United States
    Environmental Protection
    Agency
METHOD 524.4    MEASUREMENT OF PURGEABLE
                  ORGANIC COMPOUNDS IN WATER
                  BY GAS CHROMATOGRAPHY/MASS
                  SPECTROMETRY USING NITROGEN
                  PURGE GAS

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Questions concerning this document should be addressed to:

Steven C. Wendelken, PhD
U.S. EPA, OGWDW/SRMD/TSC, 26 W. Martin Luther King Dr. Cincinnati, OH 45219
Phone: (513)569-7491
wendelken.steve@epa.gov
Office of Water (MS-140)
EPA815-R-13-002
May 2013

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                                         Foreword

This method was prepared under the direction of David J. Munch and Steven C. Wendelken, PhD of the
Technical Support Center within the U.S. EPA Office of Water.  Shaw Environmental Inc. provided
support under EPA contracts EP-C-06-03 land EP-C-12-013. The following are acknowledged for their
support in development of this method:

Tom Hartlein, Tekmar (Teledyne Technologies,  Inc.)
Roger Bardsley, Tekmar (Teledyne Technologies, Inc.)
Laura Chambers, OI Analytical
John George, Bruker Corporation
Yongtao Li, Underwriters Laboratories, Inc.
Bill Davis, Underwriters Laboratories, Inc.
Dr. Andrew Eaton, Eurofins Eaton Analtyical
Kipp Phelan, Eurofins Eaton Analytical

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                                       METHOD 524.4

     MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY GAS
     CHROMATOGRAPHY/MASS SPECTROMETRY USING NITROGEN PURGE GAS
1.   SCOPE AND APPLICATION

    1.1  This is a gas chromatography/mass spectrometry (GC/MS) method for the determination of
         purgeable organic compounds in finished drinking waters.  Discontinuous scanning modes
         such as selected ion monitoring (SIM) and selected ion storage (SIS) are permitted for
         determining selected analytes that are monitored at levels too low for the full scan detection
         mode.  Precision and accuracy data have been generated for the method analytes in reagent
         water, drinking water from a groundwater source and drinking water from a surface water
         source.  The single laboratory Lowest Concentration Minimum Reporting Level (LCMRL)
         has also been determined in reagent water.  The following compounds can be determined
         using this method:

                                              Chemical Abstract Services Registry
            Analvte                                   Number (CASRN)
            1,1,1,2-tetrachloroethane                         63 0-20-6
            1,1,1-trichloroethane                              71-55-6
            1,1,2,2-tetrachloroethane                          79-34-5
            1,1,2-trichloroethane                              79-00-5
            1,1-dichloroethane                                75-34-3
            1,1-dichloroethene                                75-35-4
            1,1-dichloropropene                             563-58-6
            1,2,3-trichlorobenzene                            87-61-6
            1,2,3-trichloropropane                            96-18-4
            1,2,4-trichlorobenzene                           120-82-1
            1,2,4-trimethylbenzene                            95-63-6
            l,2-dibromo-3-chloropropane                      96-12-8
            1,2-dibromoethane                               106-93-4
            1,2-dichlorobenzene                              95-50-1
            1,2-dichloroethane                               107-06-2
            1,2-dichloropropane                              78-87-5
            1,3,5-trimethylbenzene                           108-67-8
            1,3-butadiene                                   106-99-0
            1,3-dichlorobenzene                             541-73-1
            1,3-dichloropropane                             142-28-9
            1,4-dichlorobenzene                             106-46-7
            1-chlorobutane                                  109-69-3
            2-chlorotoluene                                  95-49-8
            4-chlorotoluene                                 106-43-4
                                           524.4-1

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Analyte
4-i sopropyl toluene
allyl chloride
benzene
bromobenzene
bromochloromethane
bromodichloromethane
bromoform
bromomethane
carbon disulfide
carbon tetrachloride
chlorobenzene
chlorodifluoromethane
chloroform
chloromethane
cis-l,2-dichloroethene
cis-l,3-dichloropropene
dibromochloromethane
dibromomethane
di chlorodifluoromethane
di ethyl ether
dii sopropyl ether (DIPE)
ethyl methacrylate
ethylbenzene
hexachl orobutadi ene
hexachloroethane
isopropylbenzene
methyl acetate
methyl iodide
methylene chloride
methyl-t-butyl ether (MtBE)
m-xylene
naphthalene
n-butylbenzene
n-propylbenzene
o-xylene
pentachloroethane
p-xylene
sec-butylbenzene
styrene
t-amyl ethyl ether (TAEE)
Chemical Abstract Services Registry
         Number (CASRN)
              99-87-6
             107-05-1
              71-43-2
             108-86-1
              74-97-5
              75-27-4
              75-25-2
              74-83-9
              75-15-0
              56-23-5
             108-90-7
              75-45-6
              67-66-3
              74-87-3
             156-59-2
            10061-01-5
             124-48-1
              74-95-3
              75-71-8
              60-29-7
             108-20-3
              97-63-2
             100-41-4
              87-68-3
              67-72-1
              98-82-8
              79-20-9
              74-88-4
              75-09-2
             1634-04-4
             108-38-3
              91-20-3
             104-51-8
             103-65-1
              95-47-6
              76-01-7
             106-42-3
             135-98-8
             100-42-5
             919-94-8
                               524.4-2

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                                          Chemical Abstract Services Registry
       Analvte                                    Number (CASRN)
       t-amyl methyl ether (TAME)                      994-05-8
       t-butyl alcohol (TEA)                             75-65-0
       t-butyl ethyl ether (ETBE)                        637-92-3
       t-butylbenzene                                   98-06-6
       tetrachloroethene                                127-18-4
       tetrahydrofuran                                  109-99-9
       toluene                                         108-88-3
       trans- 1,2-dichloroethene                          156-60-5
       trans-1,3 -dichloropropene                       10061 -02-6
       trichloroethene                                   79-01-6
       trichlorofluoromethane                            75-69-4
       vinyl chloride                                    75-01-4

1.2   The ranges for purge-and-trap parameters specified in Section 9.1 are applicable to the use of
     nitrogen purge gas; helium may not be used.  The mass spectrometry conditions described in
     this method were developed using a gas chromatograph (GC) interfaced to a quadrupole mass
     spectrometer (MS).

1.3   The single laboratory LCMRL is the lowest spiking concentration such that the probability of
     spike recovery in the 50% to 150% range is at least 99%. Single laboratory LCMRLs for the
     analytes in this method ranged from 0.10 to 0.62 microgram per liter (|ig/L) in the full scan
     mode (Table 6).  Single laboratory LCMRLs  were also determined for selected analytes in the
     selected ion monitoring (SUV!) mode (Table 10). The procedure used to determine the
     LCMRL is described elsewhere.1

1.4   Laboratories using this method are not required to determine LCMRLs, but they must
     demonstrate that the minimum reporting level (MRL) for each analyte meets the requirements
     described in Section 9.2.4.

1.5   Detection limit (DL) is defined as the statistically calculated minimum concentration that can
     be measured with 99% confidence that the reported value is greater than zero.2 The DL is
     dependent on sample matrix, fortification concentration and instrument performance. Deter-
     mining the DL for analytes in this method is optional (Sect. 9.2.6). DLs for method analytes
     fortified into reagent water ranged from 0.026 to 0.18 |ig/L in the full scan mode.  These
     values are presented in Table 6. DLs were also determined for selected analytes in SIM mode
     (Table 10).

1.6   This method is intended for use by analysts skilled in the technique of purge-and-trap
     concentration, the operation  of GC/MS instrumentation and the interpretation of the
     associated data.

1.7   METHOD FLEXIBILITY - To accommodate technological  advances in analytical
     instrumentation and techniques, the laboratory is permitted to modify purge-and-trap
     parameters and the GC/MS conditions.  Because the purge-and-trap technique has a
     significant number of analyst-chosen parameters and because it employs a procedural
                                       524.4-3

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         calibration, the authors have determined an acceptable range of purge-and-trap conditions that
         may be used (Sect. 9.1) and a means by which to evaluate method modifications (Sect. 9.4).
         Changes may not be made to sample collection and preservation (Sect. 8) or to the
         quality control (QC) requirements (Sect. 9). Modifications that are introduced solely in the
         interest of reducing cost or sample processing time, but result in poorer method performance,
         may not be used.  The option to operate the MS in SIM or SIS mode is restricted to analytes
         that cannot be effectively analyzed in full scan mode, e.g., 1,2-dibromoethane and 1,2-
         dibromo-3-chloropropane. The SIM detection mode should not be used to enhance analyte
         signal for instrumentation that is not properly optimized and maintained. Compliance
         monitoring for trihalomethanes (THMs) must be  conducted in the full scan detection mode.
         In all cases where allowed method modifications are made, the analyst must perform the
         procedures outlined in the Initial Demonstration of Capability (IDC, Sect. 9.2), verify that all
         QC acceptance criteria in this method (Tables 12 and 13) are met and verify method
         performance in real sample matrices (Sect. 9.4.4).

         NOTE: This description of method flexibility is a brief summary. Additional specific detail
         is provided throughout the method, which supersedes the above general guidance.

2.  SUMMARY OF METHOD

    Headspace-free samples are collected in amber, glass vials with polytetrafluoroethylene (PTFE)-
    faced septa.  Samples are dechlorinated with ascorbic acid and the pH is adjusted with maleic acid.
    A 5.0-milliliter (mL) aliquot of the sample is transferred to a glass sparging vessel along with
    appropriate amounts of internal standard and quality control compounds. The method analytes are
    purged from the water using nitrogen and trapped on a sorbent material. After purging, the trap
    may be dry purged for a short period to remove water.  The trap is then heated and backflushed with
    GC carrier gas to transfer the analytes directly into the  gas chromatographic inlet.  The inlet is
    operated in the split mode in order to achieve the desired desorb flow rates and further reduce water
    transmission. Analytes are transferred onto a capillary GC column, which is temperature
    programmed to optimize the separation of method analytes. Compounds eluting from the GC are
    directed into a mass spectrometer for detection and quantitation.  The method analytes are identified
    by comparing the acquired mass spectra and retention times to reference spectra and retention
    times.  The concentration of each analyte is calculated  using the internal standard technique and
    response curves obtained via procedural calibration (Sect.  3.18).

3.  DEFINITIONS

    3.1   ANALYSIS BATCH - A sequence of samples, analyzed within a 24-hour period, including
         no more than 20 field samples. Each Analysis Batch must also include all required QC
         samples, which do not contribute to the maximum field sample total of 20. The required  QC
         samples include:

             Laboratory Reagent Blank (LRB),
             Continuing Calibration Check (CCC) Standards,
             Laboratory Fortified Sample Matrix (LFSM) and
             Laboratory Fortified Sample Matrix Duplicate or Field Duplicate (LFSMD or FD).
                                            524.4-4

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3.2  CALIBRATION STANDARD - An aqueous solution of the method analytes prepared from
     the Primary Dilution Standard solution. The calibration standard solutions are used to
     calibrate the instrument response with respect to analyte concentration.

3.3  CONTINUING CALIBRATION CHECK (CCC) - A calibration standard containing the
     method analytes, internal standards and surrogate analytes, which is analyzed periodically to
     verify the accuracy of the existing calibration.

3.4  DESORB FLOW RATE - The rate at which gas  is passed through the sorbent trap during the
     desorb cycle.  The desorb flow rate is approximately equal to the total flow rate through the
     GC inlet (mL/min).

3.5  DETECTION LIMIT (DL) - The minimum concentration of an analyte that can be identified,
     measured and reported with 99% confidence that the analyte concentration is greater than
     zero.  This is a statistical determination (Sect. 9.2.6) and accurate quantitation is not expected
     at this level.

3.6  DRY PURGE VOLUME - The total volume of purge gas (mL) bypassing the sparging vessel
     and passing through the sorbent trap during the dry purge cycle (used as a moisture control
     measure).

3.7  FIELD DUPLICATE (FD) - Separate  samples collected at the same time, shipped and stored
     under identical conditions. Method precision, including the contribution from sample
     collection procedures, is estimated from the analysis of FDs. For the purposes of this method,
     FDs are necessary to conduct repeat analyses if the original field sample is lost or to conduct
     repeat analyses in the case of QC failures associated with the analysis of the original field
     sample.  FDs are used to prepare Laboratory Fortified Sample Matrix (Sect. 3.11) and
     Laboratory Fortified Sample Matrix Duplicate (Sect. 3.12) QC samples.

3.8  FIELD REAGENT BLANK (FRB) - An aliquot  of reagent water that is placed in a sample
     container in the laboratory and treated as a sample in all respects, including shipment to the
     sampling site, exposure to sampling site conditions, storage,  preservation and all  analytical
     procedures. The purpose of the FRB is to determine if method analytes or other interferences
     are introduced into the  samples during  transport and storage.

3.9  INTERNAL STANDARD (IS) - A pure compound added to all standard solutions, field
     samples and QC samples in a known amount. Each internal  standard is assigned to a specific
     analyte or multiple analytes and is used to measure relative response.

3.10 LABORATORY FORTIFIED BLANK (LFB) -  An aliquot of reagent water to which known
     quantities of the method analytes are added.  The LFB is analyzed in the same manner as a
     sample, including the preservation procedures in  Section 8. The LFB is used during the Initial
     Demonstration of Capability to verify method performance for precision and accuracy.

3.11 LABORATORY FORTIFIED SAMPLE MATRIX (LFSM)  - A FD to which known
     quantities of the method analytes are added.  The LFSM is processed and analyzed as a
     sample and its purpose is to determine  whether the sample matrix contributes bias to the
     analytical results.  For this method, separate field samples are required for preparing fortified
     matrix so that sampling error is included in the accuracy estimate.
                                      524.4-5

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3.12 LABORATORY FORTIFIED SAMPLE MATRIX DUPLICATE (LFSMD) - A second FD,
     of the same sample used to prepare the LFSM, which is fortified identically to the LFSM.
     The LFSMD is used instead of the FD to assess method precision and accuracy when the
     occurrence of the method analytes is infrequent. For this method,  separate field samples are
     required for preparing fortified matrix so that sampling error is included in the precision
     estimate.

3.13 LABORATORY REAGENT BLANK (LRB) - An aliquot of reagent water containing the
     preservatives, internal standards and surrogate analytes. The LRB is used to determine if the
     method analytes or interferences are introduced from the laboratory environment, the reagents
     or glassware. The LRB is also used to test for cross contamination in the purge-and-trap
     system.

3.14 LOWEST CONCENTRATION MINIMUM REPORTING LEVEL (LCMRL) - The single
     laboratory LCMRL is the lowest spiking concentration such that the probability of spike
     recovery in the 50% to 150% range is at least 99%.l

3.15 MATERIAL SAFETY DATA SHEETS (MSDS) - Written information provided by vendors
     concerning a chemical's toxicity, health hazards, physical  properties, fire and reactivity data,
     storage instructions, spill response procedures and handling precautions.

3.16 MINIMUM REPORTING LEVEL (MRL) - The minimum concentration that can be reported
     by a laboratory as a quantified value for the method analyte in a sample following analysis.
     This concentration must meet the  criteria defined in Section 9.2.4 and must be no lower than
     the concentration of the lowest calibration standard for each method analyte.

3.17 PRIMARY DILUTION  STANDARD (PDS) - A solution containing the method analytes (or
     internal standards and surrogate analytes) prepared in the laboratory from Stock Standard
     Solutions and diluted as needed to prepare calibration standards and sample fortification
     solutions.

3.18 PROCEDURAL CALIBRATION - A calibration technique in which calibration standards are
     processed through the entire method, including sample preparation, addition of preservatives,
     extraction and concentration.

3.19 PURGE FLOW RATE - The rate (mL/min) that the purge gas flows through the sparging
     vessel during the purge cycle.

3.20 PURGE VOLUME - The total volume of purge gas (mL) that flows through the sparging
     vessel during the purge cycle.

3.21 QUALITY CONTROL SAMPLE (QCS) - A solution containing the method analytes at a
     known concentration that is obtained from a source external to the laboratory and different
     from the source of calibration standards. The purpose of the QCS is to verify the accuracy of
     the primary calibration standards.

3.22 REAGENT WATER - Purified water that does not contain any measurable quantity of the
     method analytes or interfering compounds at or above l/2 the MRL.
                                      524.4-6

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    3.23 STOCK STANDARD SOLUTION (SSS) - A concentrated solution containing one or more
         of the method analytes that is prepared in the laboratory using assayed reference materials or
         purchased from a reputable commercial source, so that the concentration and purity of
         analytes are traceable to certificates of analysis.

