4-Methyl-2-pentanone.......................................        13.83
Toluene....................................................        14.18
trans-1,3-Dichloropropene..................................        14.57
Ethyl methacrylate.........................................        14.70
1,1,2-Trichloroethane......................................        14.93
1,3-Dichloropropane........................................        15.18
Tetrachloroethene..........................................        15.22
2-Hexanone.................................................        15.30
Dibromochloromethane.......................................        15.68
1,2-Dibromoethane..........................................        15.90
Chlorobenzene..............................................        16.78
Ethylbenzene...............................................        16.82
1,1,1,2-Tetrachloroethane..................................        16.87
m+p-Xylene.................................................        17.08
o-Xylene...................................................        17.82
Bromoform..................................................        18.27
Bromofluorobenzene.........................................        18.80
1,1,2,2-Tetrachloroethane..................................        18.98
1,2,3-Trichloropropane.....................................        19.08
trans-1,4-Dichloro-2-butene................................        19.12
------------------------------------------------------------------------
Column: 75 m x 0.53 mm ID x 3.0 [mu]m wide-bore DB-624.
Conditions: 40[deg]C for 4 min, 9[deg]C/min to 200[deg]C, 20[deg]C/min
  (or higher) to 250[deg]C, hold for 20 min at 250[deg]C to remove
  water.
Carrier gas flow rate: 6-7 mL/min at 40[deg]C.
Inlet split ratio: 3:1.
Interface split ratio: 7:2.

              Table 4--BFB Key m/z Abundance Criteria \ 1\
------------------------------------------------------------------------
                    m/z                          Abundance criteria
------------------------------------------------------------------------
50........................................  15-40% of m/z 95.
75........................................  30-60% of m/z 95.
95........................................  Base Peak, 100% Relative
                                             Abundance.
96........................................  5-9% of m/z 95.
173.......................................  <2% of m/z 174.
174.......................................  >50% of m/z 95.
175.......................................  5-9% of m/z 174.
176.......................................  >95% but <101% of m/z 174.
177.......................................  5-9% of m/z 176.
------------------------------------------------------------------------
\1\ Abundance criteria are for a quadrupole mass spectrometer; contact
  the manufacturer for criteria for other types of mass spectrometers.

                               Table 5--Suggested Surrogate and Internal Standards
----------------------------------------------------------------------------------------------------------------
                                                                 Retention time                      Secondary m/
                           Analyte                                 (min) \1\         Primary m/z         z's
----------------------------------------------------------------------------------------------------------------
Benzene-d6...................................................              10.95                 84  ...........
4-Bromofluorobenzene.........................................              18.80                 95     174, 176
Bromochloromethane...........................................               9.88                128  49, 130, 51
2-Bromo-1-chloropropane......................................              14.80                 77      79, 156
2-Butanone-d5................................................               9.33                 77  ...........
Chloroethane-d5..............................................               4.63                 71  ...........
Chloroform-\13\C.............................................              10.00                 86  ...........
1,2-Dichlorobenzene-d4.......................................  .................                152  ...........
1,4-Dichlorobutane...........................................              18.57                 55       90, 92
1,2-Dichloroethane-d4........................................              10.88                102  ...........
1,1-Dichloroethene-d2........................................               6.30                 65  ...........
1,2-Dichloropropane-d6.......................................              12.27                 67  ...........
trans-1,3-Dichloropropene-d4.................................              14.50                 79  ...........
1,4-Difluorobenzene..........................................  .................                114       63, 88
Ethylbenzene-d10.............................................              16.77                 98  ...........
Fluorobenzene................................................  .................                 96           70
2-Hexanone-d5................................................              15.30                 63  ...........
Pentafluorobenzene...........................................  .................                168  ...........
1,1,2,2-Tetrachloroethane-d2.................................              18.93                 84  ...........
Toluene-d8...................................................              14.13                100  ...........
Vinyl chloride-d3............................................               3.87                 65
----------------------------------------------------------------------------------------------------------------
\1\ For chromatographic conditions, see the footnote to Table 3.

          Table 6--Characteristic m/z's for Purgeable Organics
------------------------------------------------------------------------
             Analyte                 Primary m/z       Secondary m/z's
------------------------------------------------------------------------
Chloromethane...................                 50  52.
Bromomethane....................                 94  96.
Vinyl chloride..................                 62  64.
Chloroethane....................                 64  66.
Methylene chloride..............                 84  49, 51, and 86.
Trichlorofluoromethane..........                101  103.
1,1-Dichloroethene..............                 96  61 and 98.
1,1-Dichloroethane..............                 63  65, 83, 85, 98, and
                                                      100.
trans-1,2-Dichloroethene........                 96  61 and 98.
Chloroform......................                 83  85.
1,2-Dichloroethane..............                 98  62, 64, and 100.
1,1,1-Trichloroethane...........                 97  99, 117, and 119.
Carbon tetrachloride............                117  119 and 121.
Bromodichloromethane............                 83  127, 85, and 129.
1,2-Dichloropropane.............                 63  112, 65, and 114.
trans-1,3-Dichloropropene.......                 75  77.
Trichloroethene.................                130  95, 97, and 132.
Benzene.........................                 78  ...................
Dibromochloromethane............                127  129, 208, and 206.
1,1,2-Trichloroethane...........                 97  83, 85, 99, 132,
                                                      and 134.
cis-1,3-Dichloropropene.........                 75  77.
2-Chloroethylvinyl ether........                106  63 and 65.
Bromoform.......................                173  171, 175, 250, 252,
                                                      254, and 256.
1,1,2,2-Tetrachloroethane.......                168  83, 85, 131, 133,
                                                      and 166.
Tetrachloroethene...............                164  129, 131, and 166.
Toluene.........................                 92  91.
Chlorobenzene...................                112  114.
Ethyl benzene...................                106  91.
1,3-Dichlorobenzene.............                146  148 and 111.
1,2-Dichlorobenzene.............                146  148 and 111.
1,4-Dichlorobenzene.............                146  148 and 111.
------------------------------------------------------------------------

