorepoxide                        0.244
     Hexachlorobenzene                        0.111
     Hexachlorocyclopentadiene                0.039
     Indeno[123cd]pyrene                       0.170
     Lindane                                  0.041
     Methoxychlor                             0.084
     PCB-mono-Cl-isomer                       0.045
     PCB-di-Cl-isomer                         0.061
     PCB-tri-Cl-ISOMER                        0.135
     PCB-tetra-Cl-isomer                       0.177
     PCB-penta-Cl-isomer                       0.095
     PCB-hexa-Cl-isomer                       0.200
     PCB-hepta-Cl-isomer                       0.239
     PCB-octa-Cl-isomer                       0.133
     Pentachlorophenol                        47.648
     Phenanthrene                             0.076
     Pyrene                                    0.064
     Simazine                                  0.118
     Toxaphene                                7.763
                              356

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s
00
                                   357

-------
  s
M
8
EJ
e>
                                                                            cxa
                                                                              •cvi
                                          358

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                     2 Liter
                    separetory
                     funnel
                 125ml
                 solvent
                reservoir

               ground glass 1 14/35

               LSE cartridge

               rubber stopper


               No. 18-2O luer-lok
                   syringe needle
                     V1 liter
                   acuum flask
                                                          1 25 ml
                                                          solvent
                                                         reservoir

                                                         ground glass
                                                           114/35
                                                       LSE cartridge
                                                          10Oml
                                                         separator/
                                                           funnel
                   drying
                   column
               1.2cmx4Ocm
                                                         1O ml
                                                       graduated
                                                          vial
A. Extraction apparatus
                           FIGURE 3
B. Elution apparatus
                                  359

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S4
Si


8




I
  §
  M

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            METHOD 531.1.  MEASUREMENT OF N-METHYLCARBAMOYLOXIMES
       AND N-METHYLCARBAMATES IN WATER BY DIRECT AQUEOUS INJECTION HPLC
                        WITH POST COLUMN DERIVATIZATION
                                 Revision 3.0
D. L. Foerst - Method 531, Revision 1.0 (1985)

T. Engels (Battelle Columbus Laboratories) - National Pesticide Survey
  Method 5, Revision 2.0 (1987)

R. L. Graves - Method 531.1, Revision 3.0 (1989)
                  ENVIRONMENTAL  MONITORING  SYSTEMS  LABORATORY
                      OFFICE OF RESEARCH AND DEVELOPMENT
                     U.S. ENVIRONMENTAL PROTECTION AGENCY
                          •  CINCINNATI,  OHIO  45268
                                     361

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                                 METHOD 531.1

                    MEASUREMENT OF N-METHYLCARBAMOYLOXIMES
       AND N-HETHYLCARBAHATES IN WATER BY DIRECT AQUEOUS INJECTION HPLC
                        WITH POST  COLUMN  DERIVATIZATION


1.   SCOPE AND APPLICATION

     1.1  This is a high performance liquid chromatographic (HPLC) method
          applicable to the determinations of certain N-methylcarbamoyloximes
          and N-methylcarbamates in ground water and finished drinking
          water(l).  The following compounds can be determined using this
          method:

                                         Chemical Abstract Services
            Analvte                           Registry Number

          Aldicarb                                116-06-3
          Aldicarb sulfone                       1646-88-4
          Aldicarb sulfoxide                     1646-87-3
          Baygon                                  114-26-1
          Carbaryl                                 63-25-2
          Carbofuran                             1563-66-2
          3-Hydroxycarbofuran                   16655-82-6
          Methiocarb                             2032-65-7
          Methomyl                              16752-77-5
          Oxamyl                                23135-22-0

     1.2  This method has been validated in a single laboratory and estimated
          detection limits  (EDLs)  have been determined for the analytes above
          (Sect.12).  Observed detection limits may vary between ground
          waters, depending upon the nature of interferences in the sample
          matrix and the specific instrumentation used.

     1.3  This method is restricted to use by or under the supervision of
          analysts experienced in the use of liquid chromatography and in the
          interpretation of liquid chromatograms.  Each analyst must demon-
          strate the ability to generate acceptable results with this method
          using the procedure described in Sect. 10.3.

     1.4  When this method  is used to analyze unfamiliar samples for any or
          all of the analytes above, analyte identifications should be
          confirmed by at least one additional qualitative technique.

2.   SUMMARY OF METHOD

     2.1  The water sample  is filtered and a 400-ftL aliquot is injected into a
          reverse phase HPLC column.  Separation of the analytes is achieved
          using gradient elution chromatography.  After elution from the HPLC
          column, the analytes are hydrolyzed with 0.05 N sodium hydroxide
          (NaOH) at 95°C.  The methyl amine formed during hydrolysis is

                                      362

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          reacted with o-phthalaldehyde (OPA) and 2-mercaptoethanol to form a
          highly fluorescent derivative which is detected by a fluorescence
          detector (2).

3.   DEFINITIONS

     3.1  Internal standard — A pure analyte(s) added to a solution in known
          amount(s) and used to measure the relative responses of other method
          analytes and surrogates that are components of the same solution.
          The internal standard must be an analyte that is not a sample
          component.

     3.2  Surrogate analyte — A pure analyte(s), which is extremely unlikely
          to be found in any sample, and which is added to a sample aliquot in
          known amount(s) before extraction and is measured with the same
          procedures  used to measure other sample components.   The purpose of
          a surrogate analyte is to monitor method performance with each
          sample.

