METHOD 526.     DETERMINATION OF SELECTED SEMIVOLATILE ORGANIC
                 COMPOUNDS IN DRINKING WATER BY SOLID PHASE EXTRACTION
                 AND CAPILLARY COLUMN GAS CHROMATOGRAPHY/ MASS
                 SPECTROMETRY (GC/MS)
                                  Revision 1.0
 S.D. Winslow, B. Prakash, M.M. Domino, and B.V. Pepich (IT Corporation) - June 2000

D. J. Munch (U.S. EPA, Office of Ground Water and Drinking Water)
                NATIONAL EXPOSURE RESEARCH LABORATORY
                   OFFICE OF RESEARCH AND DEVELOPMENT
                  U.S. ENVIRONMENTAL PROTECTION AGENCY
                            CINCINNATI, OHIO 45268
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                                       METHOD 526

     DETERMINATION OF SELECTED SEMIVOLATILE ORGANIC COMPOUNDS IN
 DRINKING WATER BY SOLID PHASE EXTRACTION AND CAPILLARY COLUMN GAS
                 CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
1.     SCOPE AND APPLICATION

      1.1    This is a gas chromatography/mass spectrometry (GC/MS) method for the determination
             of selected semivolatile organic compounds in raw and finished drinking waters. This
             method is applicable to the organic compounds listed below, which are efficiently
             extracted from water using a polystyrene divinylbenzene solid phase sorbent, and are
             sufficiently volatile and thermally stable for gas chromatography.  Accuracy, precision,
             and method detection limit (MDL) data have been generated in reagent water, finished
             ground and surface water for the following compounds:

                                          Chemical Abstract Services
                 Analyte                      Registry Number

                 Acetochlor                     34256-82-1

                 Cyanazine                      21725-46-2

                 Diazinon                       61790-53-2

                 2,4-Dichlorophenol                120-83-2

                 1,2-Diphenylhydrazine             122-66-7

                 Disulfoton                        298-04-4

                 Fonofos                          944-22-9

                 Nitrobenzene                      98-95-3

                 Prometon                         1610-18-0

                 Terbufos                        13071-79-9

                 2,4,6-Trichlorophenol               88-06-2

      1.2    MDLs are compound, instrument, and matrix dependent. The MDL is defined as the
             statistically calculated minimum concentration that can be measured with 99%
             confidence that the reported value is greater than zero.(1) Experimentally determined
             MDLs for the above listed analytes are provided in Section 17, Table 3. The MDL differs
             from,  and is lower than, the minimum reporting limit (MRL) (Sect. 3.17). Precision and
             accuracy were evaluated at 0.5 and 20 ug/L. Precision and accuracy data and sample


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             holding time data are presented Section 17, Tables 4 through 8. Analyte retention times
             are in Section 17, Table 2.

       1.3    This method is restricted to use by or under the supervision of analysts skilled in solid-
             phase extractions (SPE) and GC/MS analysis.

2.      SUMMARY OF METHOD

       2.1    A 1 liter water sample is passed through a SPE disk or cartridge containing
             polystyrenedivinylbenzene (SDVB) to extract the target analytes and surrogate
             compounds. The extract is dried by passing through a column of anhydrous sodium
             sulfate and is concentrated by blowdown with nitrogen to a volume of about 0.7 mL.
             Internal standards are added and the extract is diluted to a final volume of 1 mL.
             Components are separated chromatographically by injecting an aliquot of the extract onto
             a gas chromatograph equipped with a high resolution fused silica capillary column.  The
             analytes pass from the capillary column into a mass spectrometer where the they are
             identified by comparing their measured mass spectra and retention times to reference
             spectra and retention times collected for the same compounds. Instrument specific
             reference spectra and retention times for analytes are obtained by the analyses of
             calibration standards under the same GC/MS conditions used for samples. The
             concentration of each identified component is measured by relating the MS response of
             the compound's quantitation ion to the internal standard's quantitation ion MS response.

3.      DEFINITIONS

       3.1    EXTRACTION BATCH - A set of up to 20 field samples (not including QC samples)
             extracted together by the same person(s) during a work day using the same lot of solid
             phase extraction devices, solvents, surrogate solution, and fortifying solutions. Required
             QC samples include Laboratory Reagent Blank, Laboratory Fortified Blank, Laboratory
             Fortified Matrix, and either a Field Duplicate or Laboratory Fortified Matrix Duplicate.

       3.2    ANALYSIS BATCH - A set of samples that is analyzed on the same instrument during a
             24-hour period that begins and ends with the analysis of the appropriate Continuing
             Calibration Check standards (CCC). Additional CCCs may be required depending on the
             length of the analysis batch and/or the number of Field Samples.

       3.3    INTERNAL STANDARD (IS) - A pure analyte added to an extract or standard solution
             in a known amount and used to measure the relative responses of other method analytes
             and surrogates.  The internal standard must be an analyte that is not a sample component.

       3.4    SURROGATE ANALYTE (SUR) - 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
             extraction or other processing, and is measured with the same procedures used to measure
             other sample components. The purpose of the SUR is to monitor method performance
             with each sample.

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3.5    LABORATORY REAGENT BLANK (LRB) - An aliquot of reagent water or other
      blank matrix that is treated exactly as a sample including exposure to all glassware,
      equipment, solvents, reagents, sample preservatives, internal standards, and surrogates
      that are used in the extraction batch. The LRB is analyzed is used to determine if method
      analytes or other interferences are present in the laboratory environment, the reagents, or
      the apparatus.

3.6    LABORATORY FORTIFIED BLANK (LFB) - An aliquot of reagent water or other
      blank matrix to which known quantities of the method analytes and all the preservation
      compounds are added. The LFB is analyzed exactly like a sample, and its purpose is to
      determine whether the methodology is in control, and whether the laboratory is capable of
      making accurate and precise measurements.

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

3.8    LABORATORY FORTIFIED SAMPLE MATRIX DUPLICATE (LFMD) - A second
      aliquot of the Field Sample used to prepare the LFM which is fortified, extracted and
      analyzed identically.  The LFMD is used instead of the Field Duplicate to access method
      precision and accuracy when the occurrence of target analytes is low.

3.9    LABORATORY DUPLICATES (LD1 and LD2) - Two aliquots of the same sample
      taken in the laboratory and analyzed separately with identical procedures.  Analyses of
      LD1 and LD2  indicate precision associated with laboratory procedures, but not with
      sample collection, preservation, and storage procedures.

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

3.11  STOCK STANDARD SOLUTION (SSS) - A concentrated solution containing one or
      more method analytes prepared  in the laboratory using assayed reference materials or
      purchased from a reputable commercial source.

3.12  PRIMARY DILUTION STANDARD SOLUTION (PDS) - A solution containing
      method analytes prepared in the laboratory from stock standard solutions and diluted as
      needed to prepare calibration solutions and other needed analyte solutions.
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       3.13   CALIBRATION STANDARD (CAL) - A solution prepared from the primary dilution
             standard solution or stock standard solutions and the internal standards and surrogate
             analytes. The CAL solutions are used to calibrate the instrument response with respect to
             analyte concentration.

       3.14   CONTINUING CALIBRATION CHECK (CCC) - A calibration standard containing one
             or more method analytes, which is analyzed periodically to verify the accuracy of the
             existing calibration for those analytes.

       3.15   QUALITY CONTROL SAMPLE (QC S) - A solution of method analytes of known
             concentrations that is obtained from a source external to the laboratory and different from
             the source of calibration standards. It is used to check standard integrity.

       3.16   METHOD DETECTION LIMIT (MDL) - The minimum concentration of an analyte that
             can be identified, measured and reported with 99% confidence that the analyte
             concentration is greater than zero (Section 9.2.4). This is a statistical determination of
             precision. Accurate quantitation is not expected at this level.(1)

       3.17   MINIMUM REPORTING LEVEL (MRL) - The minimum concentration that can be
             reported as a  quantitated value for a target analyte in a sample following analysis. This
             defined concentration can be no lower than the concentration of the lowest continuing
             calibration check standard for that analyte, and can only be used if acceptable quality
             control criteria for this standard are met.

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

4.      INTERFERENCES

       4.1    All glassware must be meticulously cleaned. Wash glassware with detergent and tap
             water, rinse with tap water, followed by reagent water. Non-volumetric glassware can be
             heated in a muffle furnace at 400 °C for 2 hours as a substitute for a solvent rinse.
             Volumetric glassware should not be heated in an oven above 120 °C.

       4.2    Method interferences may be caused by contaminants in solvents, reagents (including
             reagent water), sample bottles and caps, and other sample processing hardware that lead
             to discrete artifacts and/or elevated baselines in the chromatograms.  All items such as
             these must be routinely demonstrated to be free from interferences (less than V3 the MRL
             for each target analyte) under the conditions of the analysis by analyzing laboratory
             reagent blanks as described in Section 9.4.  Subtracting blank values from sample
             results is not permitted.

       4.3    Matrix interferences may be caused by contaminants that are co-extracted from the
             sample.  The  extent of matrix interferences will vary considerably from source to source,

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              depending upon the nature of the water.  Water samples high in total organic carbon may
              have elevated baseline or interfering peaks.

       4.4     Relatively large quantities of the buffer and preservatives (Sect. 8.1) are added to sample
              bottles. The potential for trace-level organic contaminants in these reagents exist.
              Interferences from these sources should be monitored by analysis of laboratory reagent
              blanks, particularly when new lots of reagents are acquired.

       4.5     Benzophenone was an interferent recovered at low level from one manufacturer's lot of
              tris(hydroxymethyl)aminomethane hydrochloride.  The spectra of benzophenone and 1,2-
              diphenylhydrazine are very similar, sharing the major m/z ions of 51, 77, 105, 152, and
              182. At first glance, the benzophenone may appear to be a contaminant in the LRB.
              Given that the two compounds share common ions, their chromatographic peaks must be
              resolved.

       4.6     During method development, one lot of anhydrous sodium sulfate was found to add an
              agent to the extract that, when injected, caused complete loss of prometon recovery and
              caused severe chromatographic tailing of the phenols. It is very important to check a new
              sodium sulfate lot before general use.  When only one or two samples with the interfering
              agent were injected, recovery of good chromatographic performance was possible by
              removing the first meter of the capillary column and replacing the deactivated glass inlet
              liner.

       4.7     Solid phase cartridges and disks and their associated extraction devices have been
              observed to be a source of interferences. The analysis of field and laboratory reagent
              blanks can provide important information regarding the presence or absence of such
              interferences. Brands and lots  of solid phase extraction devices should be tested to ensure
              that contamination will not preclude analyte identification and quantitation.

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

       4.9     Silicone compounds may be leached from punctured autosampler vial septa, particularly
              when particles of the septa sit in the vial.  These silicone compounds  should have no
              effect  on the analysis, but the analyst should be aware of this potential problem.
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
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             method. A reference file of MSDSs should be made available to all personnel involved in
             the chemical analysis. Additional references to laboratory safety are available.(2"4)

      5.2    Pure standard materials and stock standard solutions of these compounds should be
             handled with suitable protection to skin and eyes, and care should be taken not to breath
             the vapors or ingest the materials.

6.     EQUIPMENT AND SUPPLIES (All specifications are suggested.  Catalog numbers are
      included for illustration only.)

      6.1    SAMPLE CONTAINERS - 1 liter glass bottles fitted with polytetrafluoroethylene
             (PTFE) lined screw caps.

      6.2    VIALS - Various sizes of amber glass vials with PTFE lined screw caps for storing
             standard solutions and extracts.  Crimp-top glass autosampler vials, 2 mL, with PTFE
             faced septa.

      6.3    VOLUMETRIC FLASKS - Class A, suggested  sizes include 1, 5, and 10 mL, for
             preparation of standards and dilution of extract to final volume.