    3.24 SURROGATE ANALYTE - A pure analyte which is extremely unlikely to be found in any
         sample and which is added to a sample aliquot in a known amount before analysis.  Surrogates
         are measured with the same procedures used to measure other sample components.  Because
         surrogates are present in every sample, they provide a means of assessing method
         performance for a specific purge-and-trap analysis cycle.

4.   INTERFERENCES

    4.1  SAMPLE CONTAINERS, SHIPPING AND STORAGE - Volatile organic compounds
         (VOCs) present in ambient air, shipping containers and in the laboratory environment may
         permeate the PTFE-lined septa of the sample vials or be present at high concentrations in the
         headspace of the vial (especially if the vials were prepared in a laboratory). Contamination
         from these sources is evaluated by analyzing FRBs as described in Section 9.3.9.

    4.2  PURGE-AND-TRAP SYSTEM - Commercially available purge-and-trap concentrators and
         autosamplers have complex sample paths that are subject to cross contamination, which is
         commonly referred to as "carryover." Carryover is controlled by minimizing the transfer line
         length from the autosampler to the sparging vessel and optimizing the bake cycle and rinse
         cycle parameters. The potential for carryover in the purge-and-trap system is evaluated during
         the Initial Demonstration of Capability by analyzing the highest concentration calibration
         standard followed by a LRB.

    4.3  REAGENTS - All laboratory reagents must be routinely demonstrated to be free of
         interferences under the conditions  of the analysis.  This may be accomplished by analyzing
         LRBs and meeting the acceptance  criterion as described in Section 9.3.1.

         4.3.1    REAGENT WATER - Analysts may observe common laboratory contaminants, such
                 as methylene chloride, in reagent water.  Boiling and/or sparging reagent water with
                 nitrogen is recommended. If possible, prepare aqueous standards  and blanks in a
                 laboratory environment isolated from ambient sources of VOCs.

         4.3.2    METHANOL - Traces of ketones, methylene chloride and other organic solvents
                 could be present in methanol. Use purge-and-trap-grade methanol with this method.

         4.3.3    PRESERVATION REAGENTS - The potential exists for trace-level organic
                 contaminants in the preservation reagents.  Interferences from these sources must be
                 monitored by analysis of LRBs when new lots of reagents are acquired.

         4.3.4    SORBENT MATERIALS - Sorbent traps must be carefully evaluated because some
                 traps, when heated, have been reported to produce small amounts  of VOCs,
                 particularly with extended use. For example, toluene may be detected  the first time a
                 trap is desorbed during a work shift. For this reason, a short bake cycle prior to
                 beginning an analysis sequence is recommended. In addition, carbon-based traps,
                                           524.4-7

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                recommended for use with nitrogen purge by this method (Section 6.8.2), commonly
                produce chloromethane and bromomethane when heated.  This phenomenon is caused
                by the reaction of methanol with the adsorbent materials when the trap is heated in
                the desorb mode. The quantity of methanol used to prepare aqueous samples should
                be minimized and background levels of chloromethane and bromomethane should be
                carefully monitored in LRBs analyzed with each Analysis Batch.  Background levels
                may preclude quantitation of these two analytes in  SIM mode.

         4.3.5   PURGE GAS SUPPLY - Nitrogen used to purge samples is a potential source of
                contamination.  Trace VOCs in the purge gas, supply lines or the gas supply system
                (including the regulator) can concentrate on the sorbent trap.  High-purity gas
                supplies and high-purity gas regulators are recommended to minimize contamination
                from these sources. Purge gas filters should be regenerated or replaced at the
                intervals specified by the manufacturers.

    4.4  MATRIX INTERFERENCES - Matrix interferences are caused by contaminants that are
         present in the sample. The extent of matrix interferences will vary considerably from source
         to source depending upon the nature of the water.  The analysis of LFSM (Sect.  9.3.7)
         provides evidence for the presence (or absence) of matrix effects.

5.   SAFETY

   5.1   The toxicity or carcinogenicity of each reagent 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 an awareness
         of OSHA regulations regarding safe handling of chemicals  used in this method.3 A reference
         file of MSDSs should be made available to all personnel involved in the analysis.

   5.2   Pure standard materials and Stock Standard Solutions of the method compounds should be
         handled with suitable personal  protection equipment.4

6.   EQUIPMENT AND SUPPLIES

    References to specific brands or catalog numbers are included as examples only and do not imply
    endorsement of the product.  These references do not preclude the use of other vendors or supplies.

    6.1  SAMPLE CONTAINERS - Clean, amber volatile organic analysis (VGA) vials fitted with
         PTFE-faced silicone septa and  polypropylene screw caps (I-Chem Cat. No. S146-0040 or
         equivalent).

    6.2  MICRO SYRINGES - Suggested sizes include 2.0, 5.0, 10 and 25 |iL.

    6.3  PURGE-AND-TRAP SYRINGES - 5-mL glass syringes with PTFE Luer-Lok fitting
         (Hamilton Model No. 1005 TLL or equivalent) for manual loading of samples into a sparging
         vessel.

    6.4  SYRINGE VALVE - two-position syringe valves with Luer ends (Supelco Cat. No. 20926 or
         equivalent) for use in sealing purge-and-trap syringes (Sect. 6.3).

                                          524.4-8

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6.5  VOLUMETRIC FLASKS - Class A, suggested sizes include 50, 100 and 200 mL for
     preparation of calibration standards.

6.6  ANALYTICAL BALANCE - Capable of weighing to the nearest 0.0001 gram (g).

6.7  MICRO-REACTION VESSEL - 0.3-, 1.0-, 2.0-, 5.0-mL sizes (Supelco CatNos. 33291,
     33293, 33295, 33299 or equivalent) equipped with Mininert Valves [Supelco Cat No. 33301
     (15 millimeter (mm) for 0.3-, 1.0- and 2.0-mL vials) and Cat No. 33303 (20 mm for 5.0-mL
     vials)]. These vials are recommended for storage of Stock Standard Solutions and Primary
     Dilution Standards (PDS) prepared in methanol.

6.8  PURGE-AND-TRAP SYSTEM - Any purge-and-trap unit that is capable of being
     electronically interfaced to the GC and that is capable of meeting the method QC
     requirements outlined in Section 9 is permitted. The concentrator(s) may be equipped with an
     autosampler.  Moisture control modules are permitted but not required.

     6.8.1   SPARGING VESSEL - Instruments must be equipped with a sparging vessel
            specifically designed for purging a 5-mL sample volume.  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 less than 3 mm at the origin.

            NOTE:  Larger sparging vessels are not allowed. While the larger sample volume
            could result in the transfer of more analyte to the trap, purging efficiency decreases
            unless the purge volume is increased proportionally. While the procedural calibration
            technique corrects for this, lower purging efficiency decreases method precision. In
            addition, larger purge volumes could result in the transfer of more water vapor to the
            trap, placing increased demand on moisture control strategies.

     6.8.2   SORBENT TRAP - Purge-and-trap manufacturers typically recommend specific
            sorbent traps for use with their instruments. Any trap design is acceptable provided
            the data acquired meet all QC criteria described in Section 9.

            During method development studies using nitrogen purge, traps containing Tenax,
            silica gel and coconut charcoal in series yielded lower recoveries for most of the
            method analytes when compared directly to the recoveries obtained using a helium
            purge. A trap containing Tenax, silica gel and  carbon molecular sieve (CMS)
            exhibited similar poor performance. Thus, traps containing Tenax, silica gel and
            coconut charcoal or Tenax, silica gel and CMS may not be used in this method.
            Traps containing synthetic carbon adsorbent media (Supelco Vocarb 3000 or
            equivalent) are recommended for use with this method.

     6.8.3   TRANSFER LINE - Silcosteel or equivalent  heated transfer line used to transfer the
            desorbed analytes from the purge-and-trap concentrator to the injection port of the
            GC.

     6.8.4   SAMPLE HEATER - A sparging vessel heater is optional. Resistance or infrared
            heaters may be used.
                                       524.4-9

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     6.8.5   REFRIGERATED AUTOSAMPLER - Vial autosamplers must be capable of
            maintaining samples at a temperature of 10 C or lower. Verify the temperature of
            field samples placed in the autosampler using an external thermocouple or
            thermometer (inserted into a vial containing water) during the IDC and at least
            quarterly.  This temperature must not be altered after collecting the initial calibration
            because it may change analyte purging efficiencies.

     6.8.6   STANDARD ADDITION MODULE - Automated device incorporated into vial
            autosamplers capable of fortifying internal standards and surrogate analytes directly
            into the sparging vessel. A standard addition module is recommended when vial
            autosamplers are used in the method.

     6.8.7   TANDEM PURGE-AND-TRAP OPERATION - A technique allowing use of two
            purge-and-trap concentrators configured in tandem. The IDC procedure (Sect. 9.2)
            must be conducted for each concentrator. In addition, this  option requires separate
            QC samples for each sample path (Sect. 9.3), separate calibrations (Sect. 10) and the
            use of a marker compound (Sect. 10, Note) to uniquely identify the sample path.

6.9  GAS CHROMATOGRAPHY MASS  SPECTROMETRY SYSTEM/DATA SYSTEM
     (GC/MS/DS)

     6.9.1   GC INJECTOR AND OVEN - The GC must be capable of temperature programming
            and must be equipped with a standard split/splitless injector and a flow controller that
            is compatible with purge-and-trap analysis. In this configuration, the purge-and-trap
            effluent is plumbed directly to the carrier gas inlet line of a split/splitless injection
            port.  The injection port is operated in split mode to achieve the desired desorb flow
            rate and reduce water transmission. A deactivated glass liner (Restek Cat. No. 20972
            or equivalent) is recommended to minimize dead volume and active sites within the
            GC inlet.

     6.9.2   FUSED SILICA CAPILLARY GC COLUMN - Laboratories must use a column
            specifically designed for analysis of volatile  organic compounds by purge-and-trap.
            The column must have an i.d. of 0.32 mm or less to be compatible with operation in
            the  split mode (Sect. 6.9.1). The column must be capable of resolving the method
            analytes so that a unique quantitation ion is available for each analyte.

     6.9.3   GC/MS INTERFACE - The mass spectrometer must have sufficient vacuum
            pumping capacity to allow the direct feed of the analytical  column to the ion source.

     6.9.4   MASS SPECTROMETER (MS) - The MS must be capable  of electron ionization
            (El) at a nominal energy of 70 electron volts (eV) and must be operated in the
            positive ion mode.  An ion-trap mass spectrometer, tuned to produce mass spectra
            that approximate standard, library spectra obtained under El  conditions, may be used.
            The instrument must be capable of obtaining at least  six scans during the elution of
            each chromatographic peak.  Seven to ten scans across chromatographic peaks are
            recommended.  The spectrometer must produce a mass spectrum that meets all
            criteria in Table 1 when 4-bromofluorobenzene (BFB) is introduced into the GC/MS
            (Sect. 10.1.1).

                                      524.4-10

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         6.9.5   DATA SYSTEM - 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 allow integration of the
                ion abundance of any specific ion between specified time or scan number limits. The
                software must also allow construction of linear or second-order regression calibration
                curves and calculation of concentrations using the internal standard technique.

7.  REAGENTS AND STANDARDS

   7. 1   REAGENTS AND SOLVENTS - Reagent grade or better chemicals must be used. Unless
         otherwise indicated, all reagents should conform to the specifications of the Committee on
         Analytical Reagents of the American Chemical Society (ACS), when such specifications are
         available.  Other grades may be used as long as the reagent is of sufficiently high purity to
         permit its use without negatively affecting data quality.

         7.1.1   HELIUM - Ultra High Purity (99.999%) or equivalent, for use as GC carrier gas.

         7. 1 .2   NITROGEN - Ultra High Purity (99.999%) or equivalent, for use as purge gas.

         7.1.3   REAGENT WATER - Purified water which does not contain  any measurable
                quantities of any method analytes or interfering compounds at or above /^ the MRL
                for each compound of interest.
7. 1 .4   METHANOL (CH3OH, CAS# 67-56-1) - Purge-and-trap grade, demonstrated to be
       free of analytes and interferences (Bu
       Analysis Cat. No. 232 or equivalent).
                free of analytes and interferences (Burdick & Jackson Brand for Purge-and-trap
         7.1.5   ASCORBIC ACID (C6H8O6, CAS# 50-81-7) - Dechlorinating agent, demonstrated to
                be free of analytes and interferences (Alfa Aesar Cat. No. A15613 or equivalent).

         7. 1.6   MALEIC ACID (C4H4O4, CAS# 110-16-7) - Used as a preservative and to lower pH
                for the purpose of preventing dehydrohalogenation of chlorinated analytes. High
                purity, demonstrated to be free of analytes and interferences (Sigma Cat. No. M0375
                or equivalent).

         7.1.7   SODIUM THIOSULFATE (Na2S2O3, CAS# 7772-98-7) - Optional dechlorinating
                agent when sampling only for THMs (Sigma Cat. No. 563188 or equivalent).

    7.2  STOCK STANDARD SOLUTIONS - Certified mixes of the 524.4 method analytes, the
         internal standards and the surrogate analytes are recommended.  Users may prepare stock
         standards of the liquid and solid analytes, if not available as certified solutions, following the
         guidance provided in this section. After opening the sealed ampoules, store commercial
         mixes in micro-reaction vials with Mininert caps (Sect. 6.7) at a temperature of -10 C or
         lower.  After transfer replace vendor-supplied stock solutions within one month.
                                          524.4-11

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    NOTE: Methyl iodide may degrade faster than other liquid analytes.  Monitor the area of this
    compound relative to the internal standard, 1, 4-difluorobenzene. Replace the stock standard
    if methyl iodide shows evidence of degradation.

    7.2.1  INTERNAL STANDARD STOCK SOLUTIONS (ISSS) (1000 to 2500 |ig/mL) -
           This method uses three internal standards: 1,4-difluorobenzene (CAS# 540-36-3),
           chlorobenzene-Js (CAS# 3114-55-4) and l,4-dichlorobenzene-J4 (CAS# 3855-82-1).

    7.2.2  SURROGATE STOCK STANDARDS (SURSS) (1000 to 2500 |ig/mL) - This
           method uses three surrogate analytes: methyl-t-butyl-ether-J3 (CAS# 29366-08-3),
           bromofluorobenzene (BFB) (CAS# 460-00-4) and l,2-dichlorobenzene-J4 (CAS#
           2199-69-1).

    7.2.3  ANALYTE STOCK STANDARD SOLUTIONS - Obtain the analytes listed in the
           table in Section 1.1 as certified mixes in methanol or as neat standards if necessary.

    7.2.4  PREPARATION INSTRUCTIONS FOR LIQUID ANALYTES - Prepare the stock
           standards individually at 10 mg/mL. Using an analytical balance, obtain a tare weight
           for a VOA vial containing 20-mL of purge-and-trap-grade methanol.  To achieve the
           10 mg/L nominal concentration, calculate the volume of the liquid analyte
           corresponding to 200 mg. Carefully measure this volume with a 250-jiL syringe and
           inject the entire quantity under the surface of the methanol.  Subtract the tare weight
           from the final weight to calculate the exact solution concentration. When a
           compound's purity is assayed to be 96 percent or greater, the weight can be used
           without correction to calculate the concentration of the stock standard.

    7.2.5  PREPARATION INSTRUCTIONS FOR SOLID ANALYTES - Prepare the stock
           standards individually at 10 mg/mL by weighing 200 mg of each solid analyte into a
           40-mL VOA vial and diluting to 20 mL with purge-and-trap-grade methanol.   For
           semi-solid and other difficult to transfer materials, insert the entire weigh boat into a
           VOA vial containing 20-mL of methanol.  If the measured mass of analyte is not
           exactly 200 mg, adjust the volume of methanol to achieve a nominal concentration of
           10 mg/mL.  When a compound's purity is assayed to be 96 percent or greater,  the
           weight can be used without correction to calculate the concentration of the stock
           standard.

    7.2.6  STORAGE OF INDIVIDUAL STOCK STANDARDS - Store stock standards in the
           VOA vials in which they were prepared.  Stock standard solutions of liquid and solid
           analytes prepared in-house are estimated to be stable for at least six months if stored at
           -10 C or colder.  However, such solutions may be stable for longer periods depending
           on the analyte. Laboratories must use accepted QC practices to determine when stock
           standards need to be replaced.

7.3  PRIMARY DILUTION STANDARDS  (PDS) - Prepare Primary Dilution Standards by
    combining and diluting appropriate volumes of the stock standards with purge-and-trap-grade
    methanol.