                                      Table 7--LCS (Q), DOC (S and X), and MS/MSD (P and RPD) Acceptance Criteria 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Range for X (%)
                         Analyte                            Range for Q (%)    Limit for s (%)                       Range for P (%)     Limit for RPD
--------------------------------------------------------------------------------------------------------------------------------------------------------
Benzene..................................................             65-135                 33             75-125             37-151                 61
Benzene-d6...............................................  .................  .................  .................             70-130  .................
Bromodichloromethane.....................................             65-135                 34             50-140             35-155                 56
Bromoform................................................             70-130                 25             57-156             45-169                 42
Bromomethane.............................................             15-185                 90              D-206              D-242                 61
2-Butanone-d5............................................  .................  .................  .................             60-140  .................
Carbon tetrachloride.....................................             70-130                 26             65-125             70-140                 41
Chlorobenzene............................................             65-135                 29             82-137             37-160                 53
Chloroethane.............................................             40-160                 47             42-202             14-230                 78
Chloroethane-d5..........................................  .................  .................  .................             60-140  .................
2-Chloroethylvinyl ether.................................              D-225                130              D-252              D-305                 71
Chloroform...............................................             70-135                 32             68-121             51-138                 54
Chloroform-\13\C.........................................  .................  .................  .................             70-130  .................
Chloromethane............................................              D-205                472              D-230              D-273                 60
Dibromochloromethane.....................................             70-135                 30             69-133             53-149                 50
1,2-Dichlorobenzene......................................             65-135                 31             59-174             18-190                 57
1,2-Dichlorobenzene-d4...................................  .................  .................  .................             70-130  .................
1,3-Dichlorobenzene......................................             70-130                 24             75-144             59-156                 43
1,4-Dichlorobenzene......................................             65-135                 31             59-174             18-190                 57
1,1-Dichloroethane.......................................             70-130                 24             71-143             59-155                 40
1,2-Dichloroethane.......................................             70-130                 29             72-137             49-155                 49
1,2-Dichloroethane-d4....................................  .................  .................  .................             70-130  .................
1,1-Dichloroethene.......................................             50-150                 40             19-212              D-234                 32
1,1-Dichloroethene-d2....................................  .................  .................  .................             70-130  .................
trans-1,2-Dichloroethene.................................             70-130                 27             68-143             54-156                 45
1,2-Dichloropropane......................................             35-165                 69             19-181              D-210                 55
1,2-Dichloropropane-d6...................................  .................  .................  .................             60-140  .................
cis-1,3-Dichloropropene..................................             25-175                 79              5-195              D-227                 58
trans-1,3-Dichloropropene................................             50-150                 52             38-162             17-183                 86
trans-1,3-Dichloropropene-d4.............................  .................  .................  .................             70-130  .................
Ethyl benzene............................................             60-140                 34             75-134             37-162                 63
2-Hexanone-d5............................................  .................  .................  .................             60-140  .................
Methylene chloride.......................................             60-140                192              D-205              D-221                 28
1,1,2,2-Tetrachloroethane................................             60-140                 36             68-136             46-157                 61
1,1,2,2-Tetrachloroethane-d2.............................  .................  .................  .................             70-130  .................
Tetrachloroethene........................................             70-130                 23             65-133             64-148                 39

Toluene..................................................             70-130                 22             75-134             47-150                 41
Toluene-d8...............................................  .................  .................  .................             70-130  .................
1,1,1-Trichloroethane....................................             70-130                 21             69-151             52-162                 36
1,1,2-Trichloroethane....................................             70-130                 27             75-136             52-150                 45
Trichloroethene..........................................             65-135                 29             75-138             70-157                 48
Trichlorofluoromethane...................................             50-150                 50             45-158             17-181                 84
Vinyl chloride...........................................              5-195                100              D-218              D-251                 66
Vinyl chloride-d3........................................  .................  .................  .................             70-130  .................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Criteria were calculated using an LCS concentration of 20 [mu]g/L
Q = Percent recovery in calibration verification/LCS (Section 8.4)
s = Standard deviation of percent recovery for four recovery measurements (Section 8.2.4)
X = Average percent recovery for four recovery measurements (Section 8.2.4)
P = Percent recovery for the MS or MSD (Section 8.3.3)
D = Detected; result must be greater than zero
Notes:
1. Criteria for pollutants are based upon the method performance data in Reference 4. Where necessary, limits for recovery have been broadened to assure
  applicability to concentrations below those used to develop Table 7.
2. Criteria for surrogates are from EPA CLP SOM01.2D.

                          Table 8--Recovery and Precision as Functions of Concentration
----------------------------------------------------------------------------------------------------------------
                                                                    Single analyst        Overall precision, S'
              Analyte                 Recovery, X' ([mu]g/L)   precision, sr' ([mu]g/L)         ([mu]g/L)
----------------------------------------------------------------------------------------------------------------
Benzene............................  0.93C+2.00..............  20.26 X-1.74............  0.25 X-1.33
Bromodichloromethane...............  1.03C-1.58..............  0.15 X+0.59.............  0.20 X+1.13
Bromoform..........................  1.18C-2.35..............  0.12 X+0.36.............  0.17 X+1.38
Bromomethane \a\...................  1.00C...................  0.43 X..................  0.58 X
Carbon tetrachloride...............  1.10C-1.68..............  0.12 X+0.25.............  0.11 X+0.37
Chlorobenzene......................  0.98C+2.28..............  0.16 X-0.09.............  0.26 X-1.92
Chloroethane.......................  1.18C+0.81..............  0.14 X+2.78.............  0.29 X+1.75
2-Chloroethylvinyl ether \a\.......  1.00C...................  0.62 X..................  0.84 X
Chloroform.........................  0.93C+0.33..............  0.16 X+0.22.............  0.18 X+0.16
Chloromethane......................  1.03C+0.81..............  0.37 X+2.14.............  0.58 X+0.43
Dibromochloromethane...............  1.01C-0.03..............  0.17 X-0.18.............  0.17 X+0.49
1,2-Dichlorobenzene \b\............  0.94C+4.47..............  0.22 X-1.45.............  0.30 X-1.20
1,3-Dichlorobenzene................  1.06C+1.68..............  0.14 X-0.48.............  0.18 X-0.82
1,4-Dichlorobenzene \b\............  0.94C+4.47..............  0.22 X-1.45.............  0.30 X-1.20
1,1-Dichloroethane.................  1.05C+0.36..............  0.13 X-0.05.............  0.16 X+0.47
1,2-Dichloroethane.................  1.02C+0.45..............  0.17 X-0.32.............  0.21 X-0.38
1,1-Dichloroethene.................  1.12C+0.61..............  0.17 X+1.06.............  0.43 X-0.22
trans-1,2,-Dichloroethene..........  1.05C+0.03..............  0.14 X+0.09.............  0.19 X+0.17
1,2-Dichloropropane \a\............  1.00C...................  0.33 X..................  0.45 X
cis-1,3-Dichloropropene \a\........  1.00C...................  0.38 X..................  0.52 X
trans-1,3-Dichloropropene \a\......  1.00C...................  0.25 X..................  0.34 X
Ethyl benzene......................  0.98C+2.48..............  0.14 X+1.00.............  0.26 X-1.72
Methylene chloride.................  0.87C+1.88..............  0.15 X+1.07.............  0.32 X+4.00
1,1,2,2-Tetrachloroethane..........  0.93C+1.76..............  0.16 X+0.69.............  0.20 X+0.41
Tetrachloroethene..................  1.06C+0.60..............  0.13 X-0.18.............  0.16 X-0.45
Toluene............................  0.98C+2.03..............  0.15 X-0.71.............  0.22 X-1.71
1,1,1-Trichloroethane..............  1.06C+0.73..............  0.12 X-0.15.............  0.21 X-0.39
1,1,2-Trichloroethane..............  0.95C+1.71..............  0.14 X+0.02.............  0.18 X+0.00
Trichloroethene....................  1.04C+2.27..............  0.13 X+0.36.............  0.12 X+0.59
Trichlorofluoromethane.............  0.99C+0.39..............  0.33 X-1.48.............  0.34 X-0.39
Vinyl chloride.....................  1.00C...................  0.48 X..................  0.65 X
----------------------------------------------------------------------------------------------------------------
X' = Expected recovery for one or more measurements of a sample containing a concentration of C, in [mu]g/L.
Sr' = Expected single analyst standard deviation of measurements at an average concentration found of X, in
  [mu]g/L.
S' = Expected interlaboratory standard deviation of measurements at an average concentration found of X, in
  [mu]g/L.
C = True value for the concentration, in [mu]g/L.
X = Average recovery found for measurements of samples containing a concentration of C, in [mu]g/L.
\a\ Estimates based upon the performance in a single laboratory (References 4 and 16).
\b\ Due to coelutions, performance statements for these isomers are based upon the sums of their concentrations.