      6.4    GRADUATED CYLINDERS - Suggested sizes include 5, 10, and 250 mL.

      6.5    MICRO SYRINGES - Suggested sizes include 25, 50, 100, 250, 500, and 1000 mL.

      6.6    DRYING COLUMN - The drying column must be able to contain 5 to 7 g of anhydrous
             sodium sulfate.  The drying column should not leach interfering compounds or
             irreversibly adsorb target analytes. Any small column may be used, such as a glass pipet
             with glass wool plug.

      6.7    CONICAL CENTRIFUGE TUBES - 15 mL, or other glassware suitable for collection of
             the eluate from the cartridge or disk after extraction.

      6.8    COLLECTION TUBES OR VIALS - 25 mL or larger, or other glassware suitable for
             collecting extract from drying tube.  Conical centrifuge tubes, 50 mL, with graduations
             (VWR #: 21049-063) were used to develop this method.

      6.9    ANALYTICAL BALANCE - Capable of weighing to the nearest 0.0001 g.

      6.10   SOLID PHASE EXTRACTION (SPE) APPARATUS USING CARTRIDGES

             6.10.1  SOLID PHASE EXTRACTION CARTRIDGES - 6 mL, packed with 500 mg
                    (125 um dp) of polystyrene divinylbenzene (SDVB) sorbent phase (Varian Bond
                   Elut ENV phase; cat.#: 1225-5011 or equivalent).

             6.10.2  SAMPLE RESERVOIR AND TRANSFER TUBE- Sample reservoirs (VWR

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             cat.#: JT7120-3 or equivalent) with a volume of about 75 mL are attached to the
             cartridges to hold the water sample.  An alternative method is using transfer tubes
             (Supelco "Visiprep"; cat.#: 57275 or equivalent) which transfer the sample
             directly from the sample container to the SPE cartridge.

      6.10.3 VACUUM EXTRACTION MANIFOLD - With flow/vacuum control (Supelco
             cat.#: 57044 or equivalent). The use of replaceable needles or valve liners may be
             used to prevent cross contamination.

      6.10.4 REMOTE VACUUM GAUGE/BLEED VALVE ASSEMBLY - To monitor and
             adjust vacuum pressure delivered to the vacuum manifold (Supelco cat.#: 57161-
             U or equivalent)

      6.10.5 An automatic or robotic system, designed for use with SPE cartridges, may be
             used as long as all quality control requirements discussed in Section 9 are met.
             Automated systems may use either vacuum or positive pressure to process
             samples and solvents through the cartridge. All extraction and elution steps must
             be the same as in the manual procedure. Extraction or elution steps may not be
             changed or omitted to accommodate the use of an automated system.

6.11   SOLID PHASE EXTRACTION (SPE) APPARATUS USING DISKS

      6.11.1 SOLID PHASE EXTRACTION DISKS - 47 mm diameter and 0.5 mm thick,
             manufactured with a polystyrene divinylbenzene (SDVB) sorbent phase (Varian
             cat.  #: 1214-5010 or equivalent). Larger disks may be used as long as the QC
             performance  criteria outlined in Section 9 are met.

      6.11.2 SPE DISK EXTRACTION GLASSWARE - funnel,  PTFE coated  support screen,
             PTFE gasket, base, and clamp used to support SPE disks and contain samples
             during extraction. May be purchased as a set (Fisher cat. #:K971100-0047 or
             equivalent) or separately.

      6.11.3 VACUUM EXTRACTION MANIFOLD - Designed to accommodate extraction
             glassware and disks (Varian cat.#: 1214-6001 or equivalent).

      6.11.4 An automatic robotic system for disks as described in Section 6.10.5.

6.12   EXTRACT CONCENTRATION SYSTEM - Extracts are concentrated by blowdown
      with nitrogen using water bath set to 40°C (Meyer N-Evap, Model 111, Organomation
      Associates, Inc. or equivalent).

6.13   LABORATORY OR ASPIRATOR VACUUM SYSTEM - Sufficient capacity to
      maintain a vacuum of about 10 inches of mercury for cartridges. A greater vacuum of 15
      to 25  inches of mercury may be used with disks.
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6.14   GAS CHROMATOGRAPH/MASS SPECTROMETER (GC/MS)
       INSTRUMENTATION

       6.14.1 FUSED SILICA CAPILLARY GC COLUMN - 30 m x 0.25 mm i.d. fused silica
             capillary column coated with a 0.25 um bonded film of
             poly(dimethylsiloxy)poly(l,4-bis(dimethylsiloxy)phenylene)siloxane(J&WDB-
             5MS or equivalent).  Any capillary column that provides adequate resolution,
             capacity, accuracy, and precision as summarized in Section 17 may be used.  A
             nonpolar, low-bleed column is recommended for use with this method to provide
             adequate chromatography and minimize column bleed.

       6.14.2 GC INJECTOR AND OVEN - Capable of temperature programming and
             equipped for split/splitless injection. Target compounds included in this method
             are subject to thermal breakdown in the injector port, which increases when the
             injector is not properly deactivated or at excessive temperatures.  The injection
             system must not allow analytes to contact hot stainless steel or other metal
             surfaces that promote decomposition. The performance data in Section  17 was
             obtained by hot, splitless injection using a 4 mm i.d.  glass, deactivated liner
             (Restek cat.#: 20772).  Other injection techniques such  as temperature
             programmed injections, cold on-column injections and large volume injections
             may be used if the QC criteria in Sections 9 and 10 are met. Equipment designed
             appropriately for these alternate types of injections must be used if these options
             are selected.

       6.14.3 GC/MS INTERFACE - Interface should allow the capillary column or transfer
             line exit to be placed within a few mm of the ion source. Other interfaces, like jet
             separators, are acceptable as long as the system has adequate sensitivity  and QC
             performance criteria are met.

       6.14.4 MASS SPECTROMETER - The MS must be capable of electron ionization at a
             nominal electron energy of 70 eV to produce positive ions.  The spectrometer
             must be capable of scanning at a minimum from 45 to 450 amu with a complete
             scan cycle time (including scan overhead) of 1.0 second or less.  (Scan cycle time
             =  total MS data acquisition time in seconds divided  by number of scans in the
             chromatogram). The spectrometer must produce a mass spectrum that meets all
             criteria in Table 1 when a solution containing approximately 5 ng of DFTPP is
             injected into the GC/MS. Use a single spectrum at the apex of the DFTPP 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. The
             scan time should be set so that all analytes have a minimum of five scans across
             the chromatographic peak.  Seven to ten scans across chromatographic peaks are
             preferred.

       6.14.5 DATA SYSTEM - An interfaced data system is required to acquire, store, and
             output mass spectral data.  The computer software should have the capability of

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                    processing stored GC/MS data by recognizing a GC peak within a given retention
                    time window.  The software must allow integration of the ion abundance of any
                    specific ion between specified time or scan number limits. The software must be
                    able to calculate relative response factors, construct a linear regression or
                    quadratic calibration curve, and calculate analyte concentrations.

7.     REAGENTS AND STANDARDS

      7.1    REAGENTS AND SOLVENTS - Reagent grade or better chemicals should be used in all
             tests. Unless otherwise indicated, it is intended that all reagents will conform to the
             specifications of the Committee on Analytical Reagents of the American Chemical
             Society (ACS), where such specifications are available. Other grades may be used,
             provided it is first determined that the reagent is of sufficiently high purity to permit its
             use without lessening the quality of the determination.

             7.1.1   HELIUM - 99.999% or better, GC  carrier gas.

             7.1.2   REAGENT WATER - Purified water which does not contain any measurable
                    quantities of any target analytes or interfering compounds at or above 1/3 the
                    MRL for each compound of interest.

             7.1.3   METHANOL (CAS# 67-56-1) - High purity, demonstrated to be free of analytes
                    and interferences (B&J Brand GC2®, Capillary GC/GC-MS Grade or equivalent).

             7.1.4   ETHYL ACETATE (CAS# 141 -78-6) - High purity, demonstrated to be free of
                    analytes and interferences (B&J Brand GC2®, Capillary GC/GC-MS Grade or
                    equivalent).

             7.1.5   METHYLENE CHLORIDE (CAS# 75-09-02) - High purity, demonstrated to be
                    free  of analytes and interferences (B&J Brand GC2®, Capillary GC/GC-MS Grade
                    or equivalent).

             7.1.6   SODIUM SULFATE, ANHYDROUS (CAS# 7757-82-6) - Soxhlet extracted
                    with methylene chloride for a minimum of four hours or heated to 400°C for two
                    hours in a muffle furnace. One lot of "ACS grade" anhydrous sodium sulfate had
                    a contaminant that degraded the capillary column so that analyte recoveries were
                    unacceptable. An "ACS grade, suitable for pesticide residue analysis," or
                    equivalent, of anhydrous sodium sulfate is recommended.

             7.1.7   SAMPLE PRESERVATION  REAGENTS - These preservatives are solids at
                    room temperature and may be added to the sample bottle before shipment to the
                    field.

                    7.1.7.1 BUFFER SALT MIX, pH 7 - The sample must be buffered to pH 7 with
                          two components: 1) tris(hydroxymethyl)aminomethane, also called Tris,

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             0.47 g (CAS# 77-86-1, ACS Reagent Grade or equivalent); and 2)
             tris(hydroxymethyl)aminomethane hydrochloride, also called Tris HC1,
             7.28 g (CAS# 1185-53-1, ACS Reagent Grade or equivalent). Alternately,
             7.75 g of a commercial buffer crystal mixture, that is blended in proportion
             to the amounts given above, can be used.

       7.1.7.2 L-ASCORBIC ACID (CAS# 50-81-7) - Ascorbic acid reduces "free
             chlorine" at the time of sample collection (ACS Reagent Grade or
             equivalent).

       7.1.7.3 ETHYLENEDIAMINETETRAACETIC ACID, TRISODIUM SALT
             (Trisodium EDTA, CAS# 10378-22-0) - Trisodium EDTA is added to
             inhibit metal-catalyzed hydrolysis of analytes. The trisodium salt is used
             instead of the disodium salt because the trisodium salt solution pH is
             closer to the desired pH of 7 (Sigma cat.#: ED3SS or equivalent).

       7.1.7.4 DIAZOLIDINYL UREA (DZU) (CAS# 78491-02-8) - DZU is added to
             inhibit microbial growth. DZU (Sigma cat.#: D-5146) is commonly used
             as a preservative in cosmetics such as skin lotion.

STANDARD SOLUTIONS - When a compound purity is assayed to be 96% or greater,
the weight can be used without correction to calculate the concentration of the stock
standard. Solution concentrations listed in this section were used to develop this method
and are included as an example.  Standards for sample fortification generally should be
prepared in the smallest volume that can be accurately measured to minimize the addition
of excess organic solvent to aqueous samples.  Even though stability times for
standard solutions are suggested in the following sections, laboratories should used
standard QC practices to determine when their standards need to be replaced.

7.2.1   INTERNAL STANDARD SOLUTIONS - This method uses three internal
       standard compounds listed in the table below.
Internal Standards
acenaphthene-t/10
phenanthrene-6?10
chrysene-t/12
CAS#
15067-26-2
1517-22-2
1719-03-5
FW
164.3
188.3
240.4
       7.2.1.1 INTERNAL STANDARD PRIMARY DILUTION STANDARD (500
             ug/mL) - Prepare or purchase commercially the Internal Standard Primary
             Dilution Standard (PDS) at a concentration of 500 ug/mL. If prepared
             from neat or solid standards, this solution requires the preparation of a
             more concentrated stock standard similar to the procedure followed for the
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             analyte stock (Sect. 7.2.3.1).  The solvent for the Internal Standard PDS
             may be acetone or ethyl acetate. The Internal Standard PDS has been
             shown to be stable for 1 year in amber glass screw cap vials when stored at
             • 10°Corless.