    7.3.1  INTERNAL STANDARD AND SURROGATE PRIMARY DILUTION
           STANDARD (IS/surrogate PDS) - Prepare a combined internal standard and
                                     524.4-12

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               surrogate PDS from the ISSS and SURSS. Field samples and calibration standards
               must contain the same concentration of internal standards and surrogates and the
               quantity of methanol added should be minimized.  Between one and 5 jiL per 5-mL
               sample is recommended.  An IS/surrogate PDS concentration that results in the
               aqueous concentration falling in the mid-range of the initial calibration, e.g., 5 |ig/L in
               full scan mode and 0.5 jig/L in SIM mode is recommended.  Store the IS/surrogate
               PDS in a glass vial with Teflon-lined septa at a temperature of-10 C or colder.
               However, if the autosampler has a sealed reservoir on the standard addition module
               IS/surrogate PDS may be held at room temperature for extended periods (several
               months).

        7.3.2   ANALYTE PRIMARY DILUTION STANDARD (analyte PDS) - The analyte PDS is
               used to prepare the calibration standards and to fortify LFBs, LFSMs and LFSMDs
               with the method analytes.  The analyte PDS is prepared by combining appropriate
               volumes of the analyte stock standard solutions to  achieve concentrations appropriate
               for preparing aqueous calibration standards and fortifying samples. Choose
               concentrations such that at least 2 jiL of the PDS is transferred to achieve the desired
               aqueous concentration in the standard or QC samples; however, minimize the volume
               of methanol used. Methanol reacts to produce chloromethane and bromomethane
               when traps containing synthetic-carbon adsorbent  materials are heated (Sect. 4.3.4).
               During method development, PDS solutions ranged in concentration from 10 |ig/mL to
               400 |ig/mL. Lower concentrations of the analyte PDS may be necessary when
               conducting analyses in SIM mode. Store analyte PDS solutions in micro-reaction vials
               with Mininert caps at a temperature of-10 C or colder. PDS solutions which contain
               gases must be replaced after one week; those which do not contain gases may be
               stored for up to one month.

   7.4  CALIBRATION STANDARDS - Prepare procedural calibration standards by diluting the
        analyte PDS into reagent water containing the method preservatives (Sect. 8.1). A constant
        concentration of each internal standard and surrogate analyte is added to each calibration
        standard, either manually or by use of an automated standard addition module (Sect. 6.8.6).
        The lowest concentration calibration standard must be at or below the MRL. Additionally,
        these calibration standards may be used as CCCs. The dilution factors for calibration
        standards used to collect method performance data in Section 17 are provided in the tables
        below.

        Typical concentrations for aqueous calibration standards used during method development in
        full scan mode
CALa Level
1
2
o
J
4
5
6
7
Analyte PDS Cone. (jig/mL)
10
10
100
100
400
400
400
Analyte PDS
Volume (uL)
5.0
10
2.0
5.0
2.5
5.0
10
Final CAL Std. Volume (L)
0.100
0.100
0.100
0.100
0.100
0.100
0.100
Final CAL Std. Cone.
(Hg/L)
0.50
1.0
2.0
5.0
10
20
40
CAL = calibration standard.
                                         524.4-13

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         Typical concentrations for aqueous calibration standards used during method development in
         SIM mode
CAL Level
1
2
3
4
5
6
7
Analyte PDS Cone. (jig/mL)
0.1
1.0
1.0
1.0
10
10
10
Analyte PDS
Volume QiL)
10
2.5
5.0
10
2.0
5.0
10
Final CAL Std. Volume (L)
0.100
0.100
0.100
0.100
0.100
0.100
0.100
Final CAL Std. Cone.
(ng/L)
10
25
50
100
200
500
1,000
     7.5  GC/MS TUNE CHECK SOLUTION, BFB (CAS# 460-00-4) - Use the IS/surrogate analyte
         PDS (Sect. 7.3.1).

8.   SAMPLE COLLECTION, PRESERVATION and STORAGE

    8.1  SAMPLE COLLECTION
         8.1.1
         8.1.2
         8.1.3
         8.1.4
Prior to shipment to the field, ascorbic acid and maleic acid must be added to each
sample bottle.  Cap the vials tightly to avoid spillage of the preservation reagents. If
using a 40-mL vial, add 25 mg of ascorbic acid and 200 mg of maleic acid. If other
collection volumes are used, adjust the amount of the preservation reagents so that the
final concentrations of ascorbic acid and maleic acid in the sample containers are
0.625 g/L and 5 g/L, respectively. Using narrow-range pH paper, periodically verify
that sample pH is ~2 for each sample source.

If a sample foams vigorously when added to a VOA vial containing maleic and
ascorbic acids, discard the sample.  Collect another sample for that location, but do
not add the method preservatives. Document these samples as "not acidified."
Unpreserved samples must be analyzed within 24 hours of collection.

If sampling only for the THMs, samples may be preserved with sodium thiosulfate.
Add 3 mg to each 40-mL VOA vial prior to sample collection. Do not add ascorbic
or maleic acid when employing this preservation option.

NOTE: If the residual chlorine is likely to be present at greater than 5 mg/L, a
determination of the chlorine concentration may be necessary. Add an additional 25
mg of ascorbic acid or 3 mg of sodium thiosulfate per each 5 mg/L of residual
chlorine for each 40-mL of sample.

Grab samples must be collected in accordance with standard sampling practices.5
When sampling from a cold water tap, remove the aerator, open the tap  and allow the
system to flush until the water temperature  has stabilized (approximately 3 to 5
minutes). Fill sample bottles to overflowing, but take care not to flush out the rapidly
dissolving solid preservatives.  No air bubbles should pass through the sample as the
bottle is filled or be trapped in the sample when the bottle is sealed.
                                          524.4-14

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         8.1.5   When sampling from an open body of water, fill a beaker with water collected from a
                representative area.  Use this bulk sample to generate individual samples and Field
                replicates as needed.

    8.2  FIELD REAGENT BLANK (FRB)

         8.2.1   A FRB must accompany each sample set unless only THMs are being analyzed. At
                the laboratory, add the sample preservatives to the FRB sample bottle, fill with
                reagent water and ship the FRB with the sampling kits. Do not open the FRB in the
                field; the FRB must remain sealed until analysis. Since total THMs would be
                expected to be present in nearly all disinfected drinking water samples, field blank
                analysis is not required when reporting positive results for total TFDVIs. This
                exception to the analysis of field blanks only applies to the analysis of total TFDVIs as
                disinfection byproducts (DBFs). Positive results for all other chemicals observed
                must be accompanied by the analysis of a field blank to confirm that the positive
                result was not the result of contamination during sample handling or shipment.

         8.2.2   Add the sample preservatives at the laboratory to prepare sample containers for the
                field samples.  The same lots of ascorbic acid and maleic acid must be used for the
                FRB and the field samples.

    8.3  FIELD DUPLICATES - At  a minimum, collect all samples in duplicate. Adequate replicate
         samples in the analytical batch will need to be collected to fulfill QC requirements for LFSMs
         and LFSMDs or FDs.

    8.4  SAMPLE SHIPMENT AND STORAGE - Samples must be chilled during shipment and
         must not exceed 10 C during the first 48 hours after collection.  Samples must be confirmed
         to be at or below 10 C when they are received at the laboratory. In the laboratory, samples
         must be stored at or below 6 C, protected from light and isolated from ambient sources of
         VOCs. When resident in the autosampler, samples must be held at 10  C or lower.  Samples
         must not be frozen.

    8.5  SAMPLE HOLDING TIMES - Analyze samples as soon as possible.  Samples that are
         collected and stored as described in Section 8.1 and 8.4 must be analyzed within 14 days of
         collection.

9.   QUALITY CONTROL

    QC requirements include the Initial Demonstration of Capability and ongoing QC requirements.
    This section describes each QC parameter, its required frequency and the performance criteria that
    must be met in order to satisfy EPA quality objectives.  The QC criteria discussed in the following
    sections are summarized in Section 17, Tables 12 and 13. These QC requirements  are considered
    the minimum acceptable QC criteria. Laboratories are encouraged to institute additional QC
    practices to meet their specific needs. Compliance with the requirements of the IDC must be
    demonstrated for each analyte that the laboratory intends to report using full scan MS and for each
    analyte that the laboratory intends to report in the SIM or SIS detection mode.

    9.1  METHOD MODIFICATIONS - The analyst is permitted to select purge-and-trap and GC
         conditions appropriate for the available instrumentation.  However, five key parameters are
                                           524.4-15

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     restricted to prescribed ranges. These ranges are summarized in the table below. If the
     chosen parameters fall within the "recommended" ranges, the laboratory may proceed with
     the IDC.  If values outside the "recommended" ranges are selected for any one of these five
     parameters, the laboratory must demonstrate equivalent performance in accordance with the
     guidelines provided in Section 9.4 and then the analyst must repeat the procedures of the IDC.
     However, values for the five key parameters must never exceed the "allowable" ranges listed
     in the table below. In addition, sample size cannot be varied from the  5-mL volume
     prescribed in this method. All other parameters including the remaining concentrator
     conditions, GC conditions and MS conditions may be varied without restriction.
Parameter
Sample temperature
Purge flow rate
Purge volume
Desorb time
Purge volume + dry purge volume
Recommended
Minimum
Ambient
40 mL/min
360 mL
1 min
360 mL
Maximum
40 C
55 mL/min
520 mL
1 min
720 mL
Allowable
Minimum
Ambient
20 mL/min
320 mL
0.5 min
320 mL
Maximum
60 C
80 mL/min
520 mL
2 min
720 mL
     NOTE: The "recommended" values provided equivalent response factors and internal
     standard areas compared to helium purge. The "allowable" limits resulted in a wider variation
     in response factors compared to helium purge; however, operation within this range may be
     appropriate for limited analyte lists and other concentrator designs. Sample temperature is
     limited to 60 C to avoid acid-catalyzed decomposition of method analytes.  See Table 2 in
     Section 17 for typical values for purge-and-trap parameters.

9.2  INITIAL DEMONSTRATION  OF CAPABILITY (IDC) - The IDC must be successfully
     performed prior to analyzing any field samples. Prior to conducting the IDC, the analyst must
     meet the calibration requirements outlined in Section 10. The IDC must be completed for
     each concentrator and trap. For example, if dual concentrators are interfaced to a single
     GC/MS, perform the IDC for each system.  If a new trap is installed with sorbent materials
     different from the original trap,  repeat the IDC.  Requirements for the IDC are described in the
     following sections and are summarized in Table 12.

     9.2.1    DEMONSTRATION OF LOW SYSTEM BACKGROUND - Analyze a LRB.
             Confirm that the blank is free of contamination as defined in Section 9.3.1.

             NOTE:  The system must be checked for carryover by analyzing a LRB immediately
             following the highest calibration standard. If this LRB does not meet the criteria
             outlined in Section 9.3.1, then carryover is present and the cause must be identified
             and eliminated.

     9.2.2    DEMONSTRATION OF PRECISION -  Prepare and analyze seven replicate LFBs.
             Fortify these samples near the midrange of the initial calibration curve. The method
             preservation reagents must be added to the LFBs as  described in Section 8.1. The
             percent relative standard deviation (%RSD) of the concentrations of the replicate
             analyses must be <20% for all method analytes.
                                      524.4-16

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                , _. _.^   Standard Deviation of Measured Concentrations  , nn
               %RSD =	xlOO
                                   Average Concentration

9.2.3   DEMONSTRATION OF ACCURACY - Calculate the average percent recovery
       using the same set of replicate data generated for Section 9.2.2.  The average recovery
       of the replicate analyses must be within +20% of the true value.

                  .. _,          Average Measured Concentration  , ^
                  % Recovery =	x 100
                                   Fortified Concentration

9.2.4   MINIMUM REPORTING LEVEL (MRL) CONFIRMATION - Establish a target
       concentration for the MRL based on the intended use of the data. The lowest
       calibration standard used to establish the initial calibration (as well as the low-level
       Continuing Calibration Check) must be at or below the concentration of the MRL.
       Establishing the MRL concentration too low may cause repeated failure of ongoing
       QC requirements. Confirm the MRL following the procedure outlined below.

       NOTE: Method analytes that are consistently present in the background (e.g.,
       methylene chloride, TEA, chloromethane and bromomethane) should be reported as
       detected in field samples only after careful evaluation of the background levels. In
       such cases, an MRL must be  established at a value no less than three times the
       standard deviation of the mean LRB concentration or three times the mean LRB
       concentration, whichever is greater. This guidance is intended to minimize the
       occurrence of reporting false positive results.

       9.2.4.1   Fortify and analyze seven replicate LFBs at or below the proposed MRL
                concentration. The LFBs must contain the method preservatives as
                specified in Section 8.1. Calculate the mean (Mean) and standard deviation
                (S) for these replicates. Determine the Half Range for the Prediction
                Interval of Results (HRpix) using the equation below
                where S is the standard deviation and 3.963 is a constant value for seven
                replicates.1

       9.2.4.2   Confirm that the Upper and Lower limits for the Prediction Interval of
                Results (PIR = Mean +_ HRpip) meet the upper and lower recovery limits as
                shown below.

                The Upper PIR Limit must be <150% recovery.

                               Mean + HRPIK
                           		x 100 < 150%
                            Fortified Concentration

                The Lower PIR Limit must be >50% recovery.


                                 524.4-17

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                                       Mean - HR
                                                  FIR
                                   Fortified Concentration
                                                         x 100> 50%
             9.2.4.3   The MRL is validated if both the Upper and Lower PIR Limits meet the
                      criteria described above. If these criteria are not met, the MRL has been set
                      too low and must be confirmed again at a higher concentration.

             NOTE: These equations are only valid for seven replicate samples.

      9.2.5   QUALITY CONTROL SAMPLE (QCS) - Analyze a mid-level Quality Control
             Sample (Sect. 9.3.10) to confirm the accuracy of the primary calibration standards.

      9.2.6   DETECTION LIMIT DETERMINATION (optional) - While DL determination is
             not a specific requirement of this method, it may be required by various regulatory
             bodies associated with compliance monitoring.  It is the responsibility of the
             laboratory to ascertain whether DL determination is required based upon the
             intended use of the data.

             Analyses for this procedure must be done over at least three days. Prepare at least
             seven replicate LFBs.  Fortify the LFBs at a concentration estimated to be near the
             DL. This fortification level may be estimated by selecting a concentration at two to
             five times the noise level. The method preservatives must be added to the samples as
             described in Section 8.1. Process the seven replicates through all steps of Section 11.

             NOTE:  If a data set used for the MRL confirmation step of the IDC meets these
             requirements, a DL may be calculated from the MRL confirmation data and no
             additional analyses are necessary.

                 Calculate the DL using the following equation:
                where
                t(n-i,i-a = 0.99) = Student's t value for the 99% confidence level with n-1 degrees of
                               freedom (for seven replicate determinations, the Student's t value
                               is 3.143 at a 99% confidence level),
                n = number of replicates and
                S= standard deviation of replicate analyses.

             NOTE: Do not subtract blank values when performing DL calculations.

9.3     ONGOING QC REQUIREMENTS - This section describes the ongoing QC procedures that
       must be followed when processing and analyzing field samples. Table 13 summarizes these
       requirements.

      9.3.1   LABORATORY REAGENT BLANK (LRB) - Analyze a LRB with each Analysis
             Batch.  The LRB must contain the method preservatives, the internal standards and
             surrogate analytes at the same concentration used to fortify all field samples and
                                       524.4-18

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       calibration standards. Background from method analytes or contaminants that inter-
       fere with the measurement of method analytes must be less than 1A the MRL.  If the
       method analytes are detected in the LRB at concentrations equal to or greater than
       this level, then all data for the problem analyte(s) must be considered invalid for all
       samples that yielded a positive result. Subtracting LRB values from sample results
       is not permitted.

       NOTE:  Although quantitative data below the MRL may not be accurate enough for
       data reporting, such data are useful in determining the magnitude of background
       interference.  Therefore, blank contamination levels may be estimated by
       extrapolation when the concentration is below the MRL.

       NOTE:  After analysis of a sample in which method analytes exceed the calibration
       range, one or more LRBs must be analyzed (to detect potential  carryover) until the
       system meets the LRB acceptance criteria. If this occurs during an automated
       sequence, examine the results of samples analyzed following the sample that
       exceeded the calibration range. If the analytes that exceeded the calibration range in
       the previous sample are detected at or above the MRL, these samples are invalid. If
       the affected analytes do not exceed the MRL, these subsequent samples are valid.
       THMs are excluded from this requirement.

       NOTE:  The LRB test in the IDC may be particularly difficult to pass for compounds
       analyzed using the SIM detection mode. For analytes monitored in SIM mode, the
       laboratory should restrict the high calibration point to 1.0 or 2.0 |ig/L and consider
       other techniques such as using a dedicated sparge vessel and more aggressive recycle
       parameters.  If possible, select MRLs that allow monitoring goals to be achieved, but
       that are well above typical blank values.