19. Figures
BILLING CODE 6560-50-P
[GRAPHIC] [TIFF OMITTED] TP19FE15.014

BILLING CODE 6560-50-C

20. Glossary
    These definitions and purposes are specific to this method, but
have been conformed to common usage to the extent possible.
    20.1 Units of weight and measure and their abbreviations
    [GRAPHIC] [TIFF OMITTED] TP19FE15.015

20.1.1 Symbols
[deg]C degrees Celsius
[mu]g microgram
[mu]L microliter
< less than
> greater than
% percent
20.1.2 Abbreviations (in alphabetical order)
cm centimeter
g gram
h hour
ID inside diameter
in. inch
L liter
M Molecular ion
m mass
mg milligram
min minute
mL milliliter
mm millimeter
ms millisecond
m/z mass-to-charge ratio
N normal; gram molecular weight of solute divided by hydrogen
equivalent of solute, per liter of solution
ng nanogram
pg picogram
ppb part-per-billion
ppm part-per-million
ppt part-per-trillion
psig pounds-per-square inch gauge
v/v volume per unit volume
w/v weight per unit volume
20.2 Definitions and acronyms (in alphabetical order)
    Analyte--A compound tested for by this method. The analytes are
listed in Tables 1 and 2.
    Analyte of interest--An analyte of interest is an analyte required
to be