       7.2.1.2 INTERNAL STANDARD EXTRACT FORTIFICATION SOLUTION (50
             ug/mL) - Dilute a portion of the Internal Standard PDS (500 ug/mL)
             (Sect. 7.2.1.1) to a concentration of 50 ug/mL in ethyl acetate and use this
             solution to fortify the final 1 mL extracts (Sect. 11.6). The Internal Extract
             Fortification Solution has been shown to be stable in amber glass screw
             cap vials for 6 months when stored at • 10°C or less.

       SURROGATE (SUR) ANALYTE STANDARD SOLUTIONS - The two
       surrogates for this method are listed in the table  below.
Surrogates
l,3-dimethyl-2-nitrobenzene
triphenylphosphate
CAS#
81-20-9
115-86-6
FW
151.2
326.3
7.2.3
7.2.2.1 SUR STOCK SOLUTION (~ 4 to 10 mg/mL) - Surrogate Stock Solutions
       may be purchased commercially or prepared from neat materials.  The
       solvent for the SUR Stock Solution may be acetone or ethyl acetate.
       These solutions have been shown to be stable for one year when stored in
       amber glass containers at -10°C or less.

7.2.2.2 SUR PRIMARY DILUTION STANDARD (SUR PDS) (500 ug/mL) -
       The 500 ug/mL SUR PDS may be purchased commercially or prepared by
       volumetric dilution of the SUR Stock Solutions (Sect. 7.2.2.1) in acetone
       or ethyl acetate The PDS has been shown to be stable for one year when
       stored in amber glass  screw cap vials at • 10°C  or less.  This solution is
       used to make the 50 ug/mL solution for sample fortification and also to
       prepare calibration solutions.

7.2.2.3 SUR SAMPLE FORTIFICATION SOLUTION (50 ug/mL) - Dilute the
       500 ug/mL SUR PDS in methanol to make a 50 ug/mL sample
       fortification solution.  Add 100 uL of this 50 ug/mL solution to each 1 liter
       water sample before extraction to give a concentration of 5 ug/L of each
       surrogate. This solution has been  shown to be  stable for six months when
       stored in amber glass  screw cap vials at • 10°C  or less.

ANALYTE STANDARD SOLUTIONS - Obtain the analytes listed in the table in
Section 1.1 as neat or solid standards or as commercially prepared ampulized
solutions from a reputable standard manufacturer. Prepare the Analyte Stock and
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      Primary Dilution Standards as described below.

      7.2.3.1 ANALYTE STOCK STANDARD SOLUTIONS (1 to 10 mg/mL) -
             Analyte standards may be purchased commercially as ampulized solutions
             or prepared from neat materials. Stock standards have been shown to be
             stable for one year when stored in amber glass screw cap vials at • 10°C or
             less.

      7.2.3.2 ANALYTE PRIMARY DILUTION STANDARDS (200 ug/mL and 20
             ug/mL) - Prepare the 200 ug/mL Analyte PDS by volumetric dilution of
             the Analyte Stock Standard Solution (Sect. 7.2.3.1) in ethyl acetate to
             make a 200 ug/mL solution. The 20 ug/mL Analyte PDS can be made by a
             volumetric dilution of the 200 ug/mL Analyte PDS in ethyl acetate. The
             Analyte PDSs are used to prepare calibration and fortification standards.
             They have been shown to be stable for six months when stored in an
             amber glass screw cap vial at • 10°C or less. Check frequently for signs
             of evaporation, especially before preparing calibration solutions.

7.2.4  CALIBRATION SOLUTIONS - Prepare a calibration curve of at least 5 CAL
      levels over the concentration range of interest from dilutions of the Analyte PDSs
      in ethyl acetate. All calibration solutions should contain at least 80% ethyl acetate
      so that gas chromatographic performance is not compromised. The lowest
      concentration of calibration standard must be at or below the MRL. The level of
      the MRL will depend on system sensitivity.  A constant concentration of each
      internal standard and surrogate (in the range of 2 to 5 ng/uL) is added to each
      CAL. For instance, for method development work, 50 uL of the 500 ug/mL
      Internal Standard PDS and 50 uL of the 500 ug/mL SUR PDS were added to each
      CAL level standard for final concentrations of 5 ug/mL.  The calibration solutions
      have been shown to be stable for six months when stored in an amber glass screw
      cap vial at • 10°C or less.

7.2.5  ANALYTE FORTIFICATION SOLUTIONS (0.05 to 5.0 ug/mL) - The Analyte
      Fortification Solutions contain all method analytes of interest in methanol. They
      are prepared by dilution of the Analyte PDSs (200 ug/mL or 20  ug/mL).  These
      solutions are used to fortify the LFBs, the LFMs and LFMDs with method
      analytes. It is recommended that three concentrations be prepared so that the
      fortification levels can be rotated. The Analyte Fortification Solutions have been
      shown to be stable for six months when stored in an amber glass screw cap vial at
      • 10°C or less.

7.2.6  GC/MS TUNE CHECK SOLUTION (5 ug/mL) - Prepare a
      Decafluorotriphenylphosphine (DFTPP) solution in methylene chloride.  DFTPP
      is more stable in methylene chloride than in acetone or ethyl acetate.  Store this
      solution in an amber glass screw cap vial at • 10°C or less.
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8.
SAMPLE COLLECTION. PRESERVATION. AND STORAGE
       8.1     SAMPLE BOTTLE PREPARATION

              8.1.1  Grab samples must be collected in accordance with conventional sampling
                    practices(5) using a 1 liter or 1 quart amber or clear glass bottle fitted with PTFE-
                    lined screw-caps.

              8.1.2  Preservation reagents, listed in the table below, are added to each sample bottle
                    prior to shipment to the field.
Compound
L- Ascorbic Acid
Ethylenediaminetetraacetic acid
trisodium salt
Diazolidinyl Urea
*Tris(hydroxymethyl)aminomethane
*Tris(hydroxymethyl)aminomethane
hydrochloride
Amount
O.lOg/L
0.35 g/L
1.0 g/L
0.47 g/L
7.28 g/L
Purpose
Dechlorination
Inhibit metal -catalyzed
hydrolysis of targets
Microbial inhibitor
First component of pH 7
buffer mixture
Second component of pH
7 buffer mixture
                     * Alternately, 7.75 g of a commercial buffer crystal mixture, that is blended in the
                     proportions given in the table, can be used (Sect. 7.1.7.1).

                     8.1.2.1 Residual chlorine must be reduced at the time of sample collection with
                           100 mg of ascorbic acid per liter.  Sodium thiosulfate and sodium sulfite
                           cannot be used because they were found to degrade target analytes. In
                           addition, while ammonium  chloride is effective in converting free chlorine
                           to chloramines, the chloramines also caused target compound loss.

                     8.1.2.2 Ethylenediaminetetraacetic  acid, trisodium salt (trisodium EDTA) (0.35 g)
                           must be added to inhibit metal-catalyzed hydrolysis of the target analytes,
                           principally terbufos, disulfoton, diazinon, fonofos, and cyanazine.

                     8.1.2.3 Diazolidinyl urea (1.0 g) is  added to inhibit microbial degradation of
                           analytes.  Diazolidinyl urea is used in cosmetics such as skin lotion. The
                           antimicrobial activity of diazolidinyl urea has been proposed as due to
                           protein alkylation of sulfhydryl groups and the ability to release
                           formaldehyde.(6)  Plate count studies conducted during method
                           development indicated that  it was effective in inhibiting microbial
                           degradation for extended periods.

                     8.1.2.4 The sample  must be buffered to pH 7 to reduce the acid and base catalyzed
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                           hydrolysis of target analytes.  The pH buffer has two components:
                           tris(hydroxymethyl)aminomethane (0.47 g) and
                           tris(hydroxymethyl)aminomethane hydrochloride (7.28 g). A
                           commercially prepared combination of these two compounds can be
                           purchased as pre-mixed crystals. When using the pH 7 pre-mixed crystals,
                           add 7.75 g per liter of water sample.

       8.2    SAMPLE COLLECTION

             8.2.1   When sampling from a cold water tap, remove the aerator so that no air bubbles
                    will be trapped in the sample.  Open the tap and allow the system to flush until the
                    water temperature has stabilized (usually about 3-5 minutes).  Collect samples
                    from the flowing system.

             8.2.2   When sampling from an open body of water, fill a 1 quart wide-mouth bottle or 1
                    L beaker with water sampled from  a representative area, and carefully fill sample
                    bottles from the container. Sampling equipment,  including automatic samplers,
                    must be free of plastic tubing, gaskets, and other parts that may leach interfering
                    analytes into the water sample.

             8.2.3   Fill sample bottles, taking care not to flush out the sample preservation reagents.
                    Samples do not need to be collected headspace free.

             8.2.4   After collecting the sample, cap the bottle and agitate by hand until preservatives
                    are dissolved. Keep the sample sealed from time of collection until extraction.

       8.3    SAMPLE SHIPMENT AND STORAGE - Samples must be chilled during shipment and
             must not exceed 10°C during the first 48 hours after collection. Samples should be
             confirmed to be at or below 10°C when they are received at the laboratory. Samples
             stored in the lab must be held at or below 6°C until extraction, but should not be frozen.

       8.4    SAMPLE AND EXTRACT HOLDING TIMES - Results of the sample storage stability
             study (Sect. 17, Table 7) indicated that most compounds  listed in this method have
             adequate stability for 14 days when collected, dechlorinated, preserved, shipped and
             stored as described in Sections 8.1, 8.2, and 8.3. At 14 days, even the most unstable
             compound, terbufos, was recovered above 60 %.  Water samples should be extracted as
             soon as possible, but must be extracted within 14 days. The extract storage stability study
             must be stored at 0°C or less and analyzed within 28 days after extraction.  The extract
             storage stability study data are presented in Section 17, Table 8.

9.      QUALITY CONTROL

       9.1    Quality control (QC) requirements include the Initial Demonstration of Capability (Sect.
             17, Table 9), the determination of the MDL, and subsequent analysis in each analysis
             batch of a Laboratory Reagent Blank (LRB), Continuing  Calibration Check Standards

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       (CCC), a Laboratory Fortified Blank (LFB), a Laboratory Fortified Sample Matrix
       (LFM), and either a Laboratory Fortified Sample Matrix Duplicate (LFMD) or a Field
       Duplicate Sample. This section details the specific requirements for each QC parameter.
       The QC criteria discussed in the following sections are summarized in Section 17, Tables
       9 and 10. These criteria are considered the minimum acceptable QC criteria, and
       laboratories are encouraged to institute additional QC practices to meet their specific
       needs.

9.2    INITIAL DEMONSTRATION OF CAPABILITY (IDC) - Requirements for the Initial
       Demonstration of Capability are described in the following sections and summarized in
       Section 17, Table 9.

       9.2.1  INITIAL DEMONSTRATION OF LOW SYSTEM BACKGROUND - Any time
             a new lot of solid phase extraction (SPE) cartridges or disks is used, it must be
             demonstrated that a laboratory reagent blank (Sect. 9.4) is reasonably free  of
             contamination and that the criteria in Section 9.4 are met.

       9.2.2  INITIAL DEMONSTRATION OF PRECISION - Prepare, extract, and analyze 4-
             7 replicate LFBs fortified near the midrange of the initial calibration curve
             according to the procedure described in Section 11. Sample preservatives as
             described in Section 8.1 must be added to these samples. The relative standard
             deviation (RSD) of the results of the replicate analyses must be less than 20%.

       9.2.3  INITIAL DEMONSTRATION OF ACCURACY - Using the same set of replicate
             data generated for Section 9.2.2, calculate average recovery.  The average
             recovery of the replicate values must be within ±30% of the true value.