     3.3  Laboratory  duplicates (LD1 and LD2) — Two sample aliquots taken in
          the analytical laboratory and analyzed separately with identical
          procedures.  Analyses of LD1 and LD2 give a measure  of the precision
          associated  with laboratory procedures, but not with  sample
          collection, preservation, or storage procedures.

     3.4  Field duplicates (FD1 and FD2) — Two separate samples collected at
          the same time and place under identical circumstances and treated
          exactly the same throughout field and laboratory procedures.
          Analyses of FD1 and FD2 give a measure of the precision associated
          with sample collection, preservation and storage, as well as  with
          laboratory  procedures.

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

     3.6  Field reagent blank (FRB) — Reagent water placed in a sample
          container in the laboratory and treated as a sample  in all  respects,
          including exposure to sampling site conditions,  storage,
          preservation and all analytical  procedures.   The purpose  of the FRB
          is to determine if method analytes or other interferences are
          present  in  the field environment.

     3.7  Laboratory  performance check solution (LPC)  — A solution of  method
          analytes, surrogate compounds, and internal  standards used to
          evaluate the performance of the instrument system with respect to a
         .defined  set of method criteria.
                                     363

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     3.8  Laboratory fortified blank (LFB) — An aliquot of reagent water to
          which known quantities of the method analytes are added in the
          laboratory.  The LFB is analyzed exactly like a sample, and its
          purpose is to determine whether the methodology is in control, and
          whether the laboratory is capable of making accurate and precise
          measurements at the required method detection limit.

     3.9  Laboratory fortified sample matrix (LFM) — An aliquot of an
          environmental sample to which known quantities of the method
          analytes are added in the laboratory.  The LFM is analyzed exactly
          like a sample, and its purpose is to determine whether the sample
          matrix contributes bias to the analytical  results.  The background
          concentrations of the analytes in the sample matrix must be
          determined in a separate aliquot and the measured values in the LFM
          corrected for background concentrations.

     3.10 Stock standard solution — A concentrated solution containing a
          single certified standard that is a method analyte, or a
          concentrated solution of a single analyte prepared in the laboratory
          with an assayed reference compound.  Stock standard solutions are
          used to prepare primary dilution standards.

     3.11 Primary dilution standard solution — A solution of several
          analytes prepared in the laboratory from stock standard solutions
          and diluted as needed to prepare calibration solutions and other
          needed analyte solutions.

     3.12 Calibration standard (CAL) — A solution prepared from the primary
          dilution standard solution and stock standard solutions of the
          internal standards and surrogate analytes.  The CAL solutions are
          used to calibrate the instrument response with respect to analyte
          concentration.

     3.13 Quality control sample (QCS) — A sample matrix containing method
          analytes or a solution of method analytes in a water miscible
          solvent which is used to fortify reagent water or environmental
          samples.  The QCS is obtained from a source external to the
          laboratory, and is used to check laboratory performance with
          externally prepared test materials.

4.   INTERFERENCES

     4.1  Method interferences may be caused by contaminants in solvents,
          reagents, glassware and other sample processing apparatus that lead
          to discrete artifacts or elevated baselines in liquid chromatograms.
          Specific sources of contamination have not been identified.  All
          reagents and apparatus must be routinely demonstrated to be free
          from interferences under the conditions of the analysis by running
          laboratory reagent blanks as described in Sect. 10.2.

          4.1.1   Glassware must be scrupulously cleaned.(2)  Clean all
                  glassware as soon as possible after use by thoroughly

                                      364

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                  rinsing with the last solvent used in it.  Follow by washing
                  with hot water and detergent and thorough rinsing with tap
                  and reagent water.  Drain dry, and heat in an oven or muffle
                  furnace at 450°C for 1 hour.  Do not heat volumetric ware.
                  Thermally stable materials might not be eliminated by this
                  treatment.  Thorough rinsing with acetone may be substituted
                  for the heating.  After drying and cooling, seal and store
                  glassware in a clean environment to prevent any accumulation
                  of dust or other contaminants.  Store inverted or capped
                  with aluminum foil.

          4.1.2   The use of high purity reagents and solvents helps to
                  minimize interference problems.  Purification of solvents by
                  distillation in all-glass systems may be required.  WARNING:
                  When a solvent is purified, stabilizers added by the
                  manufacturer are removed, thus potentially making the
                  solvent hazardous.  Also, when a solvent is purified,
                  preservatives added by the manufacturer are removed, thus
                  potentially reducing the shelf-life.

     4.2  Interfering contamination may occur when a sample containing low
          concentrations of analytes is analyzed immediately following a
          sample containing relatively high concentrations of analytes.  A
          preventive technique is between-sample rinsing of the sample syringe
          and filter holder with two portions of reagent water.  After
          analysis of a sample containing high concentrations of analytes, one
          or more laboratory method blanks should be analyzed.

     4.3  Matrix interference may be caused by contaminants that are present
          in the sample.  The extent of matrix interference will -vary consid-
          erably from source to source, depending upon  the water sampled.
          Positive identifications must be confirmed.
5.   SAFETY
     5.1  The toxicity or carcinogenicity of each reagent used in this method
          has not been precisely defined; however, each chemical  compound must
          be treated as a potential health hazard.  Accordingly,  exposure to
          these chemicals must be reduced to the lowest possible  level.  The
          laboratory is responsible for maintaining a current awareness file
          of OSHA regulations regarding the safe handling of the  chemicals
          specified in this method.  A reference file of material safety data
          sheets should also be made available to all personnel  involved in
          the chemical analysis.  Additional references to laboratory safety
          are available and have been identified (4-6) for the information of
          the analyst.