determined by a regulatory/control authority or in a permit, or by a
client.
    Analytical batch--The set of samples analyzed on a given instrument
during a 12-hour period that begins and ends with analysis of a
calibration verification/LCS. See Section 8.4.
    Blank--An aliquot of reagent water that is treated exactly as a
sample including exposure to all glassware, equipment, solvents,
reagents, internal standards, and surrogates that are used with
samples. The blank is used to determine if analytes or interferences
are present in the laboratory environment, the reagents, or the
apparatus. See Section 8.5.
    Calibration--The process of determining the relationship between
the output or response of a measuring instrument and the value of an
input standard. Historically, EPA has referred to a multi-point
calibration as the ``initial calibration,'' to differentiate it from a
single-point calibration verification.
    Calibration standard--A solution prepared from stock solutions and/
or a secondary standards and containing the analytes of interest,
surrogates, and internal standards. The calibration standard is used to
calibrate the response of the GC/MS instrument against analyte
concentration.
    Calibration verification standard--The laboratory control sample
(LCS) used to verify calibration. See Section 8.4.
    Descriptor--In SIM, the beginning and ending retention times for
the RT window, the m/z's sampled in the RT window, and the dwell time
at each m/z.
    Extracted ion current profile (EICP)--The line described by the
signal at a given m/z.
    Field duplicates--Two samples collected at the same time and place
under identical conditions, and treated identically throughout field
and laboratory procedures. Results of analyses of field duplicates
provide an estimate of the precision associated with sample collection,
preservation, and storage, as well as with laboratory procedures.
    Field blank--An aliquot of reagent water or other reference matrix
that is placed in a sample container in the field, and treated as a
sample in all respects, including exposure to sampling site conditions,
storage, preservation, and all analytical procedures. The purpose of
the field blank is to determine if the field or sample transporting
procedures and environments have contaminated the sample.
    GC--Gas chromatograph or gas chromatography
    Internal standard--A compound added to a sample in a known amount
and used as a reference for quantitation of the analytes of interest
and surrogates. Internal standards are listed in Table 5. Also see
Internal standard quantitation.
    Internal standard quantitation--A means of determining the
concentration of an analyte of interest (Tables 1 and 2) by reference
to a compound added to a sample and not expected to be found in the
sample.
    DOC--Initial demonstration of capability (DOC; Section 8.2); four
aliquots of reagent water spiked with the analytes of interest and
analyzed to establish the ability of the laboratory to generate
acceptable precision and recovery. A DOC is performed prior to the
first time this method is used and any time the method or
instrumentation is modified.
    Laboratory control sample (LCS; laboratory fortified blank (LFB);
on-going precision and recovery sample; OPR)--An aliquot of reagent
water spiked with known quantities of the analytes of interest and
surrogates. The LCS is analyzed exactly like a sample. Its purpose is
to assure that the results produced by the laboratory remain within the
limits specified in this method for precision and recovery. In this
method, the LCS is synonymous with a calibration verification sample
(See Sections 7.4 and 8.4).
    Laboratory fortified sample matrix--See Matrix spike.
    Laboratory reagent blank--See Blank.
    Matrix spike (MS) and matrix spike duplicate (MSD) (laboratory
fortified sample matrix and duplicate)--Two aliquots of an
environmental sample to which known quantities of the analytes of
interest and surrogates are added in the laboratory. The MS/MSD are
prepared and analyzed exactly like a field sample. Their purpose is to
quantify any additional bias and imprecision caused by the sample
matrix. The background concentrations of the analytes in the sample
matrix must be determined in a separate aliquot and the measured values
in the MS/MSD corrected for background concentrations.
    May--This action, activity, or procedural step is neither required
nor prohibited.
    May not--This action, activity, or procedural step is prohibited.
    Method blank (laboratory reagent blank)--See Blank.
    Method detection limit (MDL)--A detection limit determined by the
procedure at 40 CFR part 136, appendix B. The MDLs determined by EPA in
the original version of the method are listed in Table 1. As noted in
Sec. 1.4, use the MDLs in Table 1 in conjunction with current MDL data
from the laboratory actually analyzing samples to assess the
sensitivity of this procedure relative to project objectives and
regulatory requirements (where applicable).
    Minimum level (ML)--The term ``minimum level'' refers to either the
sample concentration equivalent to the lowest calibration point in a
method or a multiple of the method detection limit (MDL), whichever is
higher. Minimum levels may be obtained in several ways: They may be
published in a method; they may be based on the lowest acceptable
calibration point used by a laboratory; or they may be calculated by
multiplying the MDL in a method, or the MDL determined by a laboratory,
by a factor of 3. For the purposes of NPDES compliance monitoring, EPA
considers the following terms to be synonymous: ``quantitation limit,''
``reporting limit,'' and ``minimum level.''
    MS--Mass spectrometer or mass spectrometry.
    Must--This action, activity, or procedural step is required.
    m/z--The ratio of the mass of an ion (m) detected in the mass
spectrometer to the charge (z) of that ion.
    Quality control sample (QCS)--A sample containing analytes of
interest at known concentrations. The QCS is obtained from a source
external to the laboratory or is prepared from standards obtained from
a different source than the calibration standards.
    The purpose is to check laboratory performance using test materials
that have been prepared independent of the normal preparation process.
    Reagent water--Water demonstrated to be free from the analytes of
interest and potentially interfering substances at the MDLs for the
analytes in this method.
    Regulatory compliance limit (or regulatory concentration limit)--A
limit on the concentration or amount of a pollutant or contaminant
specified in a nationwide standard, in a permit, or otherwise
established by a regulatory/control authority.
    Relative retention time (RRT)--The ratio of the retention time of
an analyte to the retention time of its associated internal standard.
RRT compensates for small changes in the GC temperature program that
can affect the absolute retention times of the analyte and internal
standard. RRT is a unitless quantity.
    Relative standard deviation (RSD)--The standard deviation times 100

divided by the mean. Also termed ``coefficient of variation.''
    RF--Response factor. See Section 7.3.3.
    RSD--See relative standard deviation.
    Safety Data Sheet (SDS)--Written information on a chemical's
toxicity, health hazards, physical properties, fire, and reactivity,
including storage, spill, and handling precautions that meet the
requirements of OSHA, 29 CFR 1910.1200(g) and appendix D to Sec.
1910.1200. United Nations Globally Harmonized System of Classification
and Labelling of Chemicals (GHS), third revised edition, United
Nations, 2009.
    Selected Ion Monitoring (SIM)--An MS technique in which a few m/z's
are monitored. When used with gas chromatography, the m/z's monitored
are usually changed periodically throughout the chromatographic run to
correlate with the characteristic m/z's for the analytes, surrogates,
and internal standards as they elute from the chromatographic column.
The technique is often used to increase sensitivity and minimize
interferences.
    Signal-to-noise ratio (S/N)--The height of the signal as measured
from the mean (average) of the noise to the peak maximum divided by the
width of the noise.
    SIM--See Selection Ion Monitoring.
    Should--This action, activity, or procedural step is suggested but
not required.
    Stock solution--A solution containing an analyte that is prepared
using a reference material traceable to EPA, the National Institute of
Science and Technology (NIST), or a source that will attest to the
purity and authenticity of the reference material.
    Surrogate--A compound unlikely to be found in a sample, and which
is spiked into sample in a known amount before purge-and-trap. The
surrogate is quantitated with the same procedures used to quantitate
the analytes of interest. The purpose of the surrogate is to monitor
method performance with each sample.
* * * * *