       9.2.4  MDL DETERMINATION - Prepare, extract and analyze at least seven replicate
             LFBs at a concentration estimated to be near the MDL, over a period of at least
             three days (both extraction and analysis should be conducted over at least three
             days) using the procedure described in Section 11. The fortification level  may be
             estimated by selecting a concentration with  a signal of 2 to 5 times the noise level.
             The appropriate concentration will be dependent upon the sensitivity of the
             GC/MS system being used.  Sample preservatives as described in Section  8.1
             must be added to these samples.  Calculate the MDL using the equation

                    MDL = St(n. 1; j . ajpj,., = 0 99)

                    where
                    V -1, i - alpha = 0.99) = Students t value for the 99% confidence level with n-1
                    degrees of freedom,
                    n = number of replicates, and
                    S = standard deviation of replicate analyses.

             NOTE: Do not subtract blank values when performing MDL calculations.  The

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             MDL is a statistical determination of precision only.(1) If the MDL replicates are
             fortified at a low enough concentration, it is likely that they will not meet
             precision and accuracy criteria.

       9.2.5  METHOD MODIFICATIONS - The analyst is permitted to modify GC columns,
             GC conditions, evaporation techniques, internal standards or surrogate standards,
             but each time such method modifications are made, the analyst must repeat the
             procedures of the IDC (Sect. 9.2).

9.3     MINIMUM REPORTING LEVEL (MRL) - The MRL is a threshold concentration of an
       analyte that a laboratory can expect to accurately quantitate in an unknown sample. The
       MRL should be established at an analyte concentration that is either greater than three
       times the MDL or at an analyte concentration which would yield a response greater than a
       signal-to-noise ratio of five. Although the lowest calibration standard for an analyte
       may be below the MRL, the MRL must never be established at a concentration
       lower than the lowest calibration standard.

9.4     LABORATORY REAGENT BLANK (LRB) - An LRB is required with each extraction
       batch (Sect. 3.1) of samples to determine the background system contamination. If the
       LRB produces a peak within the retention time window of any analyte that would prevent
       the determination of that analyte, determine the source of contamination and eliminate the
       interference before processing samples.  Background contamination must be reduced to
       an acceptable level before proceeding. Background from method analytes or
       contaminants that interfere with the measurement of method analytes must be below 1/3
       of the MRL. If the target 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 in the extraction batch.

9.5     CONTINUING CALIBRATION CHECK (CCC) - A CCC is a standard prepared with all
       compounds of interest which is analyzed during the analysis batch to ensure the stability
       of the instrument initial calibration. This calibration check is required at the beginning of
       each day that samples are analyzed, after every ten injections, and at the end of any group
       of sample analyses.  See Section 10.3 for concentration requirements and acceptance
       criteria.

9.6     LABORATORY FORTIFIED BLANK (LFB) - An LFB is required with each extraction
       batch (Sect. 3.6). The fortified concentration of the LFB should be rotated between low,
       medium, and high concentrations from day to day. The low concentration LFB  must be
       as near as practical to, but no more than two times the MRL. Similarly, the high
       concentration LFB should be near  the high end of the calibration range established during
       the initial calibration (Sect. 10.2).  Results of the low-level LFB analyses must be 50-
       160% of the true value.  Results of the medium and high-level LFB analyses must be 70-
       130% of the true value.  If the LFB results do not meet these criteria for target analytes,
       then all data for the problem analyte(s) must be considered invalid for all samples in the
       extraction batch.

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9.7    MS TUNE CHECK - A complete description of the MS tune check is in Section 10.2.1.
       This check must be performed each time a major change is made to the mass
       spectrometer, and prior to establishing and/or re-establishing an initial calibration (Sect.
       10.2). In this method daily DFTPP analysis is not required.

9.8    INTERNAL STANDARDS (IS) - The analyst must monitor the peak area of each
       internal standard in all injections during each analysis day. The IS response (as indicated
       by peak area) for any chromatographic run must not deviate by more than ±50% from the
       average area measured during the  initial calibration for that IS. A poor injection could
       cause the IS area to exceed these criteria.  Inject a second aliquot of the suspect extract to
       determine whether the failure is due to poor injection or instrument response drift.

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

       9.8.2   If the internal standard area for the reinjected extract deviates greater than  50%
              from the initial calibration average, the analyst should check the continuing
              calibration check standards that ran before and after the sample.  If the continuing
              calibration check fails the criteria of Section 9.5 and 10.3, recalibration is in order
              per Section 10.  If the calibration standard is acceptable, extraction of the sample
              should be repeated provided the sample is still within holding time.  Otherwise,
              report results obtained from the reinjected extract,  but annotate as suspect.

9.9    SURROGATE RECOVERY - The surrogate standards are fortified into the aqueous
       portion of all  samples, duplicates,  LRBs, LFMs and LFMDs prior to extraction.
       Surrogates are also added to the calibration curve and calibration check standards. The
       surrogate is a means of assessing method performance from extraction to final
       chromatographic measurement.

       9.9.1   When surrogate recovery from a sample, blank, or CCC is less than 70% or
              greater than 130%, check (1) calculations to locate possible errors, (2) standard
              solutions for degradation, (3) contamination, and (4) instrument performance. If
              those steps do not reveal the cause of the problem, reanalyze the extract.

       9.9.2   If the extract reanalysis meets the surrogate  recovery criterion, report only  data for
              the reanalyzed extract.

       9.9.3   If the extract reanalysis fails the 70-130% surrogate recovery criterion, the analyst
              should check the surrogate calibration by analyzing the most recently acceptable
              calibration standard. If the calibration standard fails the 70-130% surrogate
              recovery criteria of Section 9.9.1, recalibration is in order.  If the surrogate
              recovery of the calibration standard is acceptable, extraction of the sample should
              be repeated, provided the sample is still within the holding time. If the sample re-
              extract also fails the recovery criterion, report all data for that sample as
              suspect/surrogate recovery.

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       9.9.4   The surrogate, l,3-dimethyl-2-nitrobenzene, is used to track the recovery of
              nitrobenzene. The other surrogate, triphenylphosphate, monitors the recovery of
              all the other target analytes.  If nitrobenzene is not included on the target analyte
              list, then the first surrogate, l,3-dimethyl-2-nitrobenzene, does not need to be
              analyzed.

9.10   LABORATORY FORTIFIED SAMPLE MATRIX AND DUPLICATE (LFM AND
       LFMD) - Analyses of LFMs (Sect. 3.7) are required in each extraction batch and are used
       to determine that the sample matrix does not adversely affect method accuracy. If the
       occurrence of target analytes in the samples is infrequent, or if historical trends are
       unavailable, a second LFM, or LMFD, must be prepared, extracted, and analyzed from a
       duplicate field sample used to prepare the LFM to assess method precision. Extraction
       batches that contain LFMDs will not require the analysis of a Field Duplicate (Sect. 9.11).
       If a variety of different sample matrices are analyzed regularly, for example, drinking
       water from groundwater and surface water sources, method performance should be
       established for each. Over time, LFM data should be documented for all routine sample
       sources for the laboratory.

       9.10.1  Within each extraction batch, a minimum of one field sample is fortified as an
              LFM for every 20 samples extracted. The LFM is prepared by spiking a sample
              with an appropriate amount of Analyte PDS (Sect. 7.2.5).  Select a  spiking
              concentration that is at least twice the matrix background concentration, if known.
              Use historical data or rotate through the designated concentrations to select a
              fortifying concentration. Selecting a duplicate bottle of a sample that has already
              been analyzed aids in the selection of appropriate spiking levels.

       9.10.2  Calculate the percent recovery (R) for each analyte using the equation

                                       (A-B)
                                  R=           *100

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

       9.10.3  Analyte recoveries may exhibit matrix bias. For samples fortified at or above
              their native concentration, recoveries should range between 70 and 130%, except
              for low-level fortification near or at the MRL where 50 to 160% recoveries are
              acceptable. If the accuracy of any analyte falls outside the designated range, and
              the laboratory performance for that analyte is shown to be in control in the LFB,
              the recovery is judged to be matrix biased. The result for that analyte in the
              unfortified sample is labeled suspect/matrix to inform the data user that the results
              are suspect due to matrix effects.
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       9.10.4 If an LFMD is analyzed instead of a Field Duplicate (Sect. 9.11), calculate the
                             D „ _     LFM- LFMD    , AA
                             RPD = 	* 100
                                    (LFM+ LFMD)/2
             relative percent difference (RPD) for duplicate LFMs (LFM and LFMD) using the
             equation RPDs for duplicate LFMs should fall in the range of ±30% for samples
             fortified at or above their native concentration. Greater variability may be
             observed when LFMs are spiked near the MRL. At the MRL, RPDs should fall in
             the range of ±50% for samples fortified at or above their native concentration. If
             the accuracy of any analyte falls outside the designated range, and the laboratory
             performance for that analyte is shown to be in control in the LFB, the recovery is
             judged to be matrix biased.  The result for that analyte in the unfortified sample is
             labeled suspect/matrix to inform the data user that the results are suspect due to
             matrix effects.
9.11   FIELD DUPLICATES (FD1 AND FD2) - Within each extraction batch, a minimum of
       one Field Duplicate (FD) or LFMD (Sect. 9.10) must be analyzed.  FDs check the
       precision associated with sample collection, preservation, storage, and laboratory
       procedures. If target analytes are not routinely observed in field samples, a LFMD (Sect.
       9.10) should be analyzed to substitute for this requirement. Extraction batches that
       contain LFMDs (Section 9.10) will not require the analysis of a Field Duplicate.

       9.11.1 Calculate the relative percent difference (RPD) for duplicate measurements (FD1
             and FD2) using the equation

                                  Dnrk    FD1-FD2     1AA
                                 RPD = 	*  100    tr\
                                         (FDl + FD2)/2          l'
       9.11.2 RPDs for duplicates should be in the range of ±30%. Greater variability may be
             observed when analyte concentrations are near the MRL. At the MRL, RPDs
             should fall in the range of ±50%. If the accuracy of any analyte falls outside the
             designated range, and the laboratory performance for that analyte is shown to be
             in control in the LFB, the recovery is judged to be matrix biased. The result for
             that analyte in the unfortified sample is labeled suspect/matrix to inform the data
             user that the results are suspect due to matrix effects.

9.12   QUALITY CONTROL SAMPLES (QCS) - Each time that new standards are prepared or
       a new calibration curve is run, analyze a QCS from a source different than the source of
       the calibration standards. The QCS may be injected as a calibration standard or fortified
       into reagent water and analyzed as a LFB. If the QCS is analyzed as a continuing

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             calibration, then the acceptance criteria are the same as for the CCC. If the QCS is
             analyzed as a LFB, then the acceptance criteria are the same as for an LFB. If measured
             analyte concentrations are not of acceptable accuracy, check the entire analytical
             procedure to locate and correct the problem source.

10.     CALIBRATION AND STANDARDIZATION

       10.1   Demonstration and documentation of acceptable mass spectrometer tune and initial
             calibration is required before any samples are analyzed. After the initial calibration is
             successful, a continuing calibration check is required at the beginning and end of each
             period in which analyses are performed, and after every tenth sample. Verification of
             mass spectrometer tune must be repeated each time a major instrument modification is
             made or maintenance is performed, and prior to analyte calibration.

       10.2   INITIAL CALIBRATION

             10.2.1  MS TUNE/MS TUNE CHECK- Calibrate the mass and abundance scales of the
                    MS with calibration compounds and procedures prescribed by the manufacturer
                    with any modifications necessary to meet tuning requirements.  Inject 5 ng or less
                    of the DFTPP solution (Sect.  7.2.6) into the GC/MS system. Acquire a mass
                    spectrum that includes data for m/z 45-450. Use a single spectrum at the apex of
                    the DFTPP 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.  If the DFTPP mass spectrum does not meet all criteria in Table 1, the MS
                    must be retuned and adjusted to meet all  criteria before proceeding with the initial
                    calibration.

             10.2.2 INSTRUMENT CONDITIONS - Operating conditions are described below.
                    Conditions different from those described may be used if QC criteria in Section 9
                    are met. Different conditions include alternate GC columns, temperature
                    programs,  and injection techniques, such as cold on-column and large volume
                    injections. Equipment designed for alternate types of injections must be used if
                    these options are selected.