     5.2  WARNING:  When a solvent is purified,  stabilizers added by the
          manufacturer are removed, thus potentially making the solvent
          hazardous.
                                     365

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6.   APPARATUS AND EQUIPMENT  (All specifications are suggested.  Catalog
     numbers are included for illustration only.)
     6.1  SAMPLING EQUIPMENT
          6.1.1   Grab sample bottle — 60-mL screw cap vials (Pierce No.
                  13075 or equivalent) and caps equipped with a PTFE-faced
                  silicone septa (Pierce No.  12722 or equivalent).  Prior to
                  use, wash vials and septa as described in Sect. 3.1.1.
     6.2  BALANCE — Analytical, capable of accurately weighing to the nearest
          0.0001 g.
     6.3  FILTRATION APPARATUS
          6.3.1   Macrofiltration -- To filter derivatization solutions and
                  mobile phases used in HPLC.  Recommend using 47 mm filters
                  (Millipore Type HA, 0.45 /on for water and Millipore Type FH,
                  0.5 ion for organics or equivalent).
          6.3.2   Microfiltration — To filter samples prior to HPLC analysis.
                  Use 13 mm filter holder (Millipore stainless steel XX300/200
                  or equivalent), and 13 mm diameter 0.2 urn polyester filters
                  (Nuclepore 180406 or equivalent).
     6.4  SYRINGES AND SYRINGE VALVES
          6.4.1   Hypodermic syringe — 10-mL glass, with Luer-Lok tip.
          6.4.2   Syringe valve — 3-way (Hamilton HV3-3 or equivalent).
          6.4.3   Syringe needle — 7 to 10-cm long, 17-gauge, blunt tip.
          6.4.4   Micro syringes -- various sizes.
     6.5  MISCELLANEOUS
          6.5.1   Solution storage bottles — Amber glass, 10- to 15-mL
                  capacity with TFE-fluorocarbon-lined screw cap.
          6.5.2   Helium, for degassing solutions and solvents.
     6.6  HIGH PERFORMANCE LIQUID CHROMATOGRAPH (HPLC)
          6.6.1   HPLC system capable of injecting 200- to 400-#L aliquots,
                  and performing binary linear gradients at a constant flow
                  rate.  A data system is recommended for measuring peak
                  areas.  Table 1 lists retention times observed for method
                  analytes using the columns and analytical conditions
                  described below.
                                      366

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     6.6.2   Column  1  (Primary column) — 150 mm long ,x 3.9 mm  I.D.
             stainless steel packed with 4 fan NovaPak CIS.  Mobil Phase
             is established at 10:90 methanol:  water, hold 2 min., then
             program as a linear gradient to 80:20 methanol:  water in 25
             min.  Alternative columns may be used in accordance with the
             provisions described in Sect. 10.4.

     6.6.3   Column  2  (Alternative column)* -- 250 mm long x 4.6 mm I.D.
             stainless steel packed with 5 /an Beckman Ultrasphere ODS.
             Mobile  phase is established at 1.0 mL/min as a linear
             gradient from 15:85 methanol:  water to methanol in 32 min.
             Data presented in this method were obtained using this
             column.  * Newer manufactured columns have not been able to
             resolve aldicarb sulfone from oxamyl. '"""<•;.

     6.6.4   Column  3 (Alternative column) -- 250 mm long x 4.6 mm I.D.
             stainless steel packed with 5 fim Supelco LC-1.  Mobile phase
             is established at 1.0 mL/min as a linear gradient from 15:85
             methanol:  water to methanol in 32 min.

     6.6.5   Post column reactor — Capable of mixing reagents into the
             mobile  phase.  Reactor should be constructed using PTFE
             tubing  and equipped with pumps to deliver 0.1 to 1.0 mL/min
             of each reagent;  mixing tees; and two 1.0-mL delay coils,
             one thermostated at 95°C (ABI URS 051 and URA 100 or equiva-
             lent).

     6.6.6   Fluorescence detector — Capable of excitation at 330 nm
             (nominal) and detection of emission energies greater than
             418 nm.  A Schoffel  Model  970 fluorescence detector was used
             to generate the validation data presented in this method.

REAGENTS AND CONSUMABLE MATERIALS — WARNING:  When a solvent is
purified, stabilizers added by the manufacturer are removed, thus
potentially making the solvent hazardous.  Also, when a solvent is
purified, preservatives added by the manufacturer are removed, thus
potentially reducing the shelf-life.

7.1  REAGENT WATER — Reagent  water is  defined as water that is
     reasonably free of contamination that would prevent the
     determination of any analyte of interest.   Reagent water used to
     generate the validation data in this method was  distilled water
     obtained from the Magnetic Springs Water Co.,  1801  Lone Eaqle St.,
     Columbus,  Ohio 43228.

7.2  METHANOL — Distilled-in-glass  quality or equivalent.

7.3  HPLC MOBILE PHASE

     7.3.1   Water -- HPLC  grade  (available  from Burdick and Jackson).
                                367

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     7.3.2   Methanol  -- HPLC grade.   Filter and degas with helium before
             use.

7.4  POST COLUMN DERIVATIZATION SOLUTIONS

     7.4.1   Sodium hydroxide, 0.05 N — Dissolve 2.0 g of sodium
             hydroxide (NaOH) in reagent water.   Dilute to 1.0 L with
             reagent water.  Filter and degas with helium just before
             use.