9.3.2   CONTINUING CALIBRATION CHECK (CCC) - Analyze CCC standards at the
       beginning of each Analysis Batch, after every ten field samples and at the end of the
       Analysis Batch. See Section 10.2 for concentration requirements and acceptance
       criteria.

9.3.3   LABORATORY FORTIFIED BLANK (LFB) - Because this method utilizes
       procedural calibration standards, which are fortified reagent waters, there is no
       difference between the LFB and the CCC standards.  Consequently, the analysis of a
       separate LFB is not  required as part of the ongoing QC; however, the term "LFB" is
       used for clarity in the IDC.

9.3.4   MS TUNE CHECK - The procedure for conducting the MS Tune Check for BFB is
       found in Section 10.1.1.  Acceptance criteria for the MS Tune Check are summarized
       in Section 17, Table 1.  The MS Tune Check must be performed prior to establishing
       and/or re-establishing an initial calibration (Sect. 10.1) and each time a major change
       is made to the mass  spectrometer. Daily BFB  analysis is not required.

9.3.5   INTERNAL STANDARDS (IS) - The analyst must monitor the peak areas of the
       internal standards in all injections of the Analysis Batch.  The IS responses (peak
       area) in any chromatographic run must not deviate from the response in the most
       recent CCC by more than +30% and must not deviate by more than +50% from the
                                 524.4-19

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        average area measured during initial analyte calibration. If an IS area for a sample
        does not meet these criteria, check the corresponding IS area of the most recent CCC
        and proceed as follows.

        9.3.5. 1   If the IS criteria are met in the CCC but not the sample, reanalyze the
                sample (FD) in a subsequent Analysis Batch.  If the IS area fails to meet the
                acceptance criteria in the FD, but passes in the most recent CCC, report the
                sample results as "suspect/matrix."

        9.3.5.2   If both the original sample and the CCC fail the IS criteria, take corrective
                action beginning with an extended bake cycle for the GC column and the
                concentrator trap. Area counts may decrease as the rate of water entering
                the mass spectrometer exceeds the capacity of the pumping system to
                remove it. Additional measures  such as clipping the inlet side of the GC
                column and cleaning the MS source may be indicated. Verify the integrity
                of the IS solution and the fortification technique.  Perform the appropriate
                instrument maintenance and then reanalyze the sample (FD) in a subsequent
                Analysis Batch.  If the IS area fails to meet the acceptance criteria in the FD,
                but passes in the most recent CCC, report the sample results as
                "suspect/matrix."

9.3.6    SURROGATE RECOVERY - The surrogate analytes are fortified into all calibration
        standards, field samples and QC samples prior to purge-and-trap analysis.  Calculate
        the percent recovery (%R) for each surrogate using the following equation:

                                         ( /c\
                                   %R=    xlOO
           where
           A = calculated surrogate concentration for the QC or field sample and
           B = fortified concentration of the surrogate.

        9.3.6.1   Surrogate recovery must be in the range of 70% to 130%. When surrogate
                recovery from a field sample, blank or QC sample is less than 70% or
                greater than 130% check: 1) calculations to locate possible errors, 2) the
                integrity of the surrogate analyte solution and the fortification technique,
                3) contamination and 4) instrument calibration.  Also, see corrective action
                options in Section 9.3.5.2.  Correct the problem  and reanalyze the sample in
                a subsequent Analysis Batch using the appropriate FD.

        9.3.6.2   If the repeat analysis meets the surrogate recovery criterion, only report data
                for the FD.

        9.3.6.3   If the FD fails the surrogate recovery criterion after corrective action has
                been taken, report all data for that sample as "suspect/surrogate recovery."

9.3.7    LABORATORY FORTIFIED SAMPLE MATRIX (LFSM) - Within each Analysis
        Batch, analyze a minimum of one LFSM.  The native concentrations of the analytes

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in the sample matrix must be determined in a separate aliquot and subtracted from the
measured values in the LFSM. If a variety of different sample matrices are analyzed
regularly, for example, drinking water from ground water and surface water sources,
performance data must be collected for each source.

9.3.7. 1   Prepare the LFSM by fortifying a FD with an appropriate amount of an
         analyte PDS  (Sect. 7.3.2). Select a spiking concentration that is greater than
         or equal to the native background concentration, if known.  Selecting a
         duplicate aliquot of a sample that has already been analyzed aids in the
         selection of an appropriate spiking level.  If this is not possible, use
         historical data and rotate through low, medium and high calibration
         concentrations when selecting a fortifying concentration.

         NOTE: If the presence of DBFs (e.g., THMs) precludes selection of an
         appropriate fortification level for the majority of the method analytes, the
         DBFs may be ignored. For example, if the analyst wishes to estimate
         accuracy and precision at 1.0 |ig/L and chloroform is present in the native
         matrix at 10  |ig/L, chloroform is fortified at only  10% of its native
         concentration. In such cases, recovery results for the DBFs may fail the
         acceptance criteria for LFSM.  Appropriately qualify the QC result when
         this occurs.  If the laboratory is analyzing specifically for DBFs or does not
         wish to exclude  them, select a fortification level based on the DPB
         concentrations in the native sample such that the final DBF results fall
         within the calibration range.

9.3.7.2   Calculate the percent recovery (%R) using the equation:
                              C

        where
        A = measured concentration in the fortified sample
        B = measured concentration in the unfortified sample and
        C = fortification concentration.

9.3.7.3  Recoveries for samples fortified at concentrations near or at the MRL
        (within a factor of two times the MRL concentration) must be within +50%
        of the true value. Recoveries for samples fortified at all other concentrations
        must be within +30% of the true value. If the accuracy for any analyte falls
        outside the designated range and the laboratory performance for that analyte
        is shown to be in control  in the CCCs, the recovery is judged matrix biased.
        The result for that analyte in the unfortified sample is labeled
        "suspect/matrix."

        NOTE: In order to obtain meaningful percent recovery results,  correct the
        measured values in the LFSM and LFSMD for the native levels in the
        unfortified samples, even if the  native values are less than the MRL.  This
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               situation and the LRB are the only permitted uses of analyte results below
               the MRL.

9.3.8   FIELD DUPLICATE OR LABORATORY FORTIFIED SAMPLE MATRIX
       DUPLICATE (FD or LFSMD) - Within each Analysis Batch, analyze a minimum of
       one FD or one LFSM Duplicate. If method analytes are not routinely observed in
       field samples, analyze an LFSMD rather than an FD.

       9.3.8. 1  Calculate the relative percent difference (RPD) for duplicate measurements
               (FDi and FD2) using the equation:
                                        FD, -FD7
                                             FD2)/2
                                                     lOO
       9.3.8.2  RPDs for FDs must be <30%. Greater variability may be observed when
               FDs have analyte concentrations that are near or at the MRL (within a factor
               of two times the MRL concentration). At these concentrations, FDs must
               have RPDs that are <50%. If the RPD of an analyte falls outside the
               designated range and the laboratory performance for the analyte is in control
               in the CCC, the precision is judged matrix influenced. The result from the
               unfortified sample is labeled "suspect/matrix."

       9.3.8.3  If an LFSMD is analyzed instead of a FD, calculate the RPD for the LFSM
               and LFSMD using the equation:

                                 LFSM -LFSMD
                                (LFSM + LFSMD)/2


       9.3.8.4  RPDs for duplicate LFSMs must be <30%. Greater variability may be
               observed when fortified LFSMs have analyte concentrations that are near or
               at the MRL (within a factor of two times the MRL concentration). LFSMs
               at these concentrations must have RPDs that are <50%. If the RPD of an
               analyte falls outside the designated range and the laboratory performance for
               that analyte is in control in the CCC, the precision is judged matrix
               influenced. The result from the unfortified sample is labeled
               "suspect/matrix."

9.3.9   FIELD REAGENT BLANK (FRB) - FRBs must be analyzed if compounds other
       than commonly  occurring DBFs, such as THMs, are detected in field samples.
       Qualify the result for any analyte that is detected in both a field  sample and in the
       associated FRB  as "probable contribution from shipping and storage."  Subtracting
       FRB values from sample results is not permitted.

9.3.10  QUALITY CONTROL SAMPLE (QCS) - A QCS must be evaluated as part of the
       IDC and repeated at least quarterly. Fortify the QCS near the midpoint of the
       calibration range. The acceptance criteria for the QCS are the same as the mid-level
       and high-level CCCs (Sect.  10.2.1). If the accuracy for any analyte fails the recovery
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             criterion, check the standard preparation process, stock standard sources and the
             purity of neat materials used to prepare the stock standards to locate and correct the
             problem.

9.4  METHOD MODIFICATION QC REQUIREMENTS - The analyst is permitted to modify the
     five key purge-and-trap parameters (sample temperature, purge flow rate, purge volume,
     desorb time and dry purge volume). The analyst is not permitted to modify sample collection
     or preservation, change the QC requirements of the method or increase the sample volume
     above 5 mL. Do not add or delete QC compounds from the list prescribed in the method: ISs
     (Sect. 7.2.1) and surrogates (Sect. 7.2.2).  If modified parameters fall outside of the
     "recommended" minimum and maximum for one of the five key parameters the laboratory
     must confirm that the new parameters provide acceptable method performance as defined in
     the following subsections.

     9.4.1    The new parameters must fall within the "allowable" minimum and maximum limits
             specified in Section 9.1. Values outside these limits are not permitted.

     9.4.2    Perform an initial calibration procedure  (Sect. 10.1) for the method analytes that the
             laboratory  intends to report using conditions that fall within the "recommended"
             ranges as presented in Section 9.1.  Determine relative response factors (RRF) for
             each analyte averaged over the entire calibration range.

                                       Analyte (area) x IS (|ig/L)
                                 KKr  = -.	r	
                                       IS (area) x Analyte (ng/L)

     9.4.3    Optimize the purge-and-trap system using the proposed method modifications.
             Analyze three mid-level calibration standards and calculate mean RRFs for each
             method analyte.  If all of the response factors observed using the modified conditions
             are >70% of the initial calibration response factors obtained using the
             "recommended" method conditions (Sect. 9.4.2), then the modified method
             parameters are permitted. Repeat the procedures of the IDC (Sect. 9.2) employing the
             modified parameters.

     9.4.4    The analyst is also required to evaluate and document method performance for the
             proposed method modifications in real matrices that span the range of waters that the
             laboratory  analyzes. This additional step is required because modifications that
             perform acceptably in the IDC, which is conducted in reagent water, could fail
             ongoing method QC requirements in real matrices. If, for example,  the laboratory
             analyzes drinking water from both surface and ground water municipalities, this
             requirement can be accomplished by assessing precision and accuracy (Sects.  9.2.2
             and 9.2.3) in  a surface water with moderate to high total organic carbon (e.g.,  2 mg/L
             or greater)  and a hard ground water [e.g., 250 mg/L as calcium carbonate (CaCOs)
             equivalent  or greater].

     9.4.5    The results of Sections 9.4.3 and 9.4.4 must be appropriately documented by the
             analyst and should be independently assessed by the laboratory's QA officer prior to
             analyzing field samples.


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         9.4.6   When implementing method modifications, it is the responsibility of the laboratory to
                closely review the results of ongoing QC and in particular, the results associated with
                the LFSM (Sect. 9.3.7), LFSMD (Sect. 9.3.8), CCCs (Sect. 9.3.2) and the IS area
                counts (Sect. 9.3.5). If repeated failures are noted, the modification must be
                abandoned.

10.  CALIBRATION AND STANDARDIZATION

    Demonstration and documentation of acceptable analyte calibration is required before performing
    the IDC (Sect. 9.2) and prior to analyzing field samples.  Verification of the MS calibration and the
    initial calibration must be repeated each time a major instrument modification or maintenance is
    performed.

    NOTE: For tandem concentrators or older systems that utilize multiple sparging vessels and/or
    traps, a separate calibration and all required QC samples must be analyzed on each sample path. In
    addition, a qualitative marker compound must be added to all samples to uniquely identify the
    sample path and ensure that samples are matched to the proper calibration and QC results.  For
    example, fluorobenzene could be added to all samples analyzed on the second sample path of a
    tandem concentrator system.

    10.1  PURGE-AND-TRAP GC/MS OPTIMIZATION AND INITIAL CALIBRATION - An initial
         calibration requires optimizing purge-and-trap and GC/MS conditions, confirming that the
         instrument meets the BFB tune check criteria and the preparation and analysis of at least
         seven calibration standards to determine the calibration curve. Calibration must be performed
         using  peak areas and the internal  standard technique. Calibration using peak heights and
         external standard calibration are not permitted.

         10.1.1 MS TUNE/MS TUNE CHECK- Calibrate the mass and abundance scales of the MS
                utilizing calibration compounds and procedures recommended by the manufacturer
                with any modifications necessary to meet tuning requirements.  Introduce BFB (Sect.
                7.5) into the GC/MS system. Acquire a mass spectrum using the same scan range
                employed for full scan sample analyses. Use a single spectrum at the apex of the
                BFB peak, an average spectrum of the three highest points of the peak or an average
                spectrum across the entire peak to evaluate the performance of the system.
                Appropriate background subtraction is allowed; however, the background scan(s)
                must be chosen from the baseline prior to or after elution of the BFB peak. If the
                BFB mass spectrum does not meet all criteria in Table 1, the MS must be retuned to
                meet all criteria before proceeding with the initial calibration.

         10.1.2 PURGE-AND-TRAP CONDITIONS - Establish purge-and-trap parameters
                following the manufacturer's recommendations. Make sure that the sample
                temperature, purge flow rate, purge volume,  desorb time and dry purge volume are
                within the "allowable" ranges specified in  section 9.1. Optimize purge-and-trap
                parameters to maximize purging efficiency and minimize the transmission of water to
                the GC/MS system.

         10.1.3 GC CONDITIONS - Establish GC operating conditions appropriate for the GC
                column dimensions by optimizing  the split ratio and temperature program. Generally,
                the required split ratio is inversely  proportional to column diameter.  The user must
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       balance the need to transfer enough of the method analytes to achieve the desired
       MRLs and the need to reduce water transmission from the purge-and-trap
       concentrator. The split ratio will also affect the chromatographic peak profile of the
       most volatile method analytes, commonly referred to as "gases." Sufficient
       resolution and symmetrical peak profiles with minimal tailing for these analytes must
       be achieved to enable accurate and precise integration. A mass chromatogram of the
       gases obtained during method development is provided in Figure 1.  The GC program
       must be optimized to provide adequate resolution of the method analytes as defined in
       the following subsections.

       10.1.3.1 If possible, optimize chromatographic conditions such that a unique
               quantitation ion is available for each analyte that is free from interference
               due to an identical fragment ion in any co-eluting (or overlapping) peak(s).

       10.1.3.2 If a unique quantitation ion of sufficient intensity to set the desired MRL is
               not available, overlap with an identical ion from an overlapping analyte is
               permitted, providing that at least a 50% valley between the mass peaks is
               achieved.

10.1.4  FULL SCAN MS CONDITIONS - Select a scan range that  allows the acquisition of
       a mass spectrum for each of the method analytes, which includes all of the  major
       fragments mass-to-charge ratio (m/z) 35 and above.  However, during elution of the
       water/carbon dioxide peak, the analyst is permitted to begin  the scan at m/z 45 to
       eliminate the appearance of these matrix components in the baseline.

10.1.5  SIM MS CONDITIONS - In SIM mode, choose  one primary quantitation ion and at
       least one secondary ion. If possible, select a second  confirmation ion. Additional
       ions may be monitored that demonstrate a unique characteristic in the mass spectrum
       such as a halogen cluster.  Verify that the primary ion is free from interference (Sect.
       10.1.3.1 and Sect. 10.1.3.2) due to an identical fragment ion in any overlapping
       peak(s). If the chromatogram is divided into SIM windows (also termed segments or
       periods), the laboratory must ensure that each method analyte elutes entirely within
       the proper window during  each Analysis Batch. Make this observation by  viewing
       the mass chromatogram of the quantitation ion for each SIM analyte in the CCC
       analyzed at the beginning and end of each Analysis Batch. This requirement does not
       preclude continuous operation by sequencing multiple Analysis Batches; however,
       the entire Analysis Batch is invalid if one or more analyte peaks drift outside of
       designated SIM windows in either of these CCCs. For large analyte lists, minimize
       the number of ions monitored in each chromatographic window to ensure adequate
       sensitivity to meet the desired MRL. During method development, five SIM
       windows were used as indicated in Section 17, Table 5.

10.1.6  ALTERNATING FULL AND SIM SCAN MODES  - Alternating full and  SIM scan
       functions during a single sample acquisition is permitted if the minimum number of
       scans across each GC peak acquired in this mode is maintained, i.e., six scans as
       specified in  Section 6.9.4 in each full and SIM scan modes.