                    10.2.2.1 Inject 1 uL into a hot, splitless injection port held at 210°C with a split
                            delay of 1 min. The temperature program is as follows: initially hold at
                            55°C for one minute, then ramp at 8°C/ min to 320°C.  Total run time is
                            approximately 33  min.  Begin data acquisition at 3.5 minutes.

                          Note: The GC was operated in a constant flow rate mode at a rate of 1.4
                          mL per minute and an initial head-pressure of 12.2 psi.

                    10.2.2.2 Many of the target compounds exhibit decreased sensitivity for low-level
                            injections due to degradation or irreversible adsorption in the injector
                            port. Deactivated glass or quartz inlet liners are recommended.

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       10.2.2.3 MS Detection and Sensitivity - Acquire and store data from m/z 45 to
               450 with a total cycle time (including scan overhead time) of 1.0 second
               or less.  Adjust the cycle time to measure at least five or more spectra
               during the elution of each GC peak.  Seven to ten scans across each GC
               peak are recommended. The GC/MS/DS peak identification software
               must be able to recognize a GC peak in the appropriate retention time
               window for each of the compounds in the calibration solution, and make
               correct qualitative identifications.

10.2.3  CALIBRATION SOLUTIONS -  Prepare a set of at least 5 calibration standards
       as described in Section 7.2.4. The lowest concentration of the calibration standard
       must be at or below the MRL, which will  depend on system sensitivity.
       Acceptable calibration over a large dynamic range, greater than about 50 fold
       range, may require multiple calibration curves.

10.2.4  CALIBRATION - The system is calibrated using the internal  standard technique.
       Concentrations may be calculated through the use of average relative response
       factor (RRF) or through the use of a calibration curve.  Calculate the RRFs using
       the equation
                 RRF =
      where: Ax =          integrated abundance (peak area) of the quantitation ion of
                           the analyte,
             A;s =          integrated abundance (peak area) of the quantitation ion
                           internal standard,
             Qx =          quantity of analyte injected in ng or concentration units,
                           and
             Qis =          quantity of internal standard injected in ng or concentration
                           units.

      Average RRF calibrations may only be used if the RRF values over the calibration
      range are relatively constant (<30% RSD). Average RRF is determined by
      calculating the mean RRF of a minimum of five calibration concentrations.

10.2.5 As an alternative to calculating average RRFs and applying the RSD test, use the
      GC/MS data system software to generate a linear regression or quadratic
      calibration curve.  The analyst may choose whether or not to force zero to obtain a
      curve that best fits the data.  Examples of common GC/MS system calibration
      curve options are:  1) Ax /Ais vs Qx /Qis and 2) RRF vs Ax /Ajs.

10.2.6 Acceptance criteria for the calibration of each analyte is determined by calculating
      the concentration of each analyte and surrogate in each of the analyses used to
      generate the calibration curve or average RRF. Each calibration point, except the

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             lowest point, for each analyte must calculate to be 70-130 % of its true value.  The
             lowest point must calculate to be 50-150% of its true value.  If this criteria cannot
             be met, reanalyze the calibration standards, restrict the range of calibration, or
             select an alternate method of calibration. The data presented in this method were
             obtained using quadratic fit (RRF vs. amount).  Quadratic fit calibrations should
             be used with caution, because the non-linear area of the curve may not be
             reproducible.

10.3    CONTINUING CALIBRATION CHECK (CCC) - The CCC verifies the initial
       calibration at the beginning and end of each group of analyses, and after every 10th
       sample during analyses. In this context, a "sample" is considered to be a field sample.
       LRBs, LFBs, LFMs, LFMDs and CCCs are not counted as samples. The beginning CCC
       for each analysis batch must be at or below the MRL in order to verify instrument
       sensitivity prior to any  analyses.  If standards have been prepared such that all low CAL
       points are not in the same CAL solution, it may be necessary to analyze two CAL
       solutions to meet this requirement.  Subsequent CCCs should alternate between a
       medium and high concentration.

       10.3.1 Inject an aliquot of the appropriate concentration calibration solution and analyze
             with the same conditions  used during the initial  calibration.

       10.3.2 Determine that  the absolute areas of the quantitation ions of the internal  standards
             have not changed by more than ± 50% from the areas measured during initial
             calibration.  If any IS area has changed by more this amount, remedial action must
             be taken  (Sect.  10.3.4). Control charts are useful aids in documenting system
             sensitivity changes.

       10.3.3 Calculate the concentration of each analyte and  surrogate in the check standard.
             The calculated amount for each analyte for medium and high level CCCs must be
             ±30% of the true value. The calculated amount for the lowest calibration level for
             each analyte must be within ±50% of the true value. If these conditions  do not
             exist, then all data for the problem analyte must be considered invalid, and
             remedial action (Sect. 10.3.4) should be taken which may require recalibration.
             Any field sample extracts that have been analyzed since the last acceptable
             calibration verification should be reanalyzed after adequate calibration has been
             restored, with the following exception.  If the continuing calibration fails because
             the calculated concentration is greater than  130% (150% for the low-level  CCC)
             for a particular target compound, and field sample extracts show no detection for
             that target compound, non-detects  may be reported without re-analysis.

       10.3.4 REMEDIAL ACTION -  Failure to meet CCC QC performance criteria may
             require remedial action. Major maintenance such as cleaning an ion source,
             cleaning  quadrapole rods, replacing filament assemblies, etc., require returning to
             the initial calibration step (Sect. 10.2).
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11.     PROCEDURE

       11.1   Important aspects of this analytical procedure include proper preparation of laboratory
             glassware and sample containers (Sect. 4.1), and sample collection and storage (Sect. 8).
             This section describes the procedures for sample preparation, solid phase extraction
             (SPE) using cartridges or disks, and extract analysis.

       11.2   SAMPLE BOTTLE PREPARATION

             11.2.1 Samples are preserved, collected and stored as presented in Section 8.  All field
                    and QC samples must contain the preservatives listed in Section 8.1.2, including
                    the LRB and LFB. Before extraction, mark the level of the sample on the outside
                    of the sample bottle for later sample volume determination. If using weight to
                    determine volume (Sect. 11.3.7), weigh the bottle with collected sample before
                    extraction.

             11.2.2 Add an aliquot of the surrogate fortification solution to each sample to be
                    extracted.  For method development work, a 100 uL aliquot of the 50 ug/mL SUR
                    Sample Fortification Solution (Sect. 7.2.2.3) was added to 1 L for a final
                    concentration of 5.0 ug/L.

             11.2.3 If the sample is an LFB, LFM, or LFMD, add the necessary amount of analyte
                    fortification solution.  Swirl each sample to ensure all components are mixed.

             11.2.4 Proceed with sample extraction using either SPE cartridges (Sect. 11.3) or disks
                    (Sect. 11.4).

       11.3   CARTRIDGE SPE PROCEDURE - The cartridge extraction procedure is carried out in a
             manual mode or by using a robotic or automatic sample preparation device. This section
             describes a SPE manual procedure using the equipment outlined in Section 6.10. The
             manual mode of sample addition to cartridges is performed with a large reservoir attached
             to the cartridge or with a transfer tube from the sample bottle to the cartridge.  Cartridge
             extraction data in Section 17 was collected using the transfer tube option described
             below.

             11.3.1 CARTRIDGE CLEANUP - Attach the extraction cartridges to the vacuum
                    manifold.  Rinse each  cartridge with a 5-mL aliquot of ethyl acetate, allowing the
                    sorbent to soak in the ethyl acetate for about 1 minute by turning off the vacuum
                    temporarily. Repeat with a 5-mL aliquot of methylene chloride (MeCl2). Let the
                    cartridge vacuum dry after each flush.

             11.3.2 CARTRIDGE CONDITIONING - This conditioning step is critical for recovery
                    of analytes and can have a marked effect on method precision and accuracy. If the
                    cartridge goes dry during the  conditioning  phase, the conditioning must be started
                    over. Once the conditioning has begun, the cartridge must not go dry until the last

                                            526-24

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      portion of the sample passes because analyte and surrogate recoveries may be
      affected. The analyst should note premature drying of the solid phase, because the
      sample may require re-extraction due to low surrogate recoveries.

      11.3.2.1  CONDITIONING WITH METHANOL - Rinse each cartridge with a 5-
               mL aliquot of methanol (MeOH), allowing the sorbent to soak for about
               30 seconds by turning off the vacuum temporarily.  From this point on,
               do not allow the cartridge to go dry until after extraction is complete.
               Drain most of the MeOH without going below the top of the cartridge
               packing and rinse again with a 5-mL aliquot of MeOH.

      11.3.2.2  CONDITIONING WITH REAGENT WATER - Drain most of the
               MeOH and rinse the cartridge with two consecutive 5-mL aliquots of
               reagent water, being careful not to allow the water level to go below the
               cartridge packing.  Turn off the vacuum. Fill the cartridge to the top
               with reagent water and attach a reservoir or a transfer tube (Sect. 6.10.2).

11.3.3 CARTRIDGE EXTRACTION - Prepare samples, including the QC samples, as
      specified in Section 11.2. The sample may be added to the cartridge using either a
      large reservoir attached to the cartridge or using a transfer tube from the sample
      bottle to the cartridge.

      11.3.3.1  SAMPLE ADDITION USING RESERVOIRS  - Attach a reservoir to
               the conditioned cartridge from Section 11.3.2.  Fill the reservoir with
               sample and turn on the vacuum adding additional aliquots of sample
               until the entire  1 L sample is processed. Adjust the vacuum so that the
               flow rate is about 20 mL/min. Do not let the cartridge packing go dry
               before all the sample has been extracted. After all of the sample has
               passed through the SPE cartridge, draw air through the cartridge for 10
               minutes at full vacuum (minus 10 to 15 inches Hg). If the cartridge is
               dried for period much longer than  10 minutes, there may be a loss of
               recovery for nitrobenzene and the surrogate  l,3-dimethyl-2-
               nitrobenzene.  After drying, turn off and release vacuum.

      11.3.3.2  SAMPLE ADDITION USING TRANSFER TUBES - Fit the PTFE
               transfer tube adapter securely to the conditioned cartridge. The screw on
               the adapter must be finger-tight, otherwise, air can leak and the cartridge
               may go dry. Place the weighted end of the transfer tube inside on the
               bottom of the sample bottle. Adjust the  flow rate to about 20 mL/min.
               If the adapter is securely attached, the water level in the cartridge should
               drop only as much as the volume of the transfer tube and no more. Do
               not let the  SPE sorbent go dry before all the sample has been extracted.
               After all the sample has passed through the SPE cartridge, draw air
               through the cartridge for 10 minutes at full vacuum (minus 10 to 15
               inches Hg). If the cartridge is dried for a much longer period than  10

                              526-25

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               minutes, there may be a loss of recovery for nitrobenzene and the
               surrogate l,3-dimethyl-2-nitrobenzene. After drying, turn off and
               release vacuum.

11.3.4 CARTRIDGE ELUTION - Keep reservoirs or transfer tubes attached.  Lift the
      manifold top, place collection tubes into the extraction tank, and insert valve
      liners into the collection tubes for extract collection.  Add 5 mL of ethyl acetate
      (EtAc) to the empty sample bottle and rotate the bottle on its side, rinsing the
      inside of the bottle.  If using the cartridge reservoir method, pour the EtAc from
      the bottle into the cartridge reservoir and draw enough of the EtAc through the
      cartridge to soak the sorbent. If using the transfer tubes method, pull the EtAc
      through the PTFE transfer tubes and draw enough of the EtAc through the tubes
      into the cartridge to soak the sorbent. Turn off the vacuum and vent the system
      and allow the sorbent to soak in EtAc for approximately 30 seconds. Start a low
      vacuum (minus 2-4 in Hg) and pull the ethyl acetate through in a dropwise fashion
      into the collection tube.  Repeat rinse with  5 mL MeCl2. Take off reservoirs and
      transfer tubes and rinse the cartridge body with 2 to 3 mLs of 1:1 mixture of
      MeCl2 and EtAc (1:1 MeCl2/EtAc).