Method 625.1--Base/Neutrals and Acids by GC/MS

1. Scope and Application
    1.1 This method is for determination of semivolatile organic
pollutants in industrial discharges and other environmental samples by
gas chromatography combined with mass spectrometry (GC/MS), as provided
under 40 CFR 136.1. This revision is based on a previous protocol
(Reference 1), on the basic revision promulgated October 26, 1984 (49
FR 43234), and on an interlaboratory method validation study (Reference
2). Although this method was validated through an interlaboratory study
conducted more than 29 years ago, the fundamental chemistry principles
used in this method remain sound and continue to apply.
    1.2 The analytes that may be qualitatively and quantitatively
determined using this method and their CAS Registry numbers are listed
in Tables 1 and 2. The method may be extended to determine the analytes
listed in Table 3; however, extraction or gas chromatography of some of
these analytes may make quantitative determination difficult. For
examples, benzidine is subject to oxidative losses during solvent
concentration. Under the alkaline conditions of the extraction, alpha-
BHC, gamma-BHC, endosulfan I and II, and endrin are subject to
decomposition. Hexachlorocyclopentadiene is subject to thermal
decomposition in the inlet of the gas chromatograph, chemical reaction
in acetone solution, and photochemical decomposition. N-
nitrosodiphenylamine and other nitrosoamines may decompose in the gas
chromatographic inlet. EPA has provided other methods (e.g., Method
607--Nitrosamines) for determination of some of these analytes.
    1.3 The large number of analytes in Tables 1-3 of this method makes
testing difficult if all analytes are determined simultaneously.
Therefore, it is necessary to determine and perform quality control
(QC) tests for the ``analytes of interest'' only. Analytes of interest
are those required to be determined by a regulatory/control authority
or in a permit, or by a client. If a list of analytes is not specified,
the analytes in Tables 1 and 2 must be determined, at a minimum, and QC
testing must be performed for these analytes. The analytes in Tables 1
and 2, and some of the analytes in Table 3 have been identified as
Toxic Pollutants (40 CFR 401.15), expanded to a list of Priority
Pollutants (40 CFR part 423, appendix A).
    1.4 In this revision to Method 625, the pesticides and
polychlorinated biphenyls (PCBs) have been moved from Table 1 to Table
3 (Additional Analytes) to distinguish these analytes from the analytes
required in quality control tests (Tables 1 and 2). QC acceptance
criteria for pesticides and PCBs have been retained in Table 6 and may
continue to be applied if desired, or if requested or required by a
regulatory/control authority or in a permit. Method 608 should be used
for determination of pesticides and PCBs. Method 1668C may be useful
for determination of PCBs as individual chlorinated biphenyl congeners,
and Method 1699 may be useful for determination of pesticides. At the
time of writing of this revision, Methods 1668C and 1699 had not been
approved for use at 40 CFR part 136. The screening procedure for
2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) contained in the
version of Method 625 promulgated October 26, 1984 (49 FR 43234) has
been replaced with procedures for selected ion monitoring (SIM), and
2,3,7,8-TCDD may be determined using the SIM procedures. However, EPA
Method 613 or 1613B should be used for analyte-specific determination
of 2,3,7,8-TCDD because of the focus of these methods on this compound.
Methods 613 and 1613B are approved for use at 40 CFR part 136.
    1.5 Method detection limits (MDLs; Reference 3) for the analytes in
Tables 1, 2, and 3 are listed in those tables. These MDLs were
determined in reagent water (Reference 4). Advances in analytical
technology, particularly the use of capillary (open-tubular) columns,
allowed laboratories to routinely achieve MDLs for the analytes in this
method that are 2-10 times lower than those in the version promulgated
in 1984 (40 FR 43234). The MDL for an analyte in a specific wastewater
may differ from those listed, depending upon the nature of
interferences in the sample matrix.
    1.5.1 EPA has promulgated this method at 40 CFR part 136 for use in
wastewater compliance monitoring under the National Pollutant Discharge
Elimination System (NPDES). The data reporting practices described in
Section 15.2 are focused on such monitoring needs and may not be
relevant to other uses of the method.
    1.5.2 This method includes ``reporting limits'' based on EPA's
``minimum level'' (ML) concept (see the glossary in Section 22). Tables
1, 2, and 3 contain MDL values and ML values for many of the analytes.
The MDL for an analyte in a specific wastewater may differ from those
listed in Tables 1, 2, and 3, depending upon the nature of
interferences in the sample matrix.
    1.6 This method is performance-based. It may be modified to improve
performance (e.g., to overcome interferences or improve the accuracy of
results) provided all performance requirements are met.
    1.6.1 Examples of allowed method modifications are described at 40
CFR 136.6. Other examples of allowed modifications specific to this
method are described in Section 8.1.2.

    1.6.2 Any modification beyond those expressly permitted at 40 CFR
136.6 or in Section 8.1.2 of this method shall be considered a major
modification subject to application and approval of an alternate test
procedure under 40 CFR 136.4 and 136.5.
    1.6.3 For regulatory compliance, any modification must be
demonstrated to produce results equivalent or superior to results
produced by this method when applied to relevant wastewaters (Section
8.3).
    1.7 This method is restricted to use by or under the supervision of
analysts experienced in the use of a gas chromatograph/mass
spectrometer and in the interpretation of mass spectra. Each laboratory
that uses this method must demonstrate the ability to generate
acceptable results using the procedure in Section 8.2.
    1.8 Terms and units of measure used in this method are given in the
glossary at the end of the method.
2. Summary of Method
    2.1 A measured volume of sample, sufficient to meet an MDL or
reporting limit, is serially extracted with methylene chloride at pH
11-13 and again at a pH less than 2 using a separatory funnel or
continuous liquid/liquid extractor.
    2.2 The extract is concentrated to a volume necessary to meet the
required compliance or detection limit, and analyzed by GC/MS.
Qualitative identification of an analyte in the extract is performed
using the retention time and the relative abundance of two or more
characteristic masses (m/z's). Quantitative analysis is performed using
the internal standard technique with a single characteristic m/z.
3. Contamination and Interferences
    3.1 Solvents, reagents, glassware, and other sample processing
labware may yield artifacts, elevated baselines, or matrix
interferences causing misinterpretation of chromatograms and mass
spectra. All materials used in the analysis must be demonstrated to be
free from contamination and interferences by analyzing blanks initially
and with each extraction batch (samples started through the extraction
process in a given 12-hour period, to a maximum of 20 samples--see
Glossary for detailed definition), as described in Section 8.5.
Specific selection of reagents and purification of solvents by
distillation in all-glass systems may be required. Where possible,
labware is cleaned by extraction or solvent rinse, or baking in a kiln
or oven.
    3.2 Glassware must be scrupulously cleaned (Reference 5). Clean all
glassware as soon as possible after use by rinsing with the last
solvent used in it. Solvent rinsing should be followed by detergent
washing with hot water, and rinses with tap water and reagent water.
The glassware should then be drained dry, and heated at 400 [deg]C for
15-30 minutes. Some thermally stable materials, such as PCBs, may
require higher temperatures and longer baking times for removal.
Solvent rinses with pesticide quality acetone, hexane, or other
solvents may be substituted for heating. Volumetric labware should not
be heated above 90 [deg]C. After drying and cooling, glassware should
be sealed and stored in a clean environment to prevent any accumulation
of dust or other contaminants. Store inverted or capped with solvent-
rinsed or baked aluminum foil.
    3.3 Matrix interferences may be caused by contaminants co-extracted
from the sample. The extent of matrix interferences will vary
considerably from source to source, depending upon the nature and
diversity of the industrial complex or municipality being sampled.
Interferences extracted from samples high in total organic carbon (TOC)
may result in elevated baselines, or by enhancing or suppressing a
signal at or near the retention time of an analyte of interest.
Analyses of the matrix spike and duplicate (Section 8.3) may be useful
in identifying matrix interferences, and gel permeation chromatography
(GPC; Section 11.1) and sulfur removal (Section 11.2) may aid in
eliminating these interferences. EPA has provided guidance that may aid
in overcoming matrix interferences (Reference 6).
    3.4 In samples that contain an inordinate number of interferences,
the use of chemical ionization (CI) mass spectrometry may make
identification easier. Tables 4 and 5 give characteristic CI m/z's for
many of the analytes covered by this method. The use of CI mass
spectrometry to support electron ionization (EI) mass spectrometry is
encouraged, but not required.
4. Safety
    4.1 Hazards associated with each reagent used in this method have
not been precisely defined; however, each chemical compound should be
treated as a potential health hazard. From this viewpoint, exposure to
these chemicals must be reduced to the lowest possible level by
whatever means available. The laboratory is responsible for maintaining
a current awareness file of OSHA regulations regarding the safe
handling of the chemicals specified in this method. A reference file of
safety data sheets (SDSs, OSHA, 29 CFR 1910.1200(g)) should also be
made available to all personnel involved in sample handling and
chemical analysis. Additional references to laboratory safety are
available and have been identified (References 7-9) for the information
of the analyst.
    4.2 The following analytes covered by this method have been
tentatively classified as known or suspected human or mammalian
carcinogens: benzo(a)anthracene, benzidine, 3,3'-dichlorobenzidine,
benzo(a)pyrene, alpha-BHC, beta-BHC, delta-BHC, gamma-BHC, Dibenz(a,h)-
anthracene, N-nitrosodimethylamine, 4,4'-DDT, and PCBs. Other compounds
in Table 3 may also be toxic. Primary standards of toxic compounds
should be prepared in a chemical fume hood, and a NIOSH/MESA approved
toxic gas respirator should be worn when handling high concentrations
of these compounds.
    4.3 This method allows the use of hydrogen as a carrier gas in
place of helium (Section <IP_ADDRESS>). The laboratory should take the
necessary precautions in dealing with hydrogen, and should limit
hydrogen flow at the source to prevent buildup of an explosive mixture
of hydrogen in air.
5. Apparatus and Materials