10.1.7  CALIBRATION STANDARDS - Prepare a set of at least seven calibration standards
       as described in Section 7.4. The lowest concentration of the calibration standards
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            must be at or below the MRL.  The MRL must be confirmed using the procedure
            outlined in Section 9.2.4 after establishing the initial calibration.  Additionally, field
            samples must be quantified using a calibration curve that spans the same
            concentration range used to collect the IDC data (Sect. 9.2), i.e., analysts are not
            permitted to use a restricted calibration range to meet the IDC criteria and then use a
            larger dynamic range during analysis of field samples.

     10.1.8  CALIBRATION - Calibrate the GC/MS system using peak areas and the internal
            standard technique. Fit the calibration points with either a linear or a quadratic
            regression (response vs. concentration). Weighting may be used. The GC/MS
            instrument used during method development was calibrated using inverse
            concentration-weighted quadratic curves.  Suggested internal standard assignments
            and quantitation ions for each method analyte evaluated in full scan mode are
            presented in Table 4. Suggested internal standard assignments and quantitation ions
            for each method analyte evaluated in SIM mode are presented in Table 5.

            NOTE: Because the surrogate analytes are added at a single concentration level to the
            calibration standards, calibrate for each surrogate using an average response factor.

     10.1.9  FORCING ZERO - Forcing the calibration curve through the origin is not
            recommended.  However, zero must be forced for method analytes (e.g., common
            laboratory contaminants and for carbon-based traps, potentially chloromethane and
            bromomethane) if they are consistently detected in the Laboratory Reagent Blanks.
            Forcing zero allows for a better estimate of the background level of blank
            contaminants. An accurate estimate of background contamination is necessary to set
            MRLs for method analytes when blank levels are problematic (Sect. 9.2.4).

     10.1.10 CALIBRATION ACCEPTANCE CRITERIA - The initial calibration is validated by
            calculating the concentration of the analytes for each of the analyses used to generate
            the calibration curve by use of the regression equations.  Calibration points that are
            
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                are still within holding time must be reanalyzed after an acceptable calibration has
                been restored.

         10.2.2  REMEDIAL ACTION - Failure to meet QC performance criteria for CCCs requires
                remedial action.  Acceptable method performance may be restored simply by
                recalibrating in accordance with the guidelines in Section 10.1 and verifying
                sensitivity by analyzing a CCC at or below the MRL.  Because of the volatile nature
                of the method analytes, PDS have limited shelf life. Prepare a fresh PDS and repeat
                the CCC before contemplating instrument maintenance. If internal standard  and
                calibration failures persist, maintenance such as extended bake cycles for both the
                purge-and-trap concentrator and the GC/MS, clipping the GC column, replacing the
                concentrator trap and cleaning the MS source may be required. Following major
                maintenance, the analyst must return to the initial calibration step (Sect. 10.1).

11.   PROCEDURE

     Important aspects of this  analytical procedure include proper sample collection and storage
     (Section 8), ensuring that the instrument is properly calibrated (Section 10) and that all required
     QC elements are included (Section 9).  This method is designed for a 5-mL sample volume. The
     concentration of the internal standards  and surrogate analytes must be the same in the samples as
     in the calibration standards. In the laboratory, maintain field samples,  QC samples and calibration
     standards at or below 6 C at all times while in storage.  While resident in the autosampler
     awaiting analysis, samples must be maintained at less than or equal to  10 C. Do not store samples
     in the autosampler longer than the time required to complete the Analysis Batch.

     11.1  SAMPLE PREPARATION: SYRINGE METHOD - For concentrators with a single
           sparging vessel and autosamplers with multiple sparging vessels, load the sample (or
           previously prepared calibration standard) by use of a 5-mL syringe. If the purge cycle will
           be initiated immediately after this step, warm the sample to room temperature. Remove the
           plunger from two syringes and attach a closed syringe valve.  Open the VOA vial and
           carefully pour the sample into the syringe barrel 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 5  mL. Add the internal
           standard/surrogate analyte PDS to the sample through the syringe valve.  Immediately load
           the sample into the sparging vessel.

           NOTE: Do not store samples in syringes or prepare QC samples by filling two syringes. A
           second VOA vial (i.e., a FD) is required as a means of ensuring  that a back up sample is
           available  and for preparing FD, LFSM and LFSMD QC samples.

           11.1.1 PREPARATION OF LFSM and LFSMD: SYRINGE METHOD - Three 40-mL
                 vials (FDs) are required for a sample and its associated LFSM and LFSMD.  Fortify
                 two of the samples using an analyte PDS of appropriate concentration by injecting
                 through the syringe valve. Add the internal standards and surrogates as directed in
                 Section 11.1.

           11.1.2 FIELD DUPLICATE: SYRINGE METHOD - Fill a 5-mL syringe with the selected
                 FD and fortify with internal standards and surrogates. Analyze FDs at the frequency
                 specified in Section 9.3.8.
                                          524.4-27

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11.2   SAMPLE PREPARATION: VIAL AUTOSAMPLER METHOD - Activate the cooling
      mechanism of the refrigerated autosampler and allow it to reach the temperature set point.
      Remove samples from cold storage and immediately load them into the vial autosampler.
      Prepare the IS/surrogate fortification solution at a concentration appropriate for the
      automated standard addition device.

      11.2.1 PREPARATION OF LFSM and LFSMD FOR VIAL AUTOSAMPLERS - Three
            40-mL vials (FDs) are required for a sample and its associated LFSM and LFSMD.
            Fortify two of the samples using an analyte PDS of appropriate concentration by
            puncturing the septa of each vial with a syringe. Allow time for the compounds to
            disperse homogeneously within the sample.  Assume that the sample volume is 40
            mL or estimate the typical volume of a 40-mL vial in use at your laboratory.
            Fortification may be accomplished by use of a standard addition module if the
            autosampler is so equipped.

      11.2.2 FDs FOR VIAL AUTOSAMPLERS - Load the appropriate FD vial into the
            autosampler.  Analyze FDs at the frequency specified in Section 9.3.8.

11.3   PURGE-AND-TRAP ANALYSIS

      11.3.1 Establish purge-and-trap and GC/MS operating conditions per the guidance in
            Section 10.1.

      11.3.2 Bake the concentrator trap and GC column to remove contaminants that may have
            collected in the system.  This step is especially important if the analytical system has
            been idle for more than a few hours.

      11.3.3 Initiate the purge cycle and autosampler sequence.  After the purge  cycle, preheat the
            trap as recommended by the manufacturer. Start the data acquisition at the
            beginning  of the desorb cycle. Bake the trap and rinse the sparging vessel and
            autosampler delivery lines using settings optimized to minimize sample carryover.

            NOTE:  The method preservatives cause the water column in the sparging vessel to
            appear effervescent during the purge cycle. This is normal and no adverse effects
            occur as a  result of the effervescence.

11.4   THE ANALYSIS BATCH - Establish a valid initial calibration following the procedures
      outlined in Section 10.1 and confirm that the calibration is  still valid by analyzing a CCC at
      or below the MRL as described in Section 10.2. Alternately, verify that an existing
      calibration, established for a previous Analysis Batch, is valid by analyzing a CCC at or
      below the MRL. Next, analyze a LRB.  Continue the Analysis Batch by analyzing aliquots
      of field and QC samples at appropriate frequencies (Section 9.3), employing the optimized
      conditions used to acquire the initial calibration. Analyze a mid- or high-level CCC after
      every ten field samples and at the end each Analysis Batch.

      NOTE: Each Analysis Batch must begin with the analysis  of a CCC at or below the MRL
      for each analyte that the laboratory intends to report, followed by the analysis of a LRB.
      This is true whether or not an initial calibration is analyzed. After 20 field  samples, the low-
                                     524.4-28

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           level CCC and the LRB must be repeated to begin a new Analysis Batch. The acquisition
           start time of the mid-level CCC at the end of the Analysis Batch must be within 24 hours of
           the acquisition start time of the low-level CCC at the beginning of the Analysis Batch.
           Multiple Analysis Batches within a 24-hour period are permitted.  Do not count QC samples
           (LRBs, FRBs, FDs, LFSMs,  LFSMDs) when calculating the frequency of CCCs that are
           required during an Analysis Batch.

12.  DATA ANALYSIS AND CALCULATIONS

    12.1  COMPOUND IDENTIFICATION - Establish an appropriate retention time window for each
          analyte to identify them in QC and field sample chromatograms. Base this assignment on
          measurements of actual retention time variation for each compound in standard solutions
          analyzed on the GC/MS over  the course of time. The suggested variation is plus or minus
          three times the standard deviation of the retention time for each compound for a series of
          injections. The injections from the initial calibration and from the IDC (Sect. 9.2) may be
          used to calculate the retention time window. However, the experience of the analyst should
          weigh heavily on the determination of an appropriate range.

          12.1.1  At the conclusion of data acquisition, use the same software  settings established
                 during the calibration  procedure to identify peaks of interest in the predetermined
                 retention time windows. Initially, identify an analyte by comparison of its retention
                 time with that of the corresponding analyte peak in a recent initial calibration
                 standard or CCC.

          12.1.2  Some GC/MS programs use spectra matching criteria when collecting data in full
                 scan mode based on the comparison of field sample spectra (after background
                 subtraction if necessary) to a reference spectrum in the user-created database. This
                 database should be created prior to conducting the IDC from spectra obtained for a
                 mid-level to high-level calibration standard and updated as necessary.  If available,
                 this feature may be utilized as a secondary identification routine; however, the
                 primary criterion must be based on the analyte retention time.

    12.2  COMPOUND CONFIRMATION FULL SCAN MODE - In general, all ions that are present
          above 30 percent relative abundance in the mass spectrum of the user-generated database
          must be present in the mass spectrum of the sample component and must agree within an
          absolute 20 percent of the relative abundance in the reference spectrum.  For example, if an
          ion has a relative abundance of 30 percent in the standard spectrum, its abundance in the
          sample spectrum must be in the range of 10 to 50 percent.  Some ions, particularly the
          molecular ion, are of special importance and should be evaluated even if they are  below 30
          percent relative abundance.

          NOTE: Compound identification is more challenging 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), characteristic
          analyte spectra may be obtained by examining the spectra of individual scans across the peak
          and then applying appropriate background subtraction.  When analytes co-elute (i.e., only
          one GC peak is apparent), the identification criteria may be met but  each analyte spectrum
          will contain extraneous ions contributed by the co-eluting compound.
                                           524.4-29

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    12.3  COMPOUND CONFIRMATION SIM MODE - In SIM mode, each confirmation ion should
          be present. For each analyte identified by retention time, the abundance of the confirmation
          ions relative to the quantitation ion should agree within an absolute 20 percent of the relative
          abundance in the spectrum taken from a recent calibration standard analyzed in SIM mode.
          For example, if an ion has a relative abundance of 30 percent in the calibration standard, its
          abundance in the sample spectrum should be in the range of 10 to 50 percent.

    12.4  COMPOUND QUANTITATION - Calculate analyte concentrations using the multipoint
          calibration established in Section 10.1. Report only those values that fall between the MRL
          and the highest calibration standard.

          12.4.1  Calculations must use all available digits of precision, but final reported
                 concentrations should be rounded to an appropriate number of significant figures (one
                 digit of uncertainty); this is typically two and not more than three, significant figures.

          12.4.2  Prior to reporting data, the chromatograms must be reviewed for incorrect peak
                 identification or improper integration.

          12.4.3  Prior to reporting data, the laboratory is responsible for assuring that QC
                 requirements have been met and that any appropriate qualifier is assigned.

    12.5  EXCEEDING THE CALIBRATION RANGE - The analyst must not extrapolate beyond the
          established calibration range.  If an analyte result exceeds the range of the initial calibration
          curve, dilute the FD using reagent water containing the method preservatives. Re-inject the
          diluted sample. Incorporate the dilution factor into final concentration calculations. The
          resulting data must be annotated as a dilution and the reported MRLs must reflect the dilution
          factor.

13. METHOD PERFORMANCE

References to specific brands or catalog numbers are included as examples only and do not imply
endorsement of the product.  These references do not preclude the use of other vendors or supplies.

    13.1 PRECISION, ACCURACY AND DETECTION LIMITS - The method performance data
         presented in Section  17 were collected using a Tekmar Stratum Purge-and-trap Concentrator
         with a Tekmar AQUATek 70 Vial Autosampler interfaced to an Agilent 6890 Plus  GC and an
         Agilent 5973 MS.  Table 2 lists the purge-and-trap conditions used to gather the method
         performance  data presented in Section 17. GC/MS conditions for the Agilent system are
         presented in Table 3. Table 4 presents the quantitation ions employed in full scan mode
         appropriate for the Restek Rtx-VMS column (no interference from overlapping peaks) for
         each analyte, internal standard and surrogate analyte,  suggested internal standard assignments
         and observed retention times associated with the method performance results. Table 5 lists
         the method analytes for which method performance data were collected in the SEVI  mode;
         primary quantitation ions, confirmation ions and internal standard references are provided.
         Single laboratory LCMRLs and DLs determined in full scan mode are listed in Table 6.
         Single laboratory precision and accuracy data obtained in full scan mode are presented for
         three water matrices: reagent water (Table 7), chlorinated (finished) ground water (Table 8)
         and chlorinated (finished) surface water (Table 9).  LCMRLs and DLs obtained in SEVI mode
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         for selected method analytes are presented in Table 10.  Figure 1 depicts an extracted ion
         chromatogram of the method analytes that are gases at room temperature acquired in full scan
         mode.  Figures 2 and 3 are total ion chromatograms of the method analytes in reagent water
         and drinking water obtained under the conditions employed during method development in
         full scan mode. Figure 4 depicts an extracted ion chromatogram of the method analytes that
         are gases at room temperature acquired in SIM mode. Figure 5 is a total ion chromatogram of
         the method analytes in reagent water obtained under the conditions employed during method
         development in SIM mode.

    13.2 SAMPLE STORAGE STABILITY STUDIES - An analyte storage stability study was
         conducted during the development of EPA Method 524.3 by fortifying the analytes (20 ug/L
         of each analyte) into a chlorinated surface water that was collected, preserved and stored as
         described in Section 8. The average recovery of triplicate analyses, conducted on Days 0, 7
         and 14 are presented in Table 11.  These results are reproduced in Method 524.4 to document
         that storage stability for the method analytes has been demonstrated.

14.  POLLUTION PREVENTION

    For information about pollution prevention applicable to laboratory operations described in this method,
    consult: Less is Better, Guide to Minimizing  Waste in Laboratories, a web-based resource available
    from the American Chemical Society website.

15.  WASTE MANAGEMENT

    The analytical procedures described in this method generate relatively small amounts of waste since
    only small amounts of reagents and solvents are used. The matrix of concern is finished drinking
    water.  However, the Agency requires that laboratory waste management practices be conducted
    consistent with all applicable rules  and  regulations and that laboratories protect the air, water and
    land by minimizing and controlling all releases from fume hoods and bench operations. In addition,
    compliance is required with any sewage discharge permits and regulations, particularly the
    hazardous waste identification rules and land disposal restrictions.

16.  REFERENCES

    1.    Winslow,  S. D.; Pepich, B. V.; Martin, J. I; Hallberg, G. R.; Munch D. I; Frebis, C. P.;
         Hedrick, E. J.;  Krop, R. A. Statistical Procedures for Determination  and Verification of
         Minimum Reporting Levels for Drinking Water Methods. Environ. Sci. Technol.  2006; 40,
         281-288.

    2.    Glaser, J.A.; Foerst, D.L.; McKee, G.D.; Quave, S.A.; Budde, W.L.  Trace Analyses for
         Wastewaters.  Environ. Sci. Technol.  1981;  15, 1426-1435.

    3.    Occupational Exposures to Hazardous Chemicals in Laboratories, 29 CFR 1910.1450,
         Occupational Safety and Health Administration.

    4.    Safety in Academic Chemistry Laboratories; American Chemical Society Publication;
         Committee on  Chemical Safety: 7th Edition, 2003.
                                           524.4-31

-------
5.    Standard Practice for Sampling Water from Closed Conduits; ASTM Annual Book of
     Standards, Section  11, Volume 11.01, D3370-07; American Society for Testing and Materials:
     Philadelphia, PA, 2007.
                                      524.4-32

-------
17.  TABLES, DIAGRAMS, FLOWCHARTS and VALIDATION DATA
The conditions listed in the tables of this section were used to collect method performance data at EPA.
They do not represent any form of guidance for acceptable parameter settings.  Refer to the relevant
sections of the method for guidance on optimizing and selecting purge-and-trap and GC/MS conditions.