     7.4.2   2-Hercaptoethanol (1+1)  — Mix 10.0 mL of 2-mercapto-ethanol
             and 10.0 mL of acetonitrile.  Cap.   Store in hood (CAUTION
             — stench).

     7*.4.3   Sodium borate (0.05 N) — Dissolve 19.1 g of sodium borate
             (Na2B407 ' 10H20)  in  reagent water.   Dilute to 1.0 L with
             reagent water.  The sodium borate will completely dissolve
             at room temperature if prepared a day before use,

     7.4.4   OPA reaction solution — Dissolve 100 ± 10 mg of o-phthal-
             aldehyde (mp 55-58°C) in 10 mL of methanol.  Add to 1.0 L of
             0.05 N sodium borate.  Mix, filter, and degas with helium.
             Add 100 (il of 2-mercaptoethanol (1+1) and mix.  Make up
             fresh solution daily.

7.5  MONOCHLOROACETIC ACID BUFFER (pH3) — Prepare by mixing 156 mL of
     2.5 M monochloroacetic acid and 100 mL 2.5 M potassium acetate.

7.6  4-BROMO-3,5-DIMETHYLPHENYL N-METHYLCARBAMATE (BDMC) — 98% purity,
     for use as internal standard (available from Aldrich Chemical Co.).

7.7  STOCK STANDARD SOLUTIONS (1.00 jig/M-) — Stock standard solutions
     may be purchased as certified solutions or prepared from pure
     standard materials using the following procedure:

     7.7.1   Prepare stock standard solutions by accurately weighing
             approximately 0.0100 g of pure material.  Dissolve the
             material in HPLC quality methanol and dilute to volume  in a
             10-mL volumetric flask.   Larger volumes may be used at the
             convenience of the analyst.  If compound purity is certified
             at 96% or greater, the weight may be used without correction
             to calculate the concentration of the stock standard.
             Commercially prepared stock standards may be used at any
             concentration if they are certified by the manufacturer or
             by an independent source.

     7.7.2   Transfer the stock standard solutions into TFE-fluoro-
             carbon-sealed screw cap vials.  Store at room temperature
             and protect from light.
                                 368

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          7.7.3   Stock standard solutions should be replaced after two months
                  or sooner if comparison with laboratory fortified blanks, or
                  QC samples indicate a problem.

     7.8  INTERNAL STANDARD SOLUTION — Prepare an internal standard
          fortification solution by accurately weighing approximately 0.0010 g
          of pure BDMC.  Dissolve the BDMC in pesticide-quality methanol and
          dilute to volume in a 10-mL volumetric flask.  Transfer the internal
          standard fortification solution to a TFE-fluorocarbon-sealed screw
          cap bottle and store at room temperature.  Addition of 5 /aL of the
          internal standard fortification solution to 50 mL of sample results
          in a final internal standard concentration of 10 /zg/L.  Solution
          should be replaced when ongoing QC (Sect. 10) indicates a problem.
          Note:  BDMC has been shown to be an effective internal standard for
          the method analytes (1), but other compounds may be used, if the
          quality control requirements in Sect. 9 are met.

     7.9  LABORATORY PERFORMANCE CHECK SOLUTION — Prepare concentrate by
          adding 20 juL of the 3-hydroxycarbofuran stock standard solution,
          1.0 mL of the aldicarb sulfoxide stock standard solution, 200 /tL of
          the methiocarb stock standard solution, and 1 mL of the internal
          standard fortification solution to a 10-mL volumetric flask.  Dilute
          to volume with methanol.  Thoroughly mix concentrate.  Prepare check
          solution by placing 100 fil of the concentrate solution into a 100-mL
          volumetric flask.  Dilute to volume with buffered reagent water.
          Transfer to a TFE-fluorocarbon-sealed screw cap bottle and store at
          room temperature.  Solution should be replaced when ongoing QC
          (Sect. 10) indicates a problem.

8.   SAMPLE COLLECTION. PRESERVATION AND HANDLING

     8.1  Grab samples must be collected in glass containers.  Conventional
          sampling practices (8) should be followed; however, the bottle must
          not be prerinsed with sample before collection.

     8,2  SAMPLE PRESERVATION/PH ADJUSTMENT ~ Oxamyl, 3-hydroxycarbofuran,
          aldicarb sulfoxide, and carbaryl can all degrade quickly in neutral
          and basic waters held at room temperature. (6,7)  This short term
          degradation is of concern during the time samples are being shipped
          and the time processed samples are held at room temperature in
          autosampler trays.  Samples targeted for the analysis of these three
          analytes must be preserved at pH 3.  The pH adjustment also
          minimizes analyte biodegradation.

          8.2.1   Add 1.8 mL of monochloroacetic acid buffer to the 60-mL
                  sample bottle.  Add buffer to the sample bottle at the
                  sampling site or in the laboratory before shipping to the
                  sampling site.

          8.2.2   If residual chlorine is present, add 80 mg of sodium thio-
                  sulfate per liter of sample to the sample bottle prior to
                  collecting the sample.

                                     369

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          8.2.3   After sample is collected in bottle containing buffer, seal
                  the sample bottle and shake vigorously for 1 min.

          8.2.4   Samples must be iced or refrigerated at 4°C from the time of
                  collection until storage.  Samples must be stored at -10°C
                  until analyzed.  Preservation study results indicate that
                  method analytes are stable in water samples for at least 28
                  days when adjusted to pH 3 and stored at -10°C.  However,
                  analyte stability may be effected by the matrix; therefore,
                  the analyst should verify that the preservation technique is
                  applicable to the samples under study.