    Note:  Brand names, suppliers, and part numbers are for
illustration purposes only. No endorsement is implied. Equivalent
performance may be achieved using equipment and materials other than
those specified here. Demonstrating that the equipment and supplies
used in the laboratory achieves the required performance is the
responsibility of the laboratory. Suppliers for equipment and
materials in this method may be found through an on-line search.
Please do not contact EPA for supplier information.

    5.1 Sampling equipment, for discrete or composite sampling.
    5.1.1 Grab sample bottle--amber glass bottle large enough to
contain the necessary sample volume, fitted with a fluoropolymer-lined
screw cap. Foil may be substituted for fluoropolymer if the sample is
not corrosive. If amber bottles are not available, protect samples from
light. Unless pre-cleaned, the bottle and cap liner must be washed,
rinsed with acetone or methylene chloride, and dried before use to
minimize contamination.
    5.1.2 Automatic sampler (optional)--the sampler must incorporate a
pre-cleaned glass sample container. Samples must be kept refrigerated
at <6 [deg]C and protected from light during compositing. If the
sampler uses a peristaltic pump, a minimum length of compressible
silicone rubber tubing may be used. Before use,

however, the compressible tubing should be thoroughly rinsed with
methanol, followed by repeated rinsings with reagent water to minimize
the potential for contamination of the sample. An integrating flow
meter is required to collect flow-proportioned composites.
    5.2 Glassware.
    5.2.1 Separatory funnel--Size appropriate to hold sample volume and
extraction solvent volume, and equipped with fluoropolymer stopcock.
    5.2.2 Drying column--Chromatographic column, approximately 400 mm
long by 19 mm ID, with coarse frit, or equivalent, sufficient to hold
15 g of anhydrous sodium sulfate.
    5.2.3 Concentrator tube, Kuderna-Danish--10 mL, graduated (Kontes
570050-1025 or equivalent). Calibration must be checked at the volumes
employed in the test. A ground glass stopper is used to prevent
evaporation of extracts.
    5.2.4 Evaporative flask, Kuderna-Danish--500 mL (Kontes 57001-0500
or equivalent). Attach to concentrator tube with springs.

    Note:  Use of a solvent recovery system with the K-D or other
solvent evaporation apparatus is strongly recommended.