TABLE 1. 4-BROMOFLUOROBENZENE (BFB) MASS INTENSITY CRITERIA
m/z
95
96
173
174
175
176
177
Required Intensity (relative abundance)
Base peak, 100% relative abundance
5to9%ofw/z95
Less than 2% of m/z 174
Greater than 50% of m/z 95
5 to 9% of m/z 174
Greater than 95% but less than 105% of m/z 174
5 to 10% of m/z 176
TABLE 2. PURGE-AND-TRAP CONDITIONS USED FOR METHOD PERFORMANCE
RESULTS
Parameter
Sample volume
Sample purge temperature
Trap
Purge cycle
Condenser purge temperature
Dry purge
Desorb preheat temperature
Desorb cycle
Bake rinse cycles
Bake cycle
Conditions"
5mL
40 C
Supelco K-Trap (Vocarb 3000)
40 mL/min for 1 1 min
20 C
100 mL/min for 3 min
250 C
260 C for 1.0 min
Sparging vessel and autosampler sample path rinsed twice
260 C for 6 min @ 200 mL/min
   The chromatograms presented in Figures 2 and 3 were obtained under these conditions.
                                        524.4-33

-------
TABLE 3. GAS CHROMATOGRAPHY/MASS SPECTROMETRY (GC/MS) CONDITIONS
FOR METHOD PERFORMANCE RESULTS
Parameter
Column
Inlet liner
Inlet conditions
GC temperature program
Solvent delay
MS source temperature
MS quadrupole temperature
GC/MS interface
Full scan window 1
Full scan window 2
SEVI parameters
Conditions11
Restek Rtx-VMS 30 meter, 0.25 mm i.d., 1.4 |im df
1-mm i.d., deactivated glass
30:1 split ratio, 200 C, helium carrier gas, column flow rate: 0.9
mL/min
45 C for 4.5 min, 12 C/min to 100 C, hold 0 min, 25 C to 240 C,
hold 3. 32 min
1.5 min before activating filaments in the electron impact source
230 C
150 C
Direct, 240 C
m/z 47 to 150 (1.7 to 2.9 min)
m/z 35 to 260 (2.9 min to 18 min)
multiple retention time windows; dwell times set to allow seven to 10
scans across chromatographic peaks
TABLE 4. RETENTION TIMES, RECOMMENDED QUANTITATION IONS and
SUGGESTED INTERNAL STANDARD REFERENCES FOR FULL SCAN MODE"
Analyte
dichlorodifluoromethane
chlorodifluoro methane
chloro methane
vinyl chloride
1,3 -butadiene
bromo methane
trichlorofluoromethane
diethyl ether
1,1-dichloroethene
carbon disulfide
methyl iodide
allyl chloride
methylene chloride
trans-l,2-dichloroethene
methyl acetate
methyl-t-butyl ether- d3 (surrogate #1)
methyl-t-butyl ether (MtBE)
t-butyl alcohol (TEA)
diisopropyl ether (DIPE)
1,1-dichloroethane
t-butyl ethyl ether (ETBE)
cis-l,2-dichloroethene
bromochloromethane
Peak no. Fig.'s 2a, 2b, 2c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
RT
1.84
1.90
2.05
2.10
2.11
2.40
2.66
2.98
3.18
3.23
3.36
3.74
3.87
4.08
4.10
4.21
4.23
4.38
4.77
4.94
5.29
5.68
5.95
Q-Ion
85
51
50
62
54
94
101
59
96
76
142
76
84
96
43
76
73
59
45
63
59
96
128
ISb Reference
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
                                524.4-34

-------
Analyte
chloroform
carbon tetrachloride
tetrahydrofuran
1,1,1 -trichloroethane
1 , 1 -dichloropropene
1-chlorobutane
benzene
t-amyl methyl ether (TAME)
1 ,2 -dichloroethane
trichloroethene
1,4-difluorobenzene (IS #1)
t-amyl ethyl ether (TAEE)
dibromomethane
1 ,2 -dichloropropane
bromodichloro methane
cis- 1 , 3 -dichloropropene
toluene
tetrachloroethene
trans- 1 , 3 -dichloropropene
ethyl methacrylate
1 , 1 ,2-trichloroethane
dibromochloro methane
1,3 -dichloropropane
1 ,2 -dibromoethane
chlorobenzene-
-------
Analyte
1 ,2,4-trimethylbenzene
sec-butylbenzene
4-isopropyltoluene
1,3 -dichlorobenzene
l,4-dichlorobenzene-<5?4 (IS #3)
1 ,4 -dichlorobenzene
n-butylbenzene
hexachloroethane
l,2-dichlorobenzene-J4 (surrogate #3)
1 ,2-dichlorobenzene
1 ,2-dibromo-3 -chloropropane
hexachlorobutadiene
1 ,2,4-trichlorobenzene
naphthalene
1,2,3 -trichlorobenzene
Peak no. Fig.'s 2a, 2b, 2c
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
RT
12.40
12.49
12.59
12.66
12.71
12.72
12.90
13.02
13.03
13.04
13.61
14.05
14.08
14.31
14.44
Q-Ion
105
105
119
146
152
146
134
166
152
146
157
225
180
128
180
ISb Reference
3
o
J
o
J
o
J
o
J
o
J
o
J
o
J
o
J
o
J
o
J
o
J
o
J
3
3
   These quantitation ions are appropriate for the column used to generate method performance data. The user must
   verify that the quantitation ions selected for their column are unique and free from interference due to overlapping
   method analytes.
   IS = internal standard.

TABLE 5.  RETENTION TIMES, RECOMMENDED QUANTITATION IONS,
CONFIRMATION IONS, SUGGESTED INTERNAL STANDARD REFERENCES, EXAMPLE
CHROMATOGRAPHIC WINDOWS and DWELL TIMES FOR SIM MODE"
Analyte
chlorodifluoro methane
chloro methane
vinyl chloride
1,3 -butadiene
bromo methane
1,1-dichloroethene
methylene chloride
trans-l,2-dichloroethene
methyl-t-butyl ether- d3 (surrogate #1)
methyl-t-butyl ether (MtBE)
1,1-dichloroethane
cis-l,2-dichloroethene
bromochloromethane
chloroform
carbon tetrachloride
1,1,1 -trichloroethane
benzene
1 ,2 -dichloroethane
trichloroethene
Peak no. Fig.'s 5a,
5b,5c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
RT
1.87
2.03
2.09
2.10
2.39
3.18
3.87
4.07
4.20
4.22
4.94
5.68
5.96
6.05
6.22
6.31
6.79
7.06
7.54
Q-Ion
51
50
62
54
94
96
84
96
76
73
63
96
128
83
117
97
78
62
132
Confirmation
Ions
67
52
64
53
96
61,98
49
61
57
57
65
61
130
85
119
99
77
64
130, 95
ISb
Reference
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Window0
1
2
3
                                           524.4-36

-------
Analyte
1,4-difluorobenzene (IS #1)
1 ,2 -dichloropropane
bromodichloro methane
toluene
tetrachloroethene
1 , 1 ,2-trichloroethane
dibromochloro methane
1 ,2-dibromoethane
chlorobenzene-c/5 (IS #2)
chlorobenzene
ethylbenzene
1,1,1 ,2-tetrachloroethane
m-xylene
p-xylene
o-xylene
styrene
bromoform
4-bromofluorobenzene (surrogate #2)
n-propylbenzene
1,2,3 -trichloropropane
sec-butylbenzene
l,4-dichlorobenzene-
-------
Analyte
diethyl ether
1,1-dichloroethene
carbon disulfide
methyl iodide
allyl chloride
methylene chloride
trans- 1 ,2 -dichloroethene
methyl acetate
methyl-t-butyl ether (MtBE)
t-butyl alcohol (TEA)
diisopropyl ether (DIPE)
1,1-dichloroethane
t-butyl ethyl ether (ETBE)
cis- 1 ,2 -dichloroethene
bromochloro methane
chloroform
carbon tetrachloride
tetrahydrofuran
1,1,1 -trichloroethane
1 , 1 -dichloropropene
1-chlorobutane
benzene
t-amyl methyl ether (TAME)
1,2-dichloroethane
trichloroethene
t-amyl ethyl ether (TAEE)
dibromo methane
1,2-dichloropropane
bromodichloromethane
cis-l,3-dichloropropene
toluene
tetrachloroethene
trans-1 ,3 -dichloropropene
ethyl methacrylate
1, 1,2-trichloroethane
dibromochloromethane
1 , 3 -dichloropropane
1,2-dibromoethane
chlorobenzene
ethylbenzene
1,1,1,2 -tetrachloroethane
m- and p-xylene
o-xylene
styrene
bromoform
isopropylbenzene
bromobenzene
LCMRL, fig/L
0.35
0.18
0.20
0.24
0.26
0.15
0.29
0.21
0.17
0.33
0.10
0.14
0.12
0.21
0.56
0.16
0.14
0.49
0.17
0.50
0.10
0.11
0.16
0.23
0.13
0.13
0.18
0.17
0.19
0.13
0.13
0.27
0.20
0.11
0.38
0.23
0.12
0.13
0.20
0.15
0.18
0.30
0.26
0.20
0.26
0.12
0.19
DL Fortification, jig/L
0.25
0.25
0.10
0.25
0.25
0.25
0.25
0.25
0.10
0.25
0.10
0.10
0.10
0.10
0.25
0.10
0.10
0.10
0.10
0.25
0.10
0.10
0.10
0.10
0.10
0.10
0.25
0.10
0.25
0.10
0.10
0.25
0.25
0.25
0.10
0.25
0.10
0.10
0.10
0.10
0.10
0.20
0.25
0.10
0.25
0.10
0.10
DL,u/L
0.070
0.14
0.078
0.099
0.12
0.18
0.12
0.12
0.042
0.11
0.029
0.095
0.033
0.083
0.092
0.070
0.073
0.063
0.060
0.14
0.053
0.028
0.054
0.027
0.078
0.050
0.13
0.088
0.081
0.050
0.031
0.059
0.095
0.10
0.048
0.10
0.098
0.090
0.050
0.026
0.081
0.11
0.11
0.033
0.14
0.028
0.066
524.4-38

-------
Analyte
n-propylbenzene
1, 1,2,2-tetrachloroethane
2-chlorotoluene
1 , 3 ,5 -trimethylbenzene
1,2,3-trichloropropane
4-chlorotoluene
t-butylbenzene
pentachloroethane
1,2,4-trimethylbenzene
sec-butylbenzene
4-isopropyltoluene
1 , 3 -dichlorobenzene
1,4-dichlorobenzene
n-butylbenzene
hexachloroethane
1,2-dichlorobenzene
l,2-dibromo-3 -chloropropane
hexachlorobutadiene
1,2,4-trichlorobenzene
naphthalene
1,2,3 -trichlorobenzene
LCMRL, fig/L
0.18
0.15
0.26
0.12
0.42
0.23
0.25
0.29
0.18
0.24
0.16
0.20
0.19
0.30
0.62
0.14
0.44
0.34
0.15
0.14
0.16
DL Fortification, jig/L
0.10
0.10
0.10
0.10
0.25
0.10
0.25
0.25
0.10
0.10
0.10
0.10
0.10
0.10
0.25
0.10
0.25
0.10
0.10
0.10
0.10
DL,u/L
0.045
0.067
0.088
0.037
0.13
0.082
0.16
0.16
0.055
0.052
0.064
0.049
0.029
0.094
0.14
0.056
0.15
0.086
0.071
0.044
0.042
LCMRLs calculated according to the procedure in reference 1 with the following modification: Instead of
evaluating seven replicates at four concentration levels, LCMRLs are now obtained by analyzing four replicates at
seven concentration levels.
                                                524.4-39

-------
TABLE 7. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.50,
1.0 AND 10 jig/L IN REAGENT WATER FOR FULL SCAN MODE
Analyte
dichlorodifluoromethane
chlorodifluoro methane
chloro methane
vinyl chloride
1,3 -butadiene
bromo methane
trichlorofluoromethane
diethyl ether
1,1-dichloroethene
carbon disulfide
methyl iodide
allyl chloride
methylene chloride
trans-l,2-dichloroethene
methyl acetate
methyl-t-butyl ether
(MtBE)
t-butyl alcohol (TEA)
diisopropyl ether (DIPE)
1,1-dichloroethane
t-butyl ethyl ether (ETBE)
cis-l,2-dichloroethene
bromochloromethane
chloroform
carbon tetrachloride
tetrahydrofuran
1,1,1 -trichloroethane
1 , 1 -dichloropropene
1-chlorobutane
benzene
t-amyl methyl ether
(TAME)
1 ,2 -dichloroethane
trichloroethene
t-amyl ethyl ether (TAEE)
dibromomethane
1 ,2 -dichloropropane
bromodichloro methane
cis- 1 , 3 -dichloropropene
toluene
tetrachloroethene
trans- 1 , 3 -dichloropropene
ethyl methacrylate
1 , 1 ,2-trichloroethane
dibromochloro methane
1,3 -dichloropropane
1 ,2 -dibromoethane
chlorobenzene
ethylbenzene
Fortified Cone. = 0.50 jig/L
(n=7)
Mean % Recovery
77.4
127
88.8
103
107
111
105
120
108
93.6
95.5
76.1
69.2
108
88.9
97.5
45.7
90.5
89.4
91.3
84.1
93.8
90.1
83.0
86.6
79.3
99.7
91.5
81.6
98.9
105
99.6
91.4
89.0
85.1
87.3
83.9
85.6
74.3
77.4
90.9
97.6
90.7
93.0
75.1
82.6
87.1
RSDa
8.5
4.1
14
8.7
8.3
6.7
9.0
13
7.9
6.4
7.3
5.6
11
6.5
11
8.9
31
3.5
5.3
4.8
8.5
13
4.5
9.7
21
4.3
6.6
8.2
3.5
3.9
4.0
5.2
3.6
12
6.3
8.5
3.9
3.4
12
7.4
9.1
7.0
5.2
2.7
7.6
4.8
3.9
Fortified Cone. = 1.0 jig/L
(n=7)
Mean % Recovery
82.8
122
102
106
106
104
104
108
93.2
92.3
93.9
84.2
84.5
104
89.6
97.6
75.8
96.2
91.6
97.0
94.2
96.5
97.3
92.4
93.5
91.1
95.6
92.3
93.6
98.4
102
103
94.1
93.8
92.4
97.1
92.7
92.0
87.2
90.1
93.7
101
95.7
96.4
89.5
93.4
93.8
RSD
17
4.7
3.3
6.0
6.7
5.3
8.2
5.9
5.3
6.0
6.5
6.1
15
3.2
12
3.5
13
2.5
5.8
3.8
5.6
4.9
4.3
3.9
8.9
6.3
6.7
7.1
4.6
3.0
4.5
4.9
1.8
6.1
6.0
3.7
3.5
6.5
5.8
5.6
5.3
8.5
3.7
4.0
4.5
3.3
3.8
Fortified Cone. = 10 jig/L
(n=7)
Mean % Recovery
104
110
108
109
110
110
111
112
103
98.9
105
100
102
100
103
103
105
103
102
103
102
104
103
100
100
102
97.6
100
102
102
104
103
104
104
102
104
102
102
102
103
103
104
102
105
104
104
102
RSD
6.3
7.1
5.5
6.5
6.5
6.8
6.9
5.2
6.0
6.6
5.6
8.0
6.3
6.5
4.3
5.2
4.6
5.2
5.1
4.8
6.5
6.0
5.5
5.2
5.1
5.7
8.1
7.2
6.4
5.2
4.3
6.3
5.2
5.4
6.0
4.7
5.9
4.4
6.3
5.4
5.2
3.7
4.8
3.9
4.4
5.2
5.4
                                   524.4-40