9.   CALIBRATION

     9.1  Establish HPLC operating parameters equivalent to those indicated in
          Sect. 6.6.  The HPLC system may be calibrated using either the
          internal standard technique (Sect. 9.2) or the external standard
          technique (Sect. 9.3).

     9.2  INTERNAL STANDARD CALIBRATION PR9CEDURE.  The analyst must select
          one or more internal standards similar in analytical behavior to the
          analytes of interest.  The analyst must further demonstrate that the
          measurement of the internal standard is not affected by method or
          matrix interferences.  BDMC has been identified as a suitable
          internal standard.

          9.2.1   Prepare calibration standards at a minimum of three
                  (recommend five) concentration levels for each analyte of
                  interest by adding volumes of one or of the more stock
                  standards to a volumetric flask.  To each calibration
                  standard, add a known constant amount of one or more
                  internal standards, and dilute to volume with buffered
                  reagent water.  To prepare buffered reagent water, add 10 mL
                  of 1.0 M monochloroacetic acid buffer to 1 L of reagent
                  water.  The lowest standard should represent analyte
                  concentrations near, but above, their respective EDLs.  The
                  remaining standards should bracket the analyte concen-
                  trations expected in the sample extracts, or should define
                  the working range of the detector.

          9.2.2   Analyze each calibration standard according to the procedure
                  (Sect. 11.2).  Tabulate peak height or area responses
                  against concentration for each compound and internal
                  standard.  Calculate response factors (RF) for each analyte,
                  surrogate and internal standard using Equation 1.

                    RF =     (As)(cis)       Equation 1
                             (A

                    where:
                                     370

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               As  = Response for the analyte to be measured.
               Ais  = Response for the internal standard.
               Cjs  = Concentration of the  internal  standard wg/L).
               C   = Concentration of the  analyte to be measured
                     W/L).

     9.2.3   If the RF value over the working range is constant (20% RSD
             or less) the average RF can be used for calculations.
             Alternatively, the results can be used to plot a calibration
             curve of response ratios (AsxAis) vs. Cs.

     9.2.4   The working calibration curve or RF must be verified on each
             working shift by the measurement of one or more calibration
             standards.  If the response for any analyte varies from the
             predicted response by more than ±20%, the test must be
             repeated using a fresh  calibration  standard.  If the
             repetition also fails,  a new calibration curve must be
             generated for that analyte using freshly'prepared standards.

     9.2.5   Single point calibration is a viable alternative to a
             calibration curve.  Prepare single  point standards from the
             secondary dilution standards.  The  single point standards
             should be prepared at a concentration that deviates from the
             sample extract response by no more  than 20%.

     9.2.6   Verify calibration standards  periodically, recommend at
             least quarterly, by analyzing a standard prepared from
             reference material obtained from an independent source.
             Results from these analyses must be within the limits used
             to routinely check calibration.

9.3  EXTERNAL STANDARD CALIBRATION PROCEDURE

     9.3.1   Prepare calibration standards at a  minimum of three
             (recommend five) concentration levels for each analyte of
             interest by adding volumes of one or more stock standards to
             a volumetric flask.  Dilute to volume with buffered reagent
             water.  The lowest standard should  represent analyte
             concentrations near, but above, the respective EDLs.   The
             remaining standards should bracket  the analyte
             concentrations expected in the sample extracts,  or should
             define the working range of the detector.

     9.3.2   Starting with the standard of lowest concentration, analyze
             each calibration standard according to Sect. 11.2 and
             tabulate responses (peak height or  area) versus the
             concentration in the standard.  The results can be used to
             prepare a calibration curve for each compound.
             Alternatively, if the ratio of response to concentration
             (calibration factor) is a constant  over the working range
             <20% relative standard  deviation),  linearity through  the


                                 371

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                  origin can be assumed and the average ratio or calibration
                  factor can be used in place of a calibration curve.

          9.3.3   The working calibration curve or calibration factor must be
                  verified on each working day by the measurement of a minimum
                  of two calibration check standards, one at the beginning and
                  one at the end of the analysis day.  These check standards
                  should be at two different concentration levels to verify
                  the concentration curve.  For extended periods of analysis
                  (greater than 8 hr), it is strongly recommended that check
                  standards be interspersed with samples at regular intervals
                  during the course of the analyses.  If the response for any
                  analyte varies from the predicted response by more than
                  ±20%, the test must be repeated using a fresh calibration
                  standard.  If the results still do not agree, generate a new
                  calibration curve or use a single point calibration standard
                  as described in Sect. 9.3.3.

          9.S-.4   Single point calibration is a viable alternative to a
                  calibration curve.  Prepare single point standards from the
                  secondary dilution standards.  The single point standard's
                  should be prepared at a concentration that deviates from the
                  sample extract response by no more than 20%.

          9.3.5   Verify calibration standards periodically, recommend at
                  least quarterly, by analyzing a standard prepared from
                  reference material obtained from an independent source.
                  Results from these analyses must be within the limits used
                  to routinely check calibration.

10.   QUALITY CONTROL

     10.1  Minimum quality control  (QC)  requirements are initial  demonstration
           of laboratory capability,  monitoring internal  standard peak area or
           height in each sample and blank (when internal  standard calibration
           procedures are being employed),  analysis  of laboratory reagent
           blanks,  laboratory fortified samples,  laboratory fortified blanks
           and QC samples.