    5.2.5 Snyder column, Kuderna-Danish--Three ball macro (Kontes
503000-0121 or equivalent).
    5.2.6 Snyder column, Kuderna-Danish--Two-ball micro (Kontes 569001-
0219 or equivalent).
    5.2.7 Vials--10-15 mL, amber glass, with Teflon-lined screw cap.
    5.2.8 Continuous liquid-liquid extractor--Equipped with
fluoropolymer or glass connecting joints and stopcocks requiring no
lubrication. (Hershberg-Wolf Extractor, Ace Glass Company, Vineland,
N.J., P/N 6848-20, or equivalent.)
    5.2.9 In addition to the glassware listed above, the laboratory
should be equipped with all necessary pipets, volumetric flasks,
beakers, and other glassware listed in this method and necessary to
perform analyses successfully.
    5.3 Boiling chips--Approximately 10/40 mesh, glass, silicon
carbide, or equivalent. Heat to 400 [deg]C for 30 minutes, or solvent
rinse or Soxhlet extract with methylene chloride.
    5.4 Water bath--Heated, with concentric ring cover, capable of
temperature control (2 [deg]C). The bath should be used in
a hood.
    5.5 Balances.
    5.5.1 Analytical, capable of accurately weighing 0.1 mg.
    5.5.2 Top loading, capable of accurately weighing 10 mg.
    5.6 GC/MS system.
    5.6.1 Gas chromatograph (GC)--An analytical system complete with a
temperature programmable gas chromatograph and all required
accessories, including syringes and analytical columns.
    <IP_ADDRESS> Injection port--Can be split, splitless, temperature
programmable split/splitless (PTV), solvent-purge, large-volume, on-
column, backflushed, or other. An autosampler is highly recommended
because it injects volumes more precisely than volumes injected
manually.
    <IP_ADDRESS> Carrier gas--Helium or hydrogen. Data in the tables in this
method were obtained using helium carrier gas. If hydrogen is used,
analytical conditions may need to be adjusted for optimum performance,
and calibration and all QC tests must be performed with hydrogen
carrier gas. See Section 4.3 for precautions regarding the use of
hydrogen as a carrier gas.
    5.6.2 GC column--See the footnotes to Tables 4 and 5. Other columns
or column systems may be used provided all requirements in this method
are met.
    5.6.3 Mass spectrometer--Capable of repetitively scanning from 35-
450 Daltons (amu) every two seconds or less, utilizing a 70 eV
(nominal) electron energy in the electron impact ionization mode, and
producing a mass spectrum which meets all the criteria in Table 9A or
9B when 50 ng or less of decafluorotriphenyl phosphine (DFTPP; CAS
5074-71-5; bis(pentafluorophenyl) phenyl phosphine) is injected into
the GC.
    5.6.4 GC/MS interface--Any GC to MS interface that meets all
performance requirements in this method may be used.
    5.6.5 Data system--A computer system must be interfaced to the mass
spectrometer that allows the continuous acquisition and storage of mass
spectra acquired throughout the chromatographic program. The computer
must have software that allows searching any GC/MS data file for
specific m/z's (masses) and plotting m/z abundances versus time or scan
number. This type of plot is defined as an extracted ion current
profile (EICP). Software must also be available that allows integrating
the abundance at any EICP between specified time or scan number limits.
    5.7 Automated gel permeation chromatograph (GPC).
    5.7.1 GPC column--150--700 mm long x 21-25 mm ID, packed with 70 g
of SX-3 Biobeads; Bio-Rad Labs, or equivalent
    5.7.2 Pump, injection valve, UV detector, and other apparatus
necessary to meet the requirements in this method.
    5.8 Nitrogen evaporation device--Equipped with a water bath than
can be maintained at 30-45 [deg]C; N-Evap, Organomation Associates, or
equivalent.
6. Reagents
    6.1 Reagent water--Reagent water is defined as water in which the
analytes of interest and interfering compounds are not detected at the
MDLs of the analytes of interest.
    6.2 Sodium hydroxide solution (10 N)--Dissolve 40 g of NaOH (ACS)
in reagent water and dilute to 100 mL.
    6.3 Sodium thiosulfate--(ACS) granular.
    6.4 Sulfuric acid (1+1)--Slowly add 50 mL of
H2SO4 (ACS, sp. gr. 1.84) to 50 mL of reagent
water.
    6.5 Acetone, methanol, methylene chloride, 2-propanol--High purity
pesticide quality, or equivalent, demonstrated to be free of the
analytes of interest and interferences (Section 3). Purification of
solvents by distillation in all-glass systems may be required.
    6.6 Sodium sulfate--(ACS) granular, anhydrous, rinsed or Soxhlet
extracted with methylene chloride (20 mL/g), baked at in a shallow tray
at 450 [deg]C for one hour minimum, cooled in a desiccator, and stored
in a pre-cleaned glass bottle with screw cap that prevents moisture
from entering.
    6.7 Stock standard solutions (1.00 [mu]g/[mu]L)--Stock standard
solutions may be prepared from pure materials, or purchased as
certified solutions. Traceability must be to the National Institute of
Standards and Technology (NIST) or other national standard, when
available. Stock solution concentrations alternate to those below may
be used. Because of the toxicity of some of the compounds, primary
dilutions should be prepared in a hood, and a NIOSH/MESA approved toxic
gas respirator should be worn when high concentrations of neat
materials are handled. The following procedure may be used to prepare
standards from neat materials.
    6.7.1 Prepare stock standard solutions by accurately weighing about
0.0100 g of pure material. Dissolve the material in pesticide quality
methanol or other suitable solvent and dilute to volume in a 10 mL
volumetric flask. Larger volumes may be used at the convenience of the
laboratory. When compound purity is assayed to be 96% or greater, the
weight may be used without correction to calculate the concentration of
the stock standard. Commercially prepared stock standards

may be used at any concentration if they are certified by the
manufacturer or by an independent source.
    6.7.2 Transfer the stock standard solutions to fluoropolymer-sealed
screw-cap bottles. Store at <6 [deg]C and protect from light. Stock
standard solutions should be checked frequently for signs of
degradation or evaporation, especially just prior to preparing
calibration standards from them.
    6.7.3 Replace purchased certified stock standard solutions per the
expiration date. Replace stock standard solutions prepared by the
laboratory or mixed with purchased solutions after one year, or sooner
if comparison with QC check samples indicates a problem.
    6.8 Surrogate standard spiking solution
    6.8.1 Select a minimum of three surrogate compounds from Table 8
that most closely match the recovery of the analytes of interest. For
example, if all analytes tested are considered acids, use surrogates
that have similar chemical attributes. Other compounds may be used as
surrogates so long as they do not interfere in the analysis. The
deuterium and carbon-13 labeled compounds in Method 1625B are
particularly useful because Method 1625B contains QC acceptance
criteria for recovery of these compounds. If only one or two analytes
are determined, one or two surrogates may be used.
    6.8.2 Prepare a solution containing each selected surrogate such
that the concentration in the sample would match the concentration in
the mid-point calibration standard. For example, if the midpoint of the
calibration is 100 [mu]g/L, prepare the spiking solution at a
concentration of 100 [mu]g/mL in methanol. Addition of 1.00 mL of this
solution to 1000 mL of sample will produce a concentration of 100
[mu]g/L of the surrogate. Alternate volumes and concentrations
appropriate to the response of the GC/MS instrument or for selective
ion monitoring (SIM) may be used, if desired.
    6.8.3 Store the spiking solution at <= 6[deg]C in a fluoropolymer-
sealed glass container. The solution should be checked frequently for
stability. The solution must be replaced after one year, or sooner if
comparison with quality control check standards indicates a problem.
    6.9 Internal standard spiking solution
    6.9.1 Select three or more internal standards similar in
chromatographic behavior to the analytes of interest. Internal
standards are listed in Table 8. Suggested internal standards are: 1,4-
dichlorobenzene-d4; naphthalene-d8; acenaphthene-
d10; phenanthrene-d10; chrysene-d12;
and perylene-d12. The laboratory must demonstrate that
measurement of the internal standards is not affected by method or
matrix interferences (see also Section 7.3.4).
    6.9.2 Prepare the internal standards at a concentration of 10 mg/mL
in methylene chloride or other suitable solvent. When 10 [mu]L of this
solution is spiked into a 1-mL extract, the concentration of the
internal standards will be 100 [mu]g/mL. A lower concentration
appropriate to the response of the GC/MS instrument or for SIM may be
used, if desired.
    6.9.3 To assure accurate analyte identification, particularly when
SIM is used, it may be advantageous to include more internal standards
than those suggested in Section 6.9.1. An analyte will be located most
accurately if its retention time relative to an internal standard is in
the range of 0.8 to 1.2.
    6.10 DFTPP standard--Prepare a solution of DFTPP in methanol or
other suitable solvent such that 50 ng or less will be injected (see
Section 13.2). An alternate concentration may be used to compensate for
specific injection volumes or to assure that the operating range of the
instrument is not exceeded, so long as the total injected is 50 ng or
less. Include benzidine and pentachlorophenol in this solution such
that <=100 ng of benzidine and <=50 ng of pentachlorophenol will be
injected.
    6.11 Quality control check sample concentrate--See Section 8.2.1.
    6.12 GPC calibration solution
    6.12.1 Prepare a methylene chloride solution to contain corn oil,
bis(2-ethylhexyl) phthalate (BEHP), perylene, and sulfur at the
concentrations in Section 6.12.2, or at concentrations appropriate to
the response of the detector.