11.3.5 DRYING OF THE EXTRACT - Small amounts of residual water from the
      sample container and solid phase may form an immiscible layer with the solvent
      in the extract.  Set up a  drying column (Sect. 6.6) packed with about 5 grams of
      anhydrous sodium sulfate. Pre-rinse the sodium sulfate column with about 2 mL
      of 1:1 EtAc/MeCl2.  Place a clean collection tube that can hold at least 20 mL
      beneath the drying column.  Add the extract to the column and follow with two, 3
      mL aliquots of 1:1 EtAc/MeCl2.

11.3.6 EXTRACT CONCENTRATION - Concentrate the extract to about 0.7 mL under
      a gentle stream of nitrogen in a warm water bath (at ~ 40°C). Do not blow down
      samples to less than 0.5 mL, because the most volatile compounds will show
      diminished recovery. Transfer the extract to a 1  mL volumetric flask and add the
      internal standard (method development used 100 uL of 50 ug/mL internal standard
      solution for an extract concentration of 5 ug/mL). Rinse the collection tube that
      held the dried extract with small amounts of EtAc and add to the volumetric flask
      to bring the volume up to the 1 mL mark. Transfer to autosampler vial.

11.3.7 SAMPLE VOLUME OR WEIGHT DETERMINATION - Use a graduated
      cylinder to measure the volume of water required to fill the original sample bottle
      to the mark made prior to extraction (Sect.  11.2.1). Determine volume to the
      nearest 10 mL for use in the final calculations of analyte concentration (Sect.
      12.2).  If using weight to determine volume, reweigh empty sample bottle. From
      the weight of the original sample bottle measured in Section 11.2.1, subtract the
      empty bottle weight.  Use this value for analyte concentration calculations in
      Section 12.2.
                              526-26

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11.4  DISK SPE PROCEDURE - The disk extraction procedure may be carried out in a
      manual mode or by using a robotic or automatic sample preparation device. This section
      describes the disk SPE procedure using the equipment outlined in Section 6.10 in its
      simplest, least expensive mode without the use of a robotics systems.  The manual mode
      described below was used to collect data presented in Section 17.

      11.4.1  SAMPLE PREPARATION - Prepare the sample as given in Section 11.2.

      11.4.2  DISK CLEANUP - Assemble the extraction glassware onto the vacuum manifold,
             placing disks on a support screen between the funnel and base. Add a 5 mL
             aliquot of 1:1 mixture of ethyl acetate (EtAc) and methylene chloride (MeCl2)
             (1:1 MeCl2/EtAc), drawing about half through the disk, and allowing the solvent
             to soak the disk for about a minute. Draw the remaining solvent through the disk
             to waste until the disk is dry of solvent.

      11.4.3  DISK CONDITIONING - The conditioning step is critical for recovery of
             analytes and can have a marked effect on method precision and accuracy. If the
             disk goes dry during the conditioning phase, the conditioning must be started
             over.  Once the conditioning has begun, the disk must not go dry until the last
             portion of the sample passes, because analyte and surrogate recoveries may be
             affected.  The analyst should note premature drying of the solid phase, because  the
             sample may require re-extraction due to low surrogate recoveries. During
             conditioning, it is not unusual for the middle of the solid phase disk to form a
             wrinkle. This typically does not adversely affect extraction.

             11.4.3.1 CONDITIONING WITH METHANOL - Add approximately 10 mL
                     methanol to each disk. Pull about 1 mL of MeOH through the disk and
                     turn off the vacuum temporarily to let  the disk soak for about one
                     minute. Draw most of the remaining MeOH through the disk, but leave
                     a layer of MeOH on the surface of the disk.  The disk must not be
                     allowed to go dry from this point until the end of the sample extraction.

             11.4.3.2 CONDITIONING WITH WATER - Follow the MeOH rinse with two,
                      10 mL aliquots of reagent water, being careful to keep the water level
                     above the disk surface. Turn off the vacuum.

      11.4.4  DISK EXTRACTION - Add sample to the extraction funnel containing the
             conditioned disk and turn on the vacuum.  Do not let the disk go  dry before all
             sample has been extracted.  Drain as much water from the sample container as
             possible. After all of the sample has passed, draw air through the disk by
             maintaining full vacuum (minus 10-15 in Hg) for 10 minutes.  If the disk is dried
             for a period much longer than 10 minutes, there will be a loss of recovery for
             nitrobenzene and the surrogate l,3-dimethyl-2-nitrobenzene. After drying, turn
             off and release the vacuum.
                                     526-27

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       11.4.5 DISK ELUTION - Detach the glassware base from the manifold without
             disassembling the funnel from the base.  Dry the underside of the base.  Insert
             collection tubes into the manifold to catch the extracts as they are eluted from the
             disk.  The collection tube must fit around the drip tip of the base to ensure
             collection of all the eluent. Reattach the base to the manifold.  Add  5 mL of ethyl
             acetate to the empty sample bottle and rinse the inside of the bottle.  Transfer the
             ethyl acetate to the disk and, with vacuum, pull enough ethyl acetate into the disk
             to soak the  sorbent, and allow the solvent to soak the disk for about one minute.
             Pull the remaining solvent slowly through the disk into the collection tube.
             Repeat the rinse with 5 mL MeCl2. Rinse the SPE funnel surface once with a 2-3
             mL aliquot of 1:1 EtAc/MeCl2. Repeat this last rinse of the SPE funnel.  Detach
             glassware from manifold and remove collection tube from the manifold.

       11.4.6 DRYINGOF THE EXTRACT - Proceed with drying the extract, Section 11.3.5.

       11.4.7 EXTRACT CONCENTRATION - Proceed with extract concentration, Section
             11.3.6.

       11.4.8 SAMPLE VOLUME OR WEIGHT DETERMINATION - Proceed with sample
             volume or weight determination, Section 11.3.7.

11.5    ANALYSIS OF SAMPLE EXTRACTS

       11.5.1 Establish operating conditions as described in Section 10.2.2. Confirm that
             retention times, compound separation and resolution are similar to those
             summarized in Table 2 and Figure  1.

       11.5.2 Establish a  valid initial calibration following the procedures outlined in Section
             10.2 or confirm that the calibration is still valid by running a CCC as described in
             Section 10.3. If establishing an initial calibration for the first time, complete the
             IDC as described in Section 9.2.

       11.5.3 Analyze aliquots of field and QC samples at appropriate frequencies (Sect. 9) with
             the GC/MS system using the conditions used for the initial and continuing
             calibrations. At the conclusion of data acquisition, use the same software that was
             used in the  calibration procedure to tentatively identify peaks in predetermined
             retention time windows of interest. Use the data system software to examine the
             ion abundances of components of the chromatogram.

       11.5.4 COMPOUND IDENTIFICATION - Identify a sample component by comparison
             of its mass  spectrum (after background subtraction) to a reference spectrum in the
             user-created data base.

             11.5.4.1  Establish an appropriate retention time window for each target analyte,
                      internal standard and surrogate standard to identify them in QC and Field

                                      526-28

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                             Samples chromatograms. Ideally, the retention time window should be
                             based on measurements of actual retention time variation for each
                             compound in standard solutions collected on each 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
                             Initial Demonstration of Capability may be used to calculate a suggested
                             window size.  However, the experience of the analyst should weigh
                             heavily on the determination of an appropriate retention window size.

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

              11.5.5 EXCEEDING CALIBRATION RANGE - An analyst must not extrapolate
                    beyond the established calibration range.  If an analyte result exceeds the range of
                    the initial calibration curve, the extract may be diluted with ethyl acetate, with the
                    appropriate amount of internal standard added to match the original level, and the
                    diluted extract injected. Acceptable surrogate performance (Sect.  9.9) should be
                    determined from the undiluted sample extract.  Incorporate the dilution factor into
                    final concentration calculations. The dilution will also affect analyte MRLs.

12.    DATA ANALYSIS AND CALCULATIONS

       12.1    Identify method  analytes present in the field and QC samples as described in Section
              11.8.4.  Complete chromatographic resolution is not necessary for accurate and precise
              measurements of analyte concentrations if unique ions with adequate intensities are
              available for quantitation.

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

              12.1.2 In validating this method, concentrations were calculated by measuring the

                                            526-29

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                    characteristic ions listed in Table 2. Other ions may be selected at the discretion of
                    the analyst.

       12.2   Calculate analyte and surrogate concentrations, using the multipoint calibration
             established in Section 10.2. Do not use daily continuing calibration check data to
             quantitate analytes in samples. Adjust the final analyte concentrations to reflect the actual
             sample volume or weight determined in Section 11.3.7 or 11.4.8. Field Sample extracts
             that require dilution should be treated as described in Section 11.5.5.

       12.3   Calculations  should utilize all available digits of precision, but final reported
             concentrations should be rounded to an appropriate number of significant figures.

13.    METHOD PERFORMANCE

       13.1   PRECISION, ACCURACY, AND  MDLs - Method performance data are summarized in
             Section 17. Method detection limits (MDLs) are presented in Table 3 and were
             calculated using the formula in Section 9.2.4. Single laboratory precision and accuracy
             data are presented for reagent water (Sect. 17, Tables 4A and 4B), chlorinated "finished"
             ground water (Sect. 17, Tables 5 A and 5B), and chlorinated "finished" surface water
             (Sect.  17, Tables 6A and 6B).

       13.2   POTENTIAL PROBLEM COMPOUNDS

             13.2.1 MATRIX ENHANCED SENSITIVITY - Cyanazine, and to a lesser extent 2,4,6-
                    trichlorophenol and prometon, tend to exhibit "matrix-induced chromatographic
                    response enhancement."(7"n) Compounds that exhibit this phenomenon often give
                    analytical results that exceed 100 % recovery in fortified extracts at low
                    concentration and in continuing calibration checks. More frequent recalibration is
                    required.  It has been proposed that these compounds are susceptible to GC inlet
                    absorption or thermal degradation so that analytes degrade more when injected in
                    a "cleaner" matrix. The injection of a "dirty" sample extract coats surfaces with
                    matrix components and "protects" the problem compounds from decomposition or
                    adsorption. As a result, a relatively greater response is observed for analytes in
                    sample extracts than in calibration solutions. This effect is minimized by using
                    deactivated injection liners (Sect. 10.2.2.2). The analyst may also choose to
                    condition the injection port  after maintenance by injecting a few aliquots of a field
                    sample extract prior to establishing an initial calibration. Preparation of
                    calibration standards in clean extracts is not allowed.

             13.2.2 COMPOUND DEGRADATION - Method development work indicated that
                    several of the target compounds were unstable when stored in water without
                    preservation. There were various modes of loss. Hydrolysis of 1,2-
                    diphenylhydrazine, terbufos, diazinon, disulfoton and cyanazine was accelerated
                    at low and high pH. In addition, transition metal ions further catalyzed hydrolysis
                    of terbufos, fonofos, and diazinon.  Free chlorine and chloramines degraded 2,4-

                                            526-30

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                    dichlorophenol, terbufos, fonofos, diazinon, and disulfoton. When water samples
                    were not properly preserved, after three days, there was more than 80% loss of
                    some targets, initially fortified at 5 ppb.  Sample preservation conditions (Sect. 8)
                    have been carefully chosen to minimize analyte degradation to acceptable levels
                    during the 14 day sample holding time.

              13.2.3 Inlet liners and/or capillary GC columns that develop active sites can cause a
                    complete loss of prometon and excessive tailing of 2,4-dichlorophenol and 2,4,6-
                    trichlorophenol peaks in the chromatogram.
       13.3   ANALYTE STABILITY STUDIES

             13.3.1 FIELD SAMPLES - Chlorinated surface water samples, fortified with method
                    analytes at 5.0 ug/L, were preserved and stored as required in Section 8. The
                    average of triplicate analyses, conducted on days 0, 3, 7, and 14, are presented in
                    Section 17, Table 7. These data document the 14-day sample holding time.  It is
                    advisable to extract as soon as possible because some compounds exhibit
                    significant losses by 7 days.