     10.2  LABORATORY REAGENT BLANKS.   Before processing any samples,  the
           analyst must demonstrate that all  glassware and reagent
           interferences are under control.   Each time a set of samples is
           extracted or reagents are changed,  a laboratory reagent blank (LRB)
           must be analyzed.   If within the retention time window of any
           analyte of interest the LRB produces a peak that would prevent the
           determination of that analyte,  determine  the source of
           contamination and eliminate the interference before processing
           samples.
                                     372

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10.3  INITIAL DEMONSTRATION OF CAPABILITY.

      10.3.1  Select a representative concentration (about 10 times EDL)
             for each analyte.  Prepare a sample concentrate (in
             methanol) containing each analyte at 1000 times selected
             concentration.  With a syringe, add 50 /iL of the
             concentrate to each of at least four 50-mL aliquots of
             reagent water, and analyze each aliquot according to
             procedures beginning in Sect. 11.

      10.3.2  For each analyte the recovery value for all four of these
             samples must fall in the range of R ± 30% (or within R ±
             3SR if broader)  using the values for R and SR  for  reagent
             water in Table 2.  For those compounds that meet the
             acceptance criteria, performance is judged acceptable and
             sample analysis may begin.  For those compounds that fail
             these criteria,  this procedure must be repeated using four
             fresh samples until satisfactory performance has been
             demonstrated.

      10.3.3  The initial demonstration of capability is used primarily
             to preclude a laboratory from analyzing unknown samples via
             a new, unfamiliar method prior to obtaining some experience
             with it.  It is expected that as laboratory personnel gain
             experience with this method the quality of data will
             improve beyond those required here.

10.4  The analyst is permitted to modify HPLC columns, HPLC conditions,
      internal standards or detectors to improve  separations or lower
      analytical costs.  Each time such method modifications are made,
      the analyst must repeat the procedures  in Sect. 10.3.

10.5  ASSESSING THE INTERNAL STANDARD

     10.5.1  When using the internal standard calibration procedure, the
            analyst is expected to monitor the IS response (peak area or
            peak height) of all samples during each analysis day.  The
            IS response for any sample chromatogram should not deviate
            from the daily calibration check standard's IS response by
            more than 30%.

     10.5.2  If >30% deviation occurs with an individual extract,
            optimize instrument performance and  inject a second aliquot.

            10.5.2.1  If the  reinjected aliquot produces an acceptable
                      internal  standard response, report results for
                      that aliquot.

            10.5.2.2  If a deviation of greater than  30% is obtained for
                      the reinjected extract, analysis  of the  sample
                      should  be repeated beginning with Sect.  11,

                                373

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                      provided the samples is still  available.
                      Otherwise, report results obtained from the
                      reinjected extract, but annotate as suspect.

     10.5.3  If consecutive samples fail the IS response acceptance
            criterion, immediately analyze a calibration check standard.

            10.5.3.1  If the check standard provides a response factor
                      (RF) within 20% of the predicted value, then
                      follow procedures itemized in  Sect. 10.5.2 for
                      each sample failing the IS response criterion.

            10.5.3.2  If the check standard provides a response factor
                      which deviates more than 20% of the predicted
                      value,  then the analyst must recalibrate, as
                      specified in Sect. 9.

10.6 ASSESSING LABORATORY  PERFORMANCE  -  LABORATORY  FORTIFIED BLANKS

     10.6.1  The laboratory must analyze at least one laboratory
             fortified blank (LFB) sample with every 20 samples or one
             per sample set (all samples analyzed within a 24-h period)
             whichever is greater.  The fortification concentration of
             each analyte in the LFB should be 10 times EDL or the MCL,
             whichever is less.  Calculate accuracy as percent recovery
             (X,-).   If the recovery of any analyte falls outside the
             control limits (see Sect. 10.7.2), that analyte is judged
             out of control, and the source of the problem must be
             identified and resolved before continuing analyses.

     10.6.2  Until  sufficient data become available  from within their
             own laboratory, usually a minimum of results from 20 to 30
             analyses, the laboratory should assess  laboratory
             performance against the control limits  in Sect. 10.3.2 that
             are derived from the data in Table 2.  When sufficient
             internal performance data becomes available, develop
             control limits from the mean percent recovery (X) and
             standard deviation (S) of the percent recovery.  These data
             are used to establish upper and lower control limits as
             fol1ows:

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

             After each five to ten new recovery measurements, new
             control limits should be calculated using only the most
             recent 20-30 data points.  These calculated control limits
             should never exceed those established in Sect. 10.3.2.

     10.6.3  It is  recommended that the laboratory periodically
             determine and document its detection limit capabilities for
             analytes of interest.

                                374

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      10.6.4  At least quarterly, analyze a QC sample from an outside
             source.

      10.6.5  Laboratories are encouraged to participate in external
             performance evaluation studies such as the laboratory
             certification programs offered by many states or the
             studies conducted by U.S. EPA.  Performance evaluation
             studies serve as independent checks on the analyst's
             performance.

10.7  ASSESSING ANALYTE RECOVERY - LABORATORY FORTIFIED SAMPLE MATRIX

      10.7.1  The laboratory must add a known concentration to a minimum
             of 5% of the routine samples or one sample concentration
             per set, whichever is greater.  The concentration should
             not be less then the background concentration of the sample
             selected for fortification.  Ideally, the concentration
             should be the same as that used for the laboratory
             fortified blank (Sect.  10.6).  Over time, samples from all
             routine sample sources should be fortified.