    Note: Sulfur does not readily dissolve in methylene chloride,
but is soluble in warm corn oil. The following procedure is
suggested for preparation of the solution:

    6.12.2 Weigh 8 mg sulfur and 2.5 g corn oil into a 100-mL
volumetric flask and warm to dissolve the sulfur. Separately weigh 100
mg BEHP and 2 mg perylene and add to flask. Bring to volume with
methylene chloride and mix thoroughly.
    6.12.3 Store the solution in an amber glass bottle with a
fluoropolymer-lined screw cap at 0-6 [deg]C. Protect from light.
Refrigeration may cause the corn oil to precipitate. Before use, allow
the solution to stand at room temperature until the corn oil dissolves,
or warm slightly to aid in dissolution. Replace the solution every
year, or more frequently if the response of a component changes.
    6.13 Sulfur removal--Copper foil or powder (bright, non-oxidized),
or tetrabutylammonium sulfite (TBA sulfite).
    6.13.1 Copper foil, or powder--Fisher, Alfa Aesar 42455-18, 625
mesh, or equivalent. Cut copper foil into approximately 1-cm squares.
Copper must be activated on each day it will be used, as follows:
    <IP_ADDRESS> Place the quantity of copper needed for sulfur removal
(Section <IP_ADDRESS>) in a ground-glass-stoppered Erlenmeyer flask or
bottle. Cover the foil or powder with methanol.
    <IP_ADDRESS> Add HCl dropwise (0.5-1.0 mL) while swirling, until the
copper brightens.
    <IP_ADDRESS> Pour off the methanol/HCl and rinse 3 times with reagent
water to remove all traces of acid, then 3 times with acetone, then 3
times with hexane.
    <IP_ADDRESS> For copper foil, cover with hexane after the final rinse.
Store in a stoppered flask under nitrogen until used. For the powder,
dry on a rotary evaporator or under a stream of nitrogen. Store in a
stoppered flask under nitrogen until used.
    6.13.2 Tetrabutylammonium sodium sulfite (TBA sodium sulfite).
    <IP_ADDRESS> Tetrabutylammonium hydrogen sulfate,
[CH3(CH2)3]4NHSO4
.
    <IP_ADDRESS> Sodium sulfite, Na2SO3.
    <IP_ADDRESS> Dissolve approximately 3 g tetrabutylammonium hydrogen
sulfate in 100 mL of reagent water in an amber bottle with
fluoropolymer-lined screw cap. Extract with three 20-mL portions of
hexane and discard the hexane extracts.
    <IP_ADDRESS> Add 25 g sodium sulfite to produce a saturated solution.
Store at room temperature. Replace after 1 month.
7. Calibration
    7.1 Establish operating conditions equivalent to those in the
footnote to Table 4 or 5 for the base/neutral or acid fraction,
respectively. If a combined base/neutral/acid fraction will be
analyzed, use the conditions in the footnote to Table 4. Alternative
temperature program and flow rate conditions may be used. It is
necessary to calibrate the GC/MS for the analytes of interest (Section
1.3) only.
    7.2 Internal standard calibration
    7.2.1 Prepare calibration standards for the analytes of interest
and surrogates at a minimum of five concentration levels by adding
appropriate volumes of one or more stock standards to volumetric
flasks. One of the calibration standards should be at a concentration
near the ML for the analyte in Table 1, 2, or 3. The ML value may be
rounded to a whole number that

is more convenient for preparing the standard, but must not exceed the
ML values listed in Table 1, 2, or 3 for those analytes which list ML
values. Alternatively, the laboratory may establish the ML for each
analyte based on the concentration of the lowest calibration standard
in a series of standards obtained from a commercial vendor, again,
provided that the ML values do not exceed the MLs in Tables 1, 2, or 3,
and provided that the resulting calibration meets the acceptance
criteria in Section 7.2.3, based on the RSD, RSE, or R\2\.
    The other concentrations should correspond to the expected range of
concentrations found in real samples or should define the working range
of the GC/MS system for full-scan and/or SIM operation, as appropriate.
A minimum of six concentration levels is required for a second order,
non-linear (e.g., quadratic; ax\2\ + bx + c) calibration. Calibrations
higher than second order are not allowed. To each calibration standard
or standard mixture, add a known constant volume of the internal
standard solution (Section 6.9), and dilute to volume with methylene
chloride.

    Note: The large number of analytes in Tables 1 through 3 may not
be soluble or stable in a single solution; multiple solutions may be
required if a large number of analytes are to be determined
simultaneously.

    <IP_ADDRESS> Prior to analysis of the calibration standards, inject the
DFTPP standard (Section 6.10) and adjust the scan rate of the mass
spectrometer to produce a minimum of 5 mass spectra across the DFTPP GC
peak. Adjust instrument conditions until the DFTPP criteria in Table 9A
or 9B are met. Calculate peak tailing factors for benzidine and
pentachlorophenol. Calculation of the tailing factor is illustrated in
Figure 1. The tailing factor for benzidine and pentachlorophenol must
be <2; otherwise, adjust instrument conditions and either replace the
column or break off a short section of the front end of the column, and
repeat the test.

    Note: The DFTPP spectrum may be evaluated by summing the
intensities of the m/z's across the GC peak, subtracting the
background at each m/z in a region of the chromatogram within 20
scans of but not including any part of, the DFTPP peak. The DFTPP
spectrum may also be evaluated by fitting a Gaussian to each m/z and
using the intensity at the maximum for each Gaussian or by
integrating the area