-------
Analyte
1,1,1 ,2-tetrachloroethane
m- and p-xylene
o-xylene
styrene
bromoform
isopropylbenzene
bromobenzene
n-propylbenzene
1 , 1 ,2,2-tetrachloroethane
2-chlorotoluene
1,3,5 -trimethy Ibenzene
1,2,3 -trichloropropane
4-chlorotoluene
t-buty Ibenzene
pentachloroethane
1 ,2, 4-trimethy Ibenzene
sec-butylbenzene
4-isopropyltoluene
1,3 -dichlorobenzene
1 ,4 -dichlorobenzene
n-butylbenzene
hexachloroethane
1 ,2 -dichlorobenzene
l,2-dibromo-3-
chloropropane
hexachlorobutadiene
1 ,2,4-trichlorobenzene
naphthalene
1,2,3 -trichlorobenzene
Fortified Cone. = 0.50 jig/L
(n=7)
Mean % Recovery
83.0
82.6
77.3
88.2
80.6
83.1
91.9
89.7
96.2
95.0
87.4
84.2
83.2
86.9
87.6
87.0
81.4
84.5
84.5
86.6
73.5
81.1
83.0
80.5
64.2
90.7
88.0
86.8
RSDa
5.9
7.0
5.6
8.1
6.8
2.8
4.1
4.1
8.3
5.2
4.4
7.6
4.4
8.7
12
5.0
3.6
5.9
5.9
4.2
6.8
16
6.2
10
6.0
5.3
2.9
8.7
Fortified Cone. = 1.0 jig/L
(n=7)
Mean % Recovery
94.1
93.3
94.3
95.3
91.0
93.6
96.8
96.3
97.9
98.2
94.9
92.9
94.2
92.4
89.9
94.1
93.3
95.5
92.2
97.2
93.0
94.7
96.6
90.9
85.7
91.9
94.0
92.4
RSD
3.6
2.9
2.7
o o
J.J
3.9
3.0
5.0
2.1
4.6
2.2
1.8
8.4
1.3
6.9
5.8
1.8
3.6
2.4
2.0
o o
J.J
5.0
5.3
3.4
7.1
6.6
2.1
3.2
4.0
Fortified Cone. = 10 jig/L
(n=7)
Mean % Recovery
104
102
103
102
103
103
102
100
102
100
102
102
100
102
100
101
101
102
100
102
103
102
103
103
100
100
102
101
RSD
5.1
4.5
5.6
5.3
6.2
5.3
5.7
6.1
5.4
6.2
5.8
6.6
5.7
6.0
5.8
6.0
6.1
6.6
5.9
5.7
6.2
6.1
5.6
5.7
6.9
5.2
5.7
5.5
RSD = relative standard deviation.
                                               524.4-41

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TABLE 8. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.50,
1.0 AND 10 jig/L IN DRINKING WATER FROM A GROUND WATER SOURCE" FOR FULL
SCAN MODE
Analyte
dichlorodifluoromethane
chlorodifluoro methane
chloro methane
vinyl chloride
1,3 -butadiene
bromo methane
trichlorofluoromethane
diethyl ether
1,1-dichloroethene
carbon disulfide
methyl iodide
allyl chloride
methylene chloride
trans-l,2-dichloroethene
methyl acetate
methyl-t-butyl ether
(MtBE)
t-butyl alcohol (TEA)
diisopropyl ether (DIPE)
1,1-dichloroethane
t-butyl ethyl ether (ETBE)
cis-l,2-dichloroethene
bromochloromethane
chloroform
carbon tetrachloride
tetrahydrofuran
1,1,1 -trichloroethane
1 , 1 -dichloropropene
1-chlorobutane
benzene
t-amyl methyl ether
(TAME)
1 ,2 -dichloroethane
trichloroethene
t-amyl ethyl ether (TAEE)
dibromomethane
1 ,2 -dichloropropane
bromodichloro methane
cis- 1 , 3 -dichloropropene
toluene
tetrachloroethene
trans- 1 , 3 -dichloropropene
ethyl methacrylate
1 , 1 ,2-trichloroethane
dibromochloro methane
1,3 -dichloropropane
1 ,2 -dibromoethane
Native
Cone., (o,g/L
(n=3)
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.39
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
3.48
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
5.09
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
6.08
N.D.
N.D.
Fortified Cone. = 0.50
fig/L (n=7)
Mean %
Recovery1"
112
80.7
90.7
98.9
66.1
115
101
101
89.6
88.8
81.0
92.0
73.7
82.2
96.5
80.6
92.3
95.3
86.0
81.4
87.3
101
(i
71.0
127
90.2
100
94.7
84.5
97.3
95.2
83.6
89.0
89.0
85.5
78.4"
90.1
91.1
93.5
82.4
94.0
100
(i
87.2
99.0
RSDC
2.8
8.9
4.5
6.9
16
7.3
5.4
5.6
11
8.7
18
13
10
19
7.3
12
9.7
3.6
10
5.7
9.4
9.5
3.5
8.4
8.3
8.5
6.6
9.1
7.3
4.2
7.4
6.8
8.8
12
7.2
1.5
6.7
5.8
12
6.4
8.8
7.0
1.8
5.1
8.0
Fortified Cone. = 1.0
fig/L (n=7)
Mean %
Recovery1"
95.0
91.4
92.3
97.3
84.3
115
101
103
91.1
93.7
81.6
99.2
97.8
91.2
86.9
86.2
97.9
97.8
93.9
91.2
94.8
104
(i
86.2
128.5
98.7
97.4
98.9
93.0
92.3
103
91.9
96.4
96.4
93.9
75.5"
94.7
94.3
95.3
92.0
91.9
98.5
(i
93.0
98.8
RSD
5.6
6.8
9.2
5.0
5.9
8.4
5.8
9.0
12
5.4
11
12
11
8.2
15
5.1
9.4
7.4
5.7
3.3
4.3
7.0
1.9
10
4.4
5.5
8.2
4.7
4.7
8.7
7.1
6.3
5.4
7.6
6.8
1.5
7.7
4.9
11
11
8.3
8.5
3.5
8.1
9.1
Fortified Cone. = 10
fig/L (n=7)
Mean %
Recovery1"
104
105
105
103
101
127
103
103
97.8
99.9
105
96.7
100
102
98.6
97.9
91.3
98.9
99.8
98.1
97.1
97.2
97.4
98.7
98.3
99.9
99.6
101
98.6
94.5
99.6
98.3
96.3
97.5
96.4
97.4
95.1
97.7
97.3
95.8
94.4
96.0
97.6
96.3
95.8
RSD
4.1
4.5
2.5
3.2
4.0
10
3.6
1.4
3.1
2.5
8.5
4.6
3.4
3.4
2.1
1.5
2.0
1.9
2.9
2.2
2.5
3.3
1.7
0.87
2.7
2.8
3.3
3.2
2.6
2.4
2.3
2.7
1.7
2.1
1.6
1.9
1.4
1.8
2.9
3.2
1.7
2.7
1.4
2.5
3.1
                                   524.4-42

-------
Analyte
chlorobenzene
ethylbenzene
1,1,1 ,2-tetrachloroethane
m- and p-xylene
o-xylene
styrene
bromoform
isopropylbenzene
bromobenzene
n-propylbenzene
1 , 1 ,2,2-tetrachloroethane
2-chlorotoluene
1,3,5 -trimethy Ibenzene
1,2,3 -trichloropropane
4-chlorotoluene
t-buty Ibenzene
pentachloroethane
1 ,2, 4-trimethy Ibenzene
sec-butylbenzene
4-isopropyltoluene
1,3 -dichlorobenzene
1 ,4 -dichlorobenzene
n-butylbenzene
hexachloroethane
1 ,2 -dichlorobenzene
l,2-dibromo-3-
chloropropane
hexachlorobutadiene
1 ,2,4-trichlorobenzene
naphthalene
1,2,3 -trichlorobenzene
Native
Cone., (o,g/L
(n=3)
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
2.17
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
Fortified Cone. = 0.50
fig/L (n=7)
Mean %
Recovery1"
89.3
84.8
90.9
92.6
93.7
88.3
(i
85.9
78.2
85.9
96.4
83.3
85.4
92.5
84.5
76.7
97.6
90.9
85.9
85.1
88.6
86.5
87.0
99.5
89.6
92.2
80.8
82.1
95.4
101
RSDC
2.5
8.9
7.2
5.6
5.5
6.6
4.5
3.6
11
5.0
6.8
4.8
5.1
10
6.1
11
7.7
4.9
1.8
5.6
4.5
2.9
3.6
15
7.1
13
6.1
3.3
4.1
5.0
Fortified Cone. = 1.0
fig/L (n=7)
Mean %
Recovery1"
96.0
92.5
94.9
94.0
99.1
90.5
(i
93.7
94.0
96.2
99.2
93.8
95.9
96.8
93.1
89.8
99.8
98.0
97.6
97.0
98.0
94.9
95.8
103
95.6
95.8
91.7
92.1
93.2
95.6
RSD
6.0
7.4
7.9
4.7
8.2
3.5
4.5
5.6
6.4
7.3
7.2
8.1
6.3
10
8.6
6.5
6.3
5.5
4.7
4.7
7.0
7.3
5.9
10
7.0
5.3
6.8
6.0
5.2
6.8
Fortified Cone. = 10
fig/L (n=7)
Mean %
Recovery1"
94.8
97.6
94.5
96.7
96.8
96.0
92.1
98.2
92.7
96.9
92.6
93.2
96.6
93.3
93.6
97.6
93.8
95.8
97.3
96.7
93.6
92.7
95.2
97.6
92.9
92.5
94.8
92.5
92.8
91.4
RSD
1.4
1.2
1.6
1.6
2.4
2.1
2.6
1.8
2.5
3.6
1.8
2.9
3.4
2.9
2.5
4.1
3.1
3.1
3.3
3.4
2.0
2.3
3.1
4.4
2.4
2.6
3.6
2.5
2.0
2.6
Ground water physical parameters:  pH = 7.61; hardness = 350 milligrams/liter (mg/L) (as CaCO3); free chlorine =
0.77 mg/L.
Recoveries corrected for native levels in the unfortified matrix.
RSD = relative standard deviation.
Fortified at less than 1A the concentration in the native matrix.
                                                524.4-43

-------
TABLE 9. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.50,
1.0 AND 10 jig/L IN DRINKING WATER FROM A SURFACE WATER SOURCE" FOR FULL
SCAN MODE
Analyte
dichlorodifluoromethane
chlorodifluoro methane
chloro methane
vinyl chloride
1,3 -butadiene
bromo methane
trichlorofluoromethane
diethyl ether
1,1-dichloroethene
carbon disulfide
methyl iodide
allyl chloride
methylene chloride
trans-l,2-dichloroethene
methyl acetate
methyl-t-butyl ether
(MtBE)
t-butyl alcohol (TEA)
diisopropyl ether (DIPE)
1,1-dichloroethane
t-butyl ethyl ether (ETBE)
cis-l,2-dichloroethene
bromochloromethane
chloroform
carbon tetrachloride
tetrahydrofuran
1,1,1 -trichloroethane
1 , 1 -dichloropropene
1-chlorobutane
benzene
t-amyl methyl ether
(TAME)
1 ,2 -dichloroethane
trichloroethene
t-amyl ethyl ether (TAEE)
dibromomethane
1 ,2 -dichloropropane
bromodichloro methane
cis- 1 , 3 -dichloropropene
toluene
tetrachloroethene
trans- 1 , 3 -dichloropropene
ethyl methacrylate
1 , 1 ,2-trichloroethane
dibromochloro methane
1,3 -dichloropropane
1 ,2 -dibromoethane
Native
Cone., (J,g/L
(n=3)
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
19.4
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
20.3
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
16.1
N.D.
N.D.
Fortified Cone. = 0.50
fig/L (n=7)
Mean %
Recovery1"
90.5
102
96.7
104
109
108
94.4
104
97.9
94.6
85.1
104
104
100
110
87.0
91.8
85.5
95.1
84.2
97.3
90.8
(i
86.0
84.5
84.9
92.6
92.3
94.6
80.8
94.7
89.4
59.5
91.4
86.3
(i
97.1
82.5
80.3
91.3
84.4
79.8
(i
87.6
80.8
RSDC
10
9.9
7.1
6.3
5.5
8.5
4.8
8.3
10
5.9
7.5
9.4
9.1
11
8.6
9.3
7.6
4.0
5.1
4.1
5.5
16
2.0
8.6
14
7.5
15
8.7
7.8
9.8
8.7
10
7.1
7.9
7.3
1.6
8.3
6.7
7.1
7.1
5.1
11
1.3
8.5
4.9
Fortified Cone. = 1.0
fig/L (n=7)
Mean %
Recovery1"
90.7
97.3
94.0
105
97.9
104
94.7
104
97.7
93.7
86.3
92.9
102
89.8
104
91.9
99.7
90.4
92.4
87.6
96.6
98.3
(i
89.4
97.7
89.3
90.5
91.0
96.2
88.8
90.8
90.5
83.1
93.6
90.9
(i
93.1
86.1
83.5
92.3
89.5
88.0
(i
91.6
83.9
RSD
3.7
5.3
6.4
4.5
8.7
9.1
4.7
4.7
6.8
7.2
6.0
4.0
6.1
12
9.4
4.0
4.6
5.7
4.3
3.6
7.5
8.3
6.1
5.1
6.5
7.2
4.2
7.9
4.6
8.7
3.5
7.1
3.4
7.1
7.6
3.4
6.5
4.4
5.9
5.1
4.5
8.5
3.0
4.3
5.6
Fortified Cone. = 10
fig/L (n=7)
Mean %
Recovery1"
103
105
102
106
104
116
106
104
98.2
99.7
95.2
96.3
102
97.7
107
99.5
107
100
98.9
99.4
101
103
86.0
101
103
97.7
96.3
99.3
99.4
100
99.8
99.2
104
99.5
99.3
87.4
98.6
97.5
93.6
97.2
98.3
101
99.6
98.5
97.7
RSD
2.8
3.1
3.0
3.1
3.0
5.3
2.9
3.7
3.2
2.3
3.2
3.7
2.2
3.0
2.8
2.9
3.0
2.2
3.2
2.0
2.5
2.1
2.2
1.4
2.7
2.9
4.6
2.2
2.1
2.6
1.8
1.9
2.3
2.9
2.1
2.4
2.1
1.9
1.5
3.9
2.5
1.0
2.7
2.3
3.0
                                  524.4-44

-------
Analyte
chlorobenzene
ethylbenzene
1,1,1 ,2-tetrachloroethane
m- and p-xylene
o-xylene
styrene
bromoform
isopropylbenzene
bromobenzene
n-propylbenzene
1 , 1 ,2,2-tetrachloroethane
2-chlorotoluene
1,3,5 -trimethy Ibenzene
1,2,3 -trichloropropane
4-chlorotoluene
t-buty Ibenzene
pentachloroethane
1 ,2, 4-trimethy Ibenzene
sec-butylbenzene
4-isopropyltoluene
1,3 -dichlorobenzene
1 ,4 -dichlorobenzene
n-butylbenzene
hexachloroethane
1 ,2 -dichlorobenzene
l,2-dibromo-3-
chloropropane
hexachlorobutadiene
1 ,2,4-trichlorobenzene
naphthalene
1,2,3 -trichlorobenzene
Native
Cone., ng/L
(n=3)
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
3.63
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
Fortified Cone. = 0.50
fig/L (n=7)
Mean %
Recovery1"
73.9
79.8
75.5
80.1
75.6
82.3
(i
73.6
79.0
64.9
74.1
81.7
74.3
86.3
69.9
69.4
72.0
77.8
64.5
64.0
77.3
70.5
69.4
89.3
71.3
73.2
59.2
70.9
68.3
72.3
RSDC
6.6
4.9
6.2
4.2
7.2
7.0
3.5
6.0
11
6.9
8.0
6.2
8.4
8.0
11
13
10
4.8
5.5
3.8
10
4.2
12
14
5.5
11
14
8.2
4.5
10
Fortified Cone. = 1.0
fig/L (n=7)
Mean %
Recovery1"
86.0
84.7
83.3
86.8
81.0
89.2
(i
82.4
86.1
82.2
86.3
86.0
85.5
87.4
79.7
84.8
84.3
86.0
80.7
79.6
84.4
86.2
80.9
93.3
82.4
87.8
75.7
83.2
83.1
82.8
RSD
3.1
4.6
5.9
3.3
4.3
3.2
4.0
5.7
7.5
3.6
4.7
4.1
4.1
7.7
5.8
9.1
8.2
6.1
5.7
6.9
8.8
5.5
9.5
10
5.5
8.6
8.4
3.0
6.0
4.6
Fortified Cone. = 10
fig/L (n=7)
Mean %
Recovery1"
97.2
96.3
95.9
98.3
97.0
96.5
96.0
97.7
95.7
97.0
96.9
95.8
97.8
96.6
97.2
97.4
96.4
97.8
99.1
98.4
97.3
97.4
99.1
99.7
97.3
95.9
98.5
97.0
101
97.0
RSD
2.1
2.2
3.8
2.0
1.3
2.7
2.4
2.1
3.7
3.1
4.6
2.8
3.2
5.1
2.8
4.1
3.7
2.9
2.6
2.8
2.5
2.4
3.7
2.9
4.1
4.0
3.6
3.6
4.5
5.1
Surface water physical parameters:  pH = 7.20; hardness = 152 milligrams/liter (mg/L) (as CaCO3); free chlorine =
1.85 mg/L.
Recoveries corrected for native levels in the unfortified matrix.
RSD = relative standard deviation.
Fortified at less than !/2 the concentration in the native matrix.
                                                524.4-45