      10.7.2  Calculate the percent recovery, P of the concentration for
             each analyte, after correcting the analytical result, X,
             from the fortified sample for the background concentration,
             b, measured in the unfortified sample, i.e.,:

             P = 100 (X - b) / fortifying concentration,

             and compare these values to control limits appropriate for
             reagent water data collected in the same fashion.   If the
             analyzed unfortified sample is found to contain NO
             background concentrations, and the added concentrations are
             those specified in Sect.  10.7, then the appropriate control
             limits would be the acceptance limits in Sect.  10.7.   If,
             on the other hand, the  analyzed unfortified  sample is found
             to contain background concentration, b, estimate the
             standard deviation at the background concentration, sb,
             using regressions or comparable background data and,
             similarly,  estimate the mean,  Xa  and  standard deviation,
             sa,  of analytical  results  at  the'total  concentration  after
             fortifying.   Then the appropriate  percentage control  limits
             would be P ± 3sp,  where:

             P = 100 X  / (b + fortifying concentration)


                                         1/2
                                2      2
             and s   = 100    (s   + s  )    /fortifying concentration
                  P            a     b
                                375

-------
             would be (1.6 /ig/L minus 1.0 /ig/L)/l /ig/L or 60%.  This
             calculated P is compared to control limits derived from
             prior reagent water data.  Assume it is known that analysis
             of an interference free sample at 1 /ig/L yields an_s of
             0.12 /zg/L and similar analysis at 2.0 /ig/L yields X and s
             of 2.01 /ig/L and 0.20 /ig/L, respectively.  The appropriate
             limits to judge the reasonableness of the percent recovery,
             60%, obtained on the fortified matrix sample is computed as
             fol1ows:

             [100 (2.01 /ig/L) / 2.0 /ig/L]

                                                      1/2
             ± 3 (100)  [(0.12 "/ig/L)2 + (0.20 /ig/L)2]    / 1.0  /ig/L  =

             100.5% ± 300 (0.233) =

             100.5% ± 70% or 30% to 170% recovery of the added analyte.

      10.7.3  If the recovery of any such analyte falls outside the
             designated range, and the laboratory performance for that
             analyte is shown to be in control  (Sect. 10.6), the
             recovery problem encountered with the dosed sample is
             judged to be matrix related, not system related.  The
             result for that analyte in the unfortified  sample is
             labeled suspect/matrix to inform the data user that the
             results are suspect due to matrix effects.

10.8  ASSESSING  INSTRUMENT SYSTEM -  LABORATORY PERFORMANCE CHECK SAMPLE  -
      Instrument  performance  should  be monitored  on  a  daily  basis by
      analysis of the LPC sample.  The LPC  sample contains compounds
      designed to indicate appropriate instrument sensitivity, column
      performance (primary column) and chromatographic performance.   LPC
      sample  components and performance  criteria are listed  in Table 3.
      Inability  to demonstrate  acceptable instrument performance
      indicates  the  need for  revaluation of  the instrument  system.   The
      sensitivity requirements  are set based  on  the  EDLs  published  in
      this  method.   If laboratory EDLs differ from those  listed  in  this
      method, concentrations  of the  instrument QC standard compounds must
      be  adjusted to be compatible with  the laboratory EDLs.

10.9  The laboratory may adopt  additional quality control  practices  for
      use with this  method.   The  specific practices  that  are most
      productive  depend upon  the  needs of the laboratory  and the nature
      of  the  samples.  For example,  field or  laboratory  duplicates  may be
      analyzed to assess the  precision of the environmental  measurements
      or  field reagent blanks may be used to  assess  contamination of
      samples under  site conditions,  transportation  and  storage.
                                 376

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11.   PROCEDURE

     11.1  PH ADJUSTMENT AND  FILTRATION

           11.1.1  Add preservative to any samples not previously preserved
                  (Sect. 8).  Adjust the pH of the sample or standard to pH 3
                  ± 0.2 by adding 1.5 ml of 2.5 M monochloroacetic acid
                  buffer to each 50 ml of sample.  This step should not be
                  necessary if sample pH was adjusted during sample
                  collection as a preservation precaution.  Fill a 50-mL
                  volumetric flask to the mark with the sample.  Add 5 nl of
                  the internal standard fortification solution (if the
                  internal standard calibration procedure is being employed)
                  and mix by inverting the flask several times.

           11.1.2  Affix the three-way valve to a 10-mL syringe.  Place a
                  clean filter in the filter holder and affix the filter
                  holder and the 7- to 10-cm syringe needle to the syringe
                  valve.   Rinse the needle and syringe with reagent water.
                  Prewet the filter by passing 5 ml of reagent water through
                  the filter.  Empty the syringe and check for leaks.   Draw
                  10 ml of sample into the syringe and expel  through the
                  filter.   Draw another 10 ml of sample into the syringe
                  expel  through the filter,  and collect the last 5 mL  for
                  analysis.   Rinse the syringe with reagent water.   Discard
                  the filter.

     11.2  LIQUID CHROMATOGRAPHY

          11.2.1  Sect.  6.6  summarizes the recommended operating conditions
                  for the  liquid  chromatograph.   Table 1 lists  retention
                  times  observed  using this  method.   Other HPLC columns,
                  chromatographic conditions,  or detectors may  be used  if the
                  requirements of Sect.  10.4 are met.