             13.3.2 EXTRACTS - Extracts from the day 0 extract holding time study described above
                    were stored below 0 °C  and analyzed on days 0, 6, 13, 20, and 32. The data
                    presented in Section 17, Table 8, document the 28-day extract holding time.

14.     POLLUTION PREVENTION

       14.1   This method utilizes solid phase extraction technology to remove the analytes from water.
             It requires the use of very small volumes of organic solvent and very small quantities of
             pure analytes, thereby minimizing the potential hazards to both the analyst and the
             environment involved with the  use of large volumes of organic solvents in conventional
             liquid-liquid extractions.

       14.2   For information about pollution prevention that may be applicable to laboratory
             operations, consult "Less Is Better: Laboratory Chemical Management for Waste
             Reduction" available form the American Chemical Society's Department of Government
             Relations and Science Policy, 1155  16th Street N.W., Washington, D.C. 20036.

15.     WASTE MANAGEMENT

       15.1   The analytical procedures described in this method generate relatively small amounts of
             waste since only small amounts of reagents and solvents are used. The matrices of
             concern are finished drinking water or source 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

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             controlling all releases from fume hoods and bench operations.  Also, compliance is
             required with any sewage discharge permits and regulations, particularly the hazardous
             waste identification rules and land disposal restrictions. For further information on waste
             management, consult "The Waste Management Manual for Laboratory Personnel" also
             available from the American Chemical Society at the address in Section 14.2.
16     REFERENCES

1.      Glaser, J.A., Foerst, D.L., McKee, G.D., Quave, S.A., and Budde, W.L., "Trace Analyses for
       Wastewaters," Environ. Sci. Technol.. 15 (1981) 1426-1435.

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

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

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

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

6.      Llabres, C.M., Ahearn, D.G. "Antimicrobial Activities of N-Chloramines and Diazolidinyl
       Urea," Applied and Environmental Microbiology, 49, (1985), 370-373.

7.      Erney, D.R., Gillespie, A.M., Gilvydis, D.M., and Poole,  C.F., "Explanation of the Matrix-
       Induced Chromatographic Response Enhancement of Organophosphorous Pesticides During
       Open Tubular Column Gas Chromatography with Splitless or Hot On-Column  Injection and
       Flame Photometric Detection." J. Chromatogr.. 638 (1993) 57-63.

8.      Mol, H.G.J., Althuizen, M., Janssen, H., and Cramers, C.A., Brinkman, U.A.Th.,
       "Environmental Applications of Large Volume Injection in Capillary GC Using PTV Injectors,"
       J. High Resol. Chromatogr.. 19 (1996) 69-79.

9.      Erney, D.R., Pawlowski, T.M., Poole, C.F., "Matrix Induced Peak Enhancement of Pesticides in
       Gas Chromatography," J. High Resol. Chromatogr.. 20 (1997) 375-378.

10.     Hajslova, J., Holadova, K. , Kocourek, V., Poustka, J., Godula, M., Cuhra, P., Kempny, M.,
       "Matrix Induced Effects: A Critical  Point in the Gas Chromatographic Analysis of Pesticide

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      Residues," J. Chromatogr.. 800 (1998) 283-295.

11.    Wylie, P., Uchiyama, M., "Improved Gas Chromatographic Analysis of Organophosphorous
      Pesticides with Pulsed Splitless Injection," J. AOAC International. 79, 2, (1996) 571-577.
                                            526-33

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17.   TABLES. DIAGRAMS. FLOWCHARTS. AND VALIDATION DATA

TABLE 1.    ION ABUNDANCE CRITERIA FOR BIS(PERFLUOROPHENYL)PHENYL
             PHOSPHINE, (DECAFLUOROTRIPHENYL PHOSPHINE, DFTPP)
Mass
(M/z)
51
68
70
127
197
198
199
275
365
441
442
443
Relative Abundance Criteria
10-80% of the base peak
<2% of Mass 69
<2% of Mass 69
10-80% of the base peak
<2% of Mass 98
Base peak or >50% of Mass 442
5-9% of Mass 198
10-60% of the base peak
>1% of the base peak
Present and 50% of Mass 198
15-24% of Mass 442
Purpose of Checkpoint1
Low-mass sensitivity
Low-mass resolution
Low-mass resolution
Low- to mid-mass resolution
Mid-mass resolution
Mid-mass resolution and sensitivity
Mid-mass resolution and isotope ratio
Mid- to high-mass sensitivity
Baseline threshold
High-mass resolution
High-mass resolution and sensitivity
High-mass resolution and isotope ratio
JA11 ions are used primarily to check the mass measuring accuracy of the mass spectrometer and data
system, and this is the most important part of the performance test. The three resolution checks, which
include natural abundance isotope ratios, constitute the next most important part of the performance test.
The correct setting of the baseline threshold, as indicated by the presence of low intensity ions, is the
next most important part of the performance test. Finally, the ion abundance ranges are designed to
encourage some standardization to fragmentation patterns.
                                          526-34

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TABLE 2.   RETENTION TIMES (RTs), SUGGESTED QUANTITATION IONS (QIs), AND
           INTERNAL STANDARD REFERENCE
Peak #a
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Analyte
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydrazine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
Acenaphthene-6?10 (IS#1)
Phenanthrene-J10 (IS#2)
Chrysene-J12 (IS#3)
l,3-Dimethyl-2-Nitrobenzene (SURR)
Triphenylphosphate (SURR)
Peak
Label in
Figure #1
1
2
4
6
7
8
9
11
12
13
14
5
10
16
O
15
RTb
(min)
6.33
7.70
10.81
15.08
16.64
17.08
17.14
17.29
17.51
18.39
19.73
12.88
17.20
24.98
7.98
24.29
Quanti-
tation
Ion
77
162
196
182
225
231
246
179
88
146
225
164
188
240
151
326
IS#
Ref.
1
1
1
2
2
2
2
2
2
2
2
-
-
-
1
O
a- Number refers to peak number in Figure 1.
b- Column: 30 m X 0.25 mm i.d. DBS-MS (J&W), 0.25 urn film thickness.
                                      526-35

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TABLE 3.    METHOD DETECTION LIMITS IN REAGENT WATER FOR SDVB DISK AND
             CARTRIDGE EXTRACTION PROCEDURES
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
Disk Extraction
Spiking Cone.
(ug/L)
0.05
0.05
0.05
0.20
0.10
0.05
0.05
0.10
0.10
0.05
0.05
MDLa
(ug/L)
0.015
0.012
0.012
0.028
0.035
0.017
0.022
0.015
0.024
0.015
0.025
Cartridge Extraction
Spiking Cone.
(ug/L)
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
MDLa
(ug/L)
0.09
0.04
0.14
0.10
0.14
0.05
0.06
0.03
0.05
0.10
0.09
aMethod detection limits samples were extracted and analyzed over 3 days for 7 replicates following the
procedure outlined in Section 9.2.4.
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TABLE 4A.   PRECISION, ACCURACY AND SENSITIVITY DATA FOR METHOD ANALYTES
              FORTIFIED AT 0.5 AND 20 UG/L IN REAGENT WATER EXTRACTED WITH SDVB
              DISKS
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
l,3-Dimethyl-2-Nitrobenzene(SUR)c
Triphenylphosphate (SUR)C
Concentration= 0.5 ug/L,
n=7
Mean %
Recovery
106
114
136
121
138
111
104
101
105
124
153
86.2
106
%RSDa
3.8
1.9
2.3
2.5
2.3
2.7
2.0
2.5
2.4
2.9
2.5
2.6
2.6
S/N
Ratio b
159
71
134
25
42
71
138
14
103
67
10
NC
NC
Concentration = 20 ug/L,
n=7
Mean %
Recovery
81.5
97.6
104
103
101
91.4
106
98.3
95.0
98.9
104
84.2
105
%RSDa
5.6
4.3
3.4
3.7
3.8
4.0
4.4
4.7
4.8
4.0
4.6
4.6
5.2
""Relative Standard Deviation = (Standard Deviation/Recovery)* 100.
bSignal-to-noise ratios were calculated for each peak by dividing the peak height for each compound by the peak-
to-peak noise, which was determined for each component from the method blank over a period of time equal to
the full peak width in the target analyte's retention time window.
Surrogate fortification concentration of all samples was 5 ug/L.
                                             526-37

-------
TABLE 4B.  PRECISION AND ACCURACY DATA FOR METHOD ANALYTES FORTIFIED
             AT 0.5 AND 20 UG/L IN REAGENT WATER EXTRACTED WITH SDVB
             CARTRIDGES
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
l,3-Dimethyl-2-Nitrobenzene(SUR)b
Triphenylphosphate (SUR)b
Concentration = 0.5 ug/L,
n=7
Mean %
Recovery
86.3
104
129
96.9
148
115
101
104
106
125
147
81.7
107
%RSDa
6.9
7.3
3.8
16
3.2
2.8
3.8
3.4
3.0
3.0
5.6
4.1
7.5
Concentration = 20 ug/L,
n=7
Mean %
Recovery
73.4
83.8
92.9
123
100
85.0
90.1
91.1
85.5
91.3
101
80.2
108
%RSDa
3.7
3.3
3.0
3.2
0.8
1.8
1.9
1.4
1.7
1.2
1.2
3.0
3.0
""Relative Standard Deviation = (Standard Deviation/Recovery)* 100.
bSurrogate fortification concentration of all samples was 5 ug/L.
                                           526-38

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TABLE 5A.  PRECISION AND ACCURACY DATA FOR METHOD ANALYTES FORTIFIED
             AT 0.5, AND 20 UG/L IN GROUND WATER EXTRACTED WITH SDVB DISKS
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
l,3-Dimethyl-2-Nitrobenzene(SUR)b
Triphenylphosphate (SUR)b
Concentration = 0.5 ug/L,
n = 7
Mean %
Recovery
110
113
148
134
152
119
105
110
113
130
163
86.3
105
%RSDa
4.7
3.0
2.0
3.8
2.4
1.6
2.4
1.5
2.5
2.1
2.3
4.8
2.9
Concentration = 20 ug/L,
n = 7
Mean %
Recovery
83.5
96.5
103
102
101
93.4
105
97.6
95.1
98.3
104
83.8
106
%RSDa
5.3
5.0
4.1
4.0
3.8
3.5
3.7
3.7
4.2
3.7
3.8
5.5
4.0
""Relative Standard Deviation = (Standard Deviation/Recovery)* 100.
bSurrogate fortification concentration of all samples was 5 ug/L.
                                           526-39

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TABLE 5B.  PRECISION AND ACCURACY DATA FOR METHOD ANALYTES FORTIFIED
             AT 0.5, 5.0 AND 20 UG/L IN GROUND WATER EXTRACTED WITH SDVB
             CARTRIDGES
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
1 ,3-Dimethyl-2-Nitr obenzene
(SUR)b
Triphenylphosphate (SUR)b
Concentration =
0.5 ug/L, n = 7
Mean %
Recovery
114
110
136
122
144
120
107
105
108
129
160
86.7
119
%RSDa
5.4
3.4
4.1
4.3
3.3
3.0
3.0
2.4
3.8
4.5
3.1
6.3
4.3
Concentration =
5.0 ug/L, n = 7
Mean %
Recovery
87.7
89.8
102
84.8
103
87.1
87.9
88.7
93.3
103
106
86.3
123
%RSDa
3.9
3.9
3.8
3.2
2.9
4.2
3.5
3.1
3.7
3.7
3.6
3.3
3.4
Concentration =
20 ug/L, n = 7
Mean %
Recovery
84.1
89.1
98.3
90.4
100
84.9
90.8
91.6
88.6
94.2
98.6
84.1
111
%RSDa
1.9
2.2
1.4
3.7
2.3
2.4
2.4
2.3
3.1
1.1
3.6
4.6
14
3Relative Standard Deviation = (Standard Deviation/Recovery)* 100.
bSurrogate fortification concentration of all samples was 5 ug/L.
                                           526-40