-------
TABLE 10.  LOWEST CONCENTRATION MINIMUM REPORTING LEVELS (LCMRLs)
AND DETECTION LIMITS (DLs) FOR SIM MODE3
Analyte
chlorodifluoro methane
chloro methane
vinyl chloride
1,3 -butadiene
bromo methane
1,1-dichloroethene
methylene chloride
trans-l,2-dichloroethene
methyl-t-butyl ether (MtBE)
1,1-dichloroethane
cis-l,2-dichloroethene
bromochloromethane
chloroform
carbon tetrachloride
1,1,1 -trichloroethane
benzene
1 ,2-dichloroethane
trichloroethene
1 ,2 -dichloropropane
bromodichloro methane
toluene
tetrachloroethene
1 , 1 ,2-trichloroethane
dibromochloro methane
1 ,2-dibromoethane
chlorobenzene
ethylbenzene
1,1,1 ,2-tetrachloroethane
m-xylene and p-xylene
o-xylene
styrene
bromoform
n-propylbenzene
1,2,3 -trichloropropane
sec-butylbenzene
1 ,4-dichlorobenzene
1 ,2 -dichlorobenzene
1 ,2 -dibromo-3 -chloropropane
1 ,2,4-trichlorobenzene
LCMRL, fig/L
0.027
DL Fortification, jig/L
0.025
DL,u/L
0.006
Not determined: significant background levels from trap materials (See Section 4.3.4)
0.048
0.028
0.025
0.025
0.007
0.008
Not determined: significant background levels from trap materials (See Section 4.3.4)
0.061
0.050
0.009
Not determined: significant background levels from ambient sources
0.028
0.012
0.011
0.040
0.060
0.032
0.033
0.039
0.022
0.029
0.037
0.043
0.027
0.034
0.025
0.029
0.016
0.048
0.036
0.013
0.059
0.17
0.037
0.018
0.021
0.022
0.033
0.019
0.026
0.025
0.069
0.030
0.025
0.025
0.025
0.040
0.040
0.025
0.025
0.025
0.025
0.025
0.025
0.040
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.025
0.040
0.025
0.025
0.025
0.040
0.025
0.014
0.009
0.007
0.037
0.013
0.015
0.008
0.009
0.012
0.012
0.012
0.011
0.011
0.009
0.011
0.010
0.006
0.023
0.009
0.009
0.011
0.020
0.016
0.012
0.008
0.010
0.028
0.011
0.012
0.013
0.033
0.013
   LCMRLs calculated according to the procedure in reference 1 with the following modification:
   evaluating seven replicates at four concentration levels, LCMRLs are now obtained by analyzinj
   seven concentration levels.
                                             524.4-46
Instead of
I four replicates at

-------
TABLE 11.  SAMPLE HOLDING TIME DATA FOR METHOD ANALYTES FORTIFIED AT
20 jig/L IN A CHLORINATED SURFACE WATER3 (n=3 SAMPLES)

Analyte
dichlorodifluoromethane
chlorodifluoro methane
chloro methane
vinyl chloride
1,3 -butadiene
bromo methane
trichlorofluoromethane
diethyl ether
1,1-dichloroethene
carbon disulfide
methyl iodide
allyl chloride
methylene chloride
trans-l,2-dichloroethene
methyl acetate
methyl-t-butyl ether (MtBE)
t-butyl alcohol (TEA)
diisopropyl ether (DIPE)
1,1-dichloroethane
t-butyl ethyl ether (ETBE)
cis-l,2-dichloroethene
bromochloromethane
chloroform
carbon tetrachloride
tetrahydrofuran
1,1,1 -trichloroethane
1 , 1 -dichloropropene
1-chlorobutane
benzene
t-amyl methyl ether (TAME)
1 ,2 -dichloroethane
trichloroethene
t-amyl ethyl ether (TAEE)
dibromomethane
1 ,2 -dichloropropane
bromodichloro methane
cis- 1 , 3 -dichloropropene
toluene
tetrachloroethene
trans- 1 , 3 -dichloropropene
ethyl methacrylate
1 , 1 ,2-trichloroethane
dibromochloro methane
1,3 -dichloropropane
1 ,2 -dibromoethane
chlorobenzene
ethylbenzene
1,1,1,2 -tetrachloroethane
m- and p-xylene
DayO
Mean %
Recovery
110
112
114
117
116
117
114
110
106
108
106
108
106
107
105
104
105
107
109
105
106
104
102
108
102
109
110
114
108
105
108
105
107
106
108
105
106
109
110
106
108
105
104
108
104
108
115
106
114

RSDb
2.2
2.0
0.88
0.99
1.3
6.9
0.54
1.2
0.94
0.58
1.3
0.57
0.17
0.89
3.4
0.92
3.2
0.71
1.0
0.30
0.66
0.64
0.56
1.4
1.4
0.70
0.24
0.25
0.63
0.56
2.1
0.28
0.31
1.5
0.48
0.85
0.33
1.3
2.4
1.9
1.4
1.8
0.99
1.0
1.7
1.4
1.1
1.6
1.3
Day 7
Mean %
Recovery
107
109
110
113
106
116
116
106
107
106
106
100
106
103
101
101
104
109
108
107
105
104
100
109
98.4
109
107
111
106
107
105
105
108
105
106
104
98.5
108
106
99.1
104
103
104
104
104
106
110
106
110

RSD
2.5
0.63
1.1
1.6
1.9
3.5
2.9
1.5
0.62
1.9
0.33
0.73
0.55
1.8
0.32
0.049
2.9
0.72
0.82
0.53
0.67
1.4
0.91
.2
.5
089
.5
.1
.2
0.45
0.59
0.85
0.73
0.42
0.21
1.2
1.0
0.46
1.1
0.94
0.56
0.93
0.98
0.10
1.3
0.36
0.33
0.35
0.70
Day 14
Mean %
Recovery
111
107
112
116
105
114
117
113
111
107
101
101
108
107
83.2
105
105
109
111
107
108
105
107
116
101
115
108
115
109
107
108
107
107
107
109
109
96.7
110
111
96.4
105
106
107
106
106
109
116
110
114

RSD
3.9
0.87
2.0
0.87
4.6
2.5
2.4
1.0
2.3
3.0
0.93
1.0
0.92
1.5
4.0
0.79
1.8
0.65
0.74
0.89
0.71
0.45
0.97
2.2
1.7
0.94
1.5
0.90
0.57
0.59
1.2
0.16
0.69
0.33
0.78
1.2
1.2
1.2
2.7
0.30
1.5
2.1
0.98
1.2
0.72
1.1
1.4
0.92
2.3
                                  524.4-47

-------

Analyte
o-xylene
styrene
bromoform
isopropylbenzene
bromobenzene
n-propylbenzene
1 , 1 ,2,2-tetrachloroethane
2-chlorotoluene
1,3,5 -trimethy Ibenzene
1,2,3 -trichloropropane
4-chlorotoluene
t-buty Ibenzene
pentachloroethane
1 ,2,4-trimethy Ibenzene
sec-butylbenzene
4-isopropyltoluene
1,3 -dichlorobenzene
1 ,4 -dichlorobenzene
n-butylbenzene
hexachloroethane
1 ,2 -dichlorobenzene
l,2-dibromo-3-
chloropropane
hexachlorobutadiene
1 ,2,4-trichlorobenzene
naphthalene
1,2,3 -trichlorobenzene
DayO
Mean %
Recovery
113
111
103
118
109
122
108
115
121
106
113
123
109
120
125
123
113
113
122
123
111
105
122
114
112
114

RSDb
0.83
1.3
1.8
1.2
0.38
1.3
0.63
0.65
1.2
1.6
4.1
0.84
2.2
0.99
1.5
1.3
0.85
1.1
1.3
0.42
0.82
1.9
2.5
1.3
0.77
0.53
Day 7
Mean %
Recovery
109
106
101
114
104
111
100
107
111
102
106
115
103
110
115
112
105
104
106
115
104
99.1
112
102
103
103

RSD
0.87
0.62
1.7
0.81
1.9
2.0
.5
.9
.4
2.5
.8
.3
3.0
2.0
1.8
2.4
1.7
2.0
3.6
0.82
1.7
1.9
3.6
2.3
1.0
1.7
Day 14
Mean %
Recovery
115
108
108
123
107
119
103
112
120
102
110
129
112
118
129
123
109
107
111
132
108
103
124
105
107
108

RSD
0.79
1.7
1.5
1.5
1.8
2.1
0.83
2.1
1.7
1.4
2.0
0.38
0.47
1.5
1.9
2.6
1.5
1.7
6.5
1.6
1.0
2.4
2.1
3.0
2.1
2.0
Surface water physical parameters: pH = 7.43; hardness = 154 milligrams/liter (mg/L) (as CaCO3); free chlorine =
2.7 mg/L; total chlorine = 3.7 mg/L.
RSD = relative percent deviation.
                                                524.4-48

-------
TABLE 12. INITIAL DEMONSTRATION OF CAPABILITY (IDC) QUALITY CONTROL
REQUIREMENTS
Method
Reference
Section
9.2.1
Section
9.2.1
Section
9.2.2
Section
9.2.3
Section
9.2.4
Section
9.2.5
Requirement
Demonstration of
low system
background
Test for system
carryover
Demonstration of
precision
Demonstration of
accuracy
MRL confirmation
Quality Control
Sample (QCS)
Specification and Frequency
Analyze a Laboratory Reagent Blank
(LRB) prior to any other IDC steps.
Analyze a LRB after the high calibration
standard during the IDC calibration.
Analyze 7 replicate Laboratory Fortified
Blanks (LFBs) fortified near the
midrange concentration.
Calculate average recovery for replicates
used in Section 9.2.2.
Fortify and analyze 7 replicate LFBs at
the proposed MRL concentration.
Confirm that the Upper Prediction
Interval of Results (PIR) and Lower PIR
(Sect. 9.2.4.2) meet the recovery criteria.
Analyze mid-level QCS.
Acceptance Criteria
Demonstrate that all method analytes are
50%
Results must be within +30% of the true
value.
                                   524.4-49

-------
 TABLE 13. ONGOING QUALITY CONTROL REQUIREMENTS
Method
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Section
10.1
Initial calibration
Use the internal standard calibration
technique to generate a linear or
quadratic calibration curve. Use at
least 7 standard concentrations.
Validate the calibration curve as
described in Section 10.1.10.
When each calibration standard is
calculated as an unknown using the
calibration curve, the lowest level
standard must be within +50% of the
true value.  All other points must be
within +30% of the true value.
Section
9.3.1
Laboratory Reagent
Blank (LRB)
Analyze one LRB with each Analysis
Batch.
Demonstrate that all method analytes
are below 1A the Minimum Reporting
Level (MRL) and that possible
interference from reagents and
glassware do not prevent identification
and quantitation of method analytes.
Section
10.2
Continuing Calibra-
tion Check (CCC)
Verify initial calibration by analyzing
a low-level CCC at the beginning of
each Analysis Batch.  Subsequent
CCCs are required after every 10 field
samples and after the last field sample
in a batch.
The lowest level CCC must be within
+50% of the true value. All other
points must be within +30% of the
true value.

Results for field samples that are not
bracketed by acceptable CCCs are
invalid.
Section
9.3.5
Internal standard (IS)
Internal standards are added to all
standards and samples.
Peak area counts for each IS must be
within +30% of the area in the most
recent CCC and +50% of the average
peak area in the initial calibration.
Section
9.3.6
Surrogate analytes
Surrogates are added to all field
samples and QC samples prior to
analysis.
70% to 130% recovery
Section
9.3.7
Laboratory Fortified
Sample Matrix
(LFSM)
Analyze one LFSM per Analysis
Batch.  Fortify the LFSM with
method analytes at a concentration
close to but greater than the native
concentrations (if known).
For analytes fortified at concentrations
<2 x the MRL, the result must be
within+50% of the true value. All
other analytes must be within +30% of
the true value.
Section
9.3.8
Laboratory Fortified
Sample Matrix Dup-
licate (LFSMD) or
Field Duplicate (FD)
Analyze at least one LFSMD or FD
with each Analysis Batch.
For LFSMDs or FDs, relative percent
differences must be <30% (<50% if
concentration <2 x the MRL.).
Section
9.3.9
Field Reagent Blank
(FRB)
Analyze FRB if method analytes are
detected in field samples (except
disinfection byproducts).
Qualify results of any analyte detected
in both field samples and the FRB.
Section
9.3.10
Quality Control
Sample (QCS)
Analyze mid-level QCS at least
quarterly.
Results must be +30% of the true
value.
                                                 524.4-50

-------
Abundance

   30000 -




   25000 -




   20000 -




   15000-




   10000-




    5000-
                           Ion 85.00 (84.70 to 85.70): X1109019.0
                           Ion 51.001(50.70 to 51.70): X1109019.D
                                      9.70 to 50.70): X1109019.D
                                      1.70to62.70):X1109019.D
                                    33.70 to 54.70): XII09019.0
                                    93.70 to 94.70): X1109019.D
     Ion 50.0
     Ion 62J
     Ion 54.0
     Ion 94.i
Time-->  1.60
1.80
2.00
2.20
2.40
2.60
Figure 1.  Mass chromatograms of "gases" in full scan mode @ 10 ug/L.
                                                                 524.4-51

-------
Abundance

  240000
Time-->
               2.00
3.00
4.00
5.00
6.00
7.00
Figure 2a.   Reconstructed total ion chromatogram full scan mode: 10-(j,g/L procedural calibration standard.  See Table 4 for peak
            number to peak name cross reference.
                                                           524.4-52

-------
Abundance
  300000
  800000
  700000
  600000
  500000
  400000
  300000
  200000
  100000
Time-->
7.50
8.00
8.50
9.00
9.50
10.00
10.50
Figure 2b.   Reconstructed total ion chromatogram full scan mode: 10-(j,g/L procedural calibration standard.  See Table 4 for peak
             number to peak name cross reference.
                                                            524.4-53

-------
Abundance

  750000

  700000

  650000

  600000

  550000

  500000

  450000

  400000

  350000

  300000

  250000

  200000

  150000

  100000

   50000


Time->
 55,56
54
                                                                                       81
                                                                        82
                                                                                   V^VW^Viwft-'
     11.50
12.00
12.50
13.00
13.50
14.00
14.50
Figure 2c.   Reconstructed total ion chromatogram full scan mode: 10-(ig/L procedural calibration standard. See Table 4 for peak
            number to peak name cross reference.
                                                            524.4-54

-------
Abundance




   700000




   650000




   600000





   550000




   500000




   450000




   400000




   350000




   300000





   250000




   200000




   150000




   100000




    50000







Time>
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
Figure 3. Reconstructed total ion chromatogram full scan mode: method analytes fortified into drinking water @ 10 (J,g/L.
                                                               524.4-55

-------
Abundance

     5500


     5000


     4500


     4000


     3500


     3000


     2500


     2000


     1500


     1000


      500
        0
       Ion 51.00 (50.70 to 51.70): X9021002.D
       Ion 50.40 (49.70to 50.70): X9021002.D
       Ion 62.100(61.70 to 62.70): X9021002.D
       Ion 54.00 (53.70 to 54.70): X9021002.D
       Ion 94 .PD (93.70 to 94.70): X9021002.D
Time-->
2.00
2.20
2.40
2.60
Figure 4.  Mass chromatograms of "gases" in SIM mode @ 1.0 jig/L.
                                                                  524.4-56

-------
Abundance

   20000


   18000


   16000


   14000


   12000


   10000


    8000


    6000


    4000


    2000
3,4
                                                                                     16
                                                                                               17
                                                                                                    18
Time-->
              2.00
                  3.00
4.00
5.00
6.00
Figure 5a.  Reconstructed total ion chromatogram SIM mode: 1.0-(j,g/L procedural calibration standard. See Table 5 for peak
           number to peak name cross reference.
                                                           524.4-57

-------
Abundance
   30000 -
   25000 -
   20000 -
   15000-
   10000-
    5000-
                                   21
                                      22
                                                                              24   25  26
                                                                                           32,33
                                                                                                            30
Time-->
7.50
                              8.00
8.50
9.00
9.50
10.00
10.50
11.00
Figure 5b. Reconstructed total ion chromatogram SIM mode: 1.0-(ig/L procedural calibration standard. See Table 5 for peak
          number to peak name cross reference.
                                                         524.4-58

-------
Abundance

   22000


   20000


   18000


   16000


   14000


   12000


   10000


    8000


    6000


    4000


    2000
Time-->
12.00
13.00
14.00
15.00
Figure 5c.  Reconstructed total ion chromatogram SIM mode: 1.0-(j,g/L procedural calibration standard. See Table 5 for peak
           number to peak name cross reference.
                                                           524.4-59

-------