          11.2.2  Calibrate  the system daily as  described  in  Sect.  10.   The
                  standards  and samples  must be  in  pH  3  buffered  water.

          11.2.3  Inject 400 fil of the  sample.   Record the volume injected
                  and  the  resulting peak size  in  area  units.

          11.2.4  If the response  for the  peak exceeds the working  range  of
                  the  system,  dilute the  sample with pH  3  buffered  reagent
                  water and reanalyze.

    11.3  IDENTIFICATION OF  ANALYTES

          11.3.1  Identify a sample component by comparison of  its  retention
                  time to the  retention time of a reference chromatogram.   If
                  the  retention time of an unknown compound corresponds,
                  within limits, to the retention time of  a standard
                  compound, then identification is considered positive.

                                    377

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           11.3.2  The width of the retention time window used to make
                  identifications should be based upon measurements of actual
                  retention time variations of standards over the course of a
                  day.  Three times the standard deviation of a retention
                  time can be used to calculate a suggested window size for a
                  compound.  However, the experience of the analyst should
                  weigh heavily in the interpretation of chromatograms.

           11.3.3  Identification requires expert judgement when sample
                  components are not resolved chromatographically.  When
                  peaks obviously represent more than one sample component
                  (i.e.,  broadened peak with shoulder(s) or valley between
                  two or  more maxima), or any time doubt exists over the
                  identification of a peak on a chromatogram, appropriate
                  alternate techniques, to help confirm peak identification,
                  need to be employed.  For example, more positive
                  identification may be made by the use of an alternative
                  detector which operates on a chemical/physical principle
                  different from that originally used; e.g., mass
                  spectrometry, or the use of a second chromatography column.
                  A suggested alternative column is described in Sect. 6.6.3.

12.  CALCULATIONS

     Determine the  concentration of individual compounds in the sample using
     the following  equation:


           Cx  -   Ax   -   's
                   A.   .    RF
                    s
           where:  Cx =  analyte concentration  in micrograms per liter;
                   Ax =  response of the sample analyte;
                   A. -  response of the standard (either  internal or
                         external), in units consistent with those used
                         for the analyte response;
                   RF  =  response  factor  (with  an external  standard,  RF  =  1,
                         because the standard is the same compound as the
                         measured analyte);

                   Qs =  concentration of  internal standard present or
                         concentration of external standard that produced As,
                         in micrograms per liter.

13.  PRECISION AND ACCURACY

     13.1  In a single laboratory, analyte recoveries from reagent water were
           determined at five concentration levels.  Results were used to
           determine analyte EDLs and demonstrate method range.(1)  Analyte
                                     378

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           recoveries and standard deviation about the percent recoveries at
           one concentration are given in Table 2.

     13.2  In a single laboratory, analyte recoveries from two standard
           synthetic ground waters were determined at one concentration level
           Results were used to demonstrate applicability of the method to
           different ground water matrices.(1)  Analyte recoveries from the
           two synthetic matrices are given in Table 2.

14.  REFERENCES

     1.    National  Pesticide Survey Method No.  5.,  "Measurement of N-
           Methylcarbamoyloximes and N-Methylcarbamates in Groundwater by HPL
           with Post Column Derivatization,"

     2.    Moye,  H.A.,  S.J.  Sherrer, and  P. A.  St. John,  "Dynamic Labeling of
           Pesticides for High Performance Liquid Chromatography:  Detection
           of N-Methylcarbamates and o-Phthalaldehyde," Anal.  Lett.  10_,  1049,
           A J / / •  '

     3.    ASTM Annual  Book of Standards,  Part  11, Volume 11.02,  D3694-82,
           "Standard Practice for Preparation  of Sample Containers  and for
           Preservation," American Society for Testing  and Materials,
           Philadelphia,  PA,  p.  86,  1986.

     4.    "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.

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

     6.    "Safety in Academic Chemistry Laboratories," American  Chemical
          Society Publication, Committee  on Chemical Safety,  3rd Edition,
           * «* / 5* »

     7.   Foerst, D. L.  and H. A. Moye, "Aldicarb in Drinking Water via
          Direct Aqueous  Injection HPLC with Post Column Derivatization,"
          Proceedings of the 12th annual AWWA Water Quality Technology
          Conference, 1984.

     8.    Hill, K. M., R.H. Hollowell, and L. A. DalCortevo,  "Determination
          of N-Methylcarbamate Pesticides in Well Water by Liquid
          Chromatography and Post Column Fluorescence Derivatization,"
          Anal. Chem. £6, 2465 (1984).

     9.    ASTM Annual Book of Standards,  Part 11, Volume 11.01,  D3370-82,
          "Standard Practice for Sampling Water," American Society for
          Testing and Materials, Philadelphia, PA, p. 130, 1986.


                                     379

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           TABLE 1.  RETENTION TIMES  FOR METHOD ANALYTES
                                     Retention Time(a)
                         PHmarv<1)   Alternative*2*      Alternative0"
Aldicarb sulfoxide
Aldicarb sirtfone
Oxamyl
Methomyl
3-Hydroxycarbofuran
Aldicarb
Baygon
Carbofuran
Carbaryl
Methiocarb
BDMC
6.80
7.77
8.20
8.94
13.65
16.35
18.86
19.17
20.29
24.74
25.28
15.0
15.2
17.4
18.4
23.3
27.0
29.3
29.6
30.8
34.9
35.5
17.5
12.2
14.6
14.8
19
21.4
24.4
23.4
25.4
28.6

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