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TABLE 6A.  PRECISION AND ACCURACY DATA FOR METHOD ANALYTES FORTIFIED
             AT 0.5, 5.0 AND 20 UG/L IN SURFACE WATER EXTRACTED WITH SDVB
             DISKS
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
1 ,3-Dimethyl-2-Nitr obenzene
(SUR)b
Triphenylphosphate (SUR)b
Concentration =
0.5 ug/L, n = 7
Mean %
Recovery
105
111
143
118
136
109
98.9
102
105
124
151
82.9
101
%RSDa
3.8
4.0
2.8
2.4
3.6
3.0
3.8
3.6
3.4
3.4
3.2
4.5
4.5
Concentration =
5.0 ug/L, n = 7
Mean %
Recovery
72.4
81.2
90.8
105
102
85.7
83.0
83.7
81.2
89.2
105
77.4
98.2
%RSDa
4.4
4.0
4.2
4.5
3.1
4.6
4.2
3.5
4.2
3.6
3.9
4.4
3.6
Concentration =
20 ug/L, n = 7
Mean %
Recovery
76.7
89.9
92.4
88.3
89.5
80.2
89.1
86.1
86.6
89.4
93.6
83.9
98.8
%RSDa
4.1
4.8
4.0
3.9
3.9
3.4
4.0
4.1
3.7
3.4
3.9
3.9
4.3
3Relative Standard Deviation = (Standard Deviation/Recovery)* 100.
bSurrogate fortification concentration of all samples was 5 ug/L.
                                          526-41

-------
TABLE 6B.  PRECISION AND ACCURACY DATA FOR METHOD ANALYTES FORTIFIED
             AT 0.5 AND 20 UG/L IN SURFACE WATER EXTRACTED WITH SDVB
             CARTRIDGES
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
l,3-Dimethyl-2-Nitrobenzene(SUR)b
Triphenylphosphate (SUR)b
Concentration = 0.5 ug/L,
n = 7
Mean %
Recovery
91.7
113
135
107
158
128
109
112
109
132
158
83.0
104
%RSDa
6.6
4.9
4.0
9.9
3.3
3.0
2.3
3.7
3.0
2.8
1.7
5.3
1.9
Concentration = 20 ug/L,
n = 7
Mean %
Recovery
84.9
89.7
97.2
93.7
101
89.0
91.6
92.8
90.0
94.6
99.9
85.1
99.1
%RSDa
2.9
2.2
1.8
2.3
1.3
2.1
1.6
1.5
1.6
1.4
1.0
3.8
1.60
3Relative Standard Deviation = (Standard Deviation/Recovery)* 100.
bSurrogate fortification concentration of all samples was 5 ug/L.
                                          526-42

-------
TABLE 7.    SAMPLE HOLDING TIME DATA3 FOR SAMPLES FROM A CHLORINATED
             SURFACE WATER, FORTIFIED WITH METHOD ANALYTES AT 5 UG/L,
             AND PRESERVED ACCORDING TO SECTION 8.
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
DayO
% Rec.
83.5
97.2
110
98.8
104
96.7
94.1
93.0
90.8
100
126
Day 3
% Rec.
82.4
92.6
102
93.9
97.7
79.3
88.0
86.7
84.7
93.3
119
Day?
% Rec.
76.7
86.9
97.3
87.5
93.1
69.1
84.8
83.4
81.5
90.5
112
Day 14
% Rec.
88.1
98.1
108
97.2
102
65.4
93.1
91.3
89.1
97.6
125
3Storage stability is expressed as a percent recovery value. Each percent recovery value represents the mean of 3
replicate analyses. Relative Standard Deviations ([Standard Deviation/Recovery]* 100) for replicate analyses
were all less than 13.8 %.
                                           526-43

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TABLE 8.   EXTRACT HOLDING TIME DATA3 FOR SAMPLES FROM A CHLORINATED
             SURFACE WATER, FORTIFIED WITH METHOD ANALYTES AT 5 UG/L,
             AND PRESERVED ACCORDING TO SECTION 8.
Compound
Nitrobenzene
2,4-Dichlorophenol
2,4,6-Trichlorophenol
1 ,2-Diphenylhydr azine
Prometon
Terbufos
Fonofos
Diazinon
Disulfoton
Acetochlor
Cyanazine
l,3-Dimethyl-2-Nitrobenzene(SUR)b
Triphenylphosphate (SUR)b
DayO
%Rec.
83.5
97.2
110
98.8
104
96.7
94.1
93.0
90.8
100
126
79.3
97.9
Day 6
% Rec.
84.7
97.5
110
97.9
104
97.5
95.0
93.0
91.9
100
125
78.5
96.6
Day 13
% Rec.
85.2
96.2
108
97.9
103
97.9
94.3
93.6
92.9
99.8
124
78.7
96.7
Day 20
%Rec.
85.5
96.7
107
97.0
103
98.6
95.3
94.3
94.6
99.8
122
78.5
97.8
Day 32
% Rec.
80.5
95.9
112
98.3
101
89.5
97.3
93.0
93.5
98.7
123
77.1
93.4
""Extracts were stored at less than 0 °C and reinjected periodically.  Each table value represents the mean of 3
replicate analyses. Relative Standard Deviations ([Standard Deviation/Recovery]* 100) for replicate analyses
were all less than 5.7 %.
                                            526-44

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TABLE 9.    INITIAL DEMONSTRATION OF CAPABILITY (IDC) REQUIREMENTS
 Method
 Reference
Requirement
Specification and
Frequency
Acceptance Criteria
 Section
 9.2.1
Initial
Demonstration of
Low Method
Background
Analyze LRB prior to any
other IDC steps
Demonstrate that all target
analytes are below V3 the
reporting limit or lowest CAL
standard, and that possible
interference from extraction
media do not prevent the
identification and quantification
of method analytes.
 Section
 9.2.2
Initial
Demonstration of
Precision (IDP)
Analyze 4-7 replicate LFBs
fortified at midrange
concentration.
%RSD must be • 20%
 Section
 9.2.3
Initial
Demonstration of
Accuracy
Calculate average recovery for
replicates used in IDP
Mean recovery 70-130% of true
value.
 Section
 9.2.4
Method Detection
Limit (MDL)
Determination
Over a period of three days,
prepare a minimum of 7
replicate LFBs fortified at a
concentration estimated to be
near the MDL. Analyze the
replicates through all steps of
the analysis.  Calculate the
MDL using the equation in
Section 9.2.4.
Note: Data from MDL replicates
are not required to meet method
precision and accuracy criteria. If
the MDL replicates are fortified at
a low enough concentration, it is
likely that they will not meet
precision and accuracy criteria.
                                             526-45

-------
TABLE 10.   QUALITY CONTROL REQUIREMENTS (SUMMARY)
 Method
 Reference
Requirement
Specification and Frequency
Acceptance Criteria
 Section
 10.2.1
MS Tune Check
Analyze DFTPP to verify MS tune
each time the instrument is
calibrated.
Criteria are given in Table 1.
 Section
 10.2
Initial Calibration
Use internal standard calibration
technique to generate an average
RRF or first or second order
calibration curve. Use at least 5
standard concentrations.
When each calibration standard
is calculated as an unknown
using the calibration curve, the
result must be 70-130% of the
true value for all except the
lowest standard, which must be
50-150% of the true value.
 Section 9.4
Laboratory Reagent
Blank (LRB)
Daily, or with each extraction
batch of up to 20 samples,
whichever is more frequent.
Demonstrate that all target
analytes are below V3 the
method reporting limit or lowest
CAL standard, and that possible
interferences do not prevent
quantification of method
analytes.
If targets exceed V3 the MRL,
results for all subject analytes in
extraction batch are invalid.
 Section
 10.3
Continuing
Calibration Check
(CCC)
Verify initial calibration by
analyzing a calibration standard at
the beginning of each analysis
batch prior to analyzing samples,
after every 10 samples, and after
the last sample.

Low CCC - near MRL
Mid CCC - near midpoint in initial
calibration curve
High CCC -  near highest
calibration standard
1) The result for each analyte
must be 70-130% of the true
value for all but the lowest
standard. The lowest standard
must be 50-150% of the true
value.
2) The peak area of internal
standards must be 50-150% of
the average peak area calculated
during the initial calibration.
Results for analytes that do not
meet IS criteria or are not
bracketed by acceptable CCCs
are invalid.
                                                526-46

-------
Method
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Section 9.6
Laboratory Fortified
Blank (LFB)
One LFB is required daily or for
each extraction batch of up to 20
field samples.  Rotate the fortified
concentration between low,
medium, and high amounts.
Results of LFB analyses at
medium and high fortification
must be 70-130% of the true
value for each analyte and
surrogate. LFB Results of the
low level LFB must be 50-160%
of the true value.
Section 9.8
Internal Standard
Acenaphthene-J10
phenanthrene-6?10 (IS#2), and
chrysene-t/12 (IS#3), are added to
all standards and sample extracts.
Peak area counts for all ISs in
LFBs, LRBs, and sample
extracts must be within 50-
150% of the average peak area
calculated during the initial
calibration. If ISs do not meet
criteria, corresponding target
results are invalid.
Section 9.9
Surrogate Standards
Surrogate standards, 1,3-
dimethyl-2-nitrobenzene and
triphenylphosphate, are added to
all calibration standards and
samples, including QC samples.  If
nitrobenzene is not to be included
on the target list, then the surrogate
l,3-dimethyl-2-nitrobenzene is not
required.
Surrogate recovery must be 70-
130% of the true value. If
surrogate fails this criterion,
report all results for sample as
suspect/surrogate recovery.
Section
9.10
Laboratory Fortified
Sample Matrix (LFM)
and Laboratory
Fortified Matrix
Duplicate (LFMD)
Analyze one LFM per analysis
batch (20 samples or less) fortified
with method analytes at a
concentration close to but greater
than the native concentration.
LFMD should be used in place of
Field Duplicate if frequency of
detects for targets is low.
Recoveries at mid and high
levels not within 70-130% or
low-level recoveries not within
50-150% of the fortified amount
may indicate a matrix effect.
Target analyte RPDs for LFMD
should be ±30% at mid and high
levels of fortification and  ±50%
near MRL.
Section
9.11
Field Duplicates (FD)
Extract and analyze at least one
FD with each extraction batch (20
samples or less). A LFMD may be
substituted for a FD when the
frequency of detects for target
analytes is low.
Target analyte RPDs for FD
should be ±30% at mid and high
levels of fortification and ±50%
near MRL.
Section
9.12
Quality Control
Sample (QCS)
Analyzed QCS quarterly.
Results must be 70-130% of the
expected value.
                                               526-47

-------
Method
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Section 8.4
Sample Holding Time
14 days with appropriate
preservation and storage
Sample results are valid only if
samples are extracted within
sample hold time.
Section 8.4
Extract Holding Time
28 days with appropriate storage
Sample results are valid only if
extracts are analyzed within
extract hold time.
                                               526-48

-------
FIGURE 1. EXAMPLE CHROMATOGRAM FOR METHOD 526.  NUMBERED PEAKS ARE IDENTIFIED IN TABLE 2.
                                                                                 10







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TOO    s.eo   &.to   10.00   11.00  12.00
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      Time (min)
                                                                                                         ioo
                                                                                                                                  25.03
       Figure 1 • Total ion cliroinalograni of snrf;ice water sample exlracl \\il\\ \;trgei compounds, iiilental slandards, ;uid surrogate slatid-irds fortified at 5 ppm
       level in extract,  Peaks with asterisk (*) are interference associated w,i(h the use ofdia/oiidiiivl urea.
                                                                       526-49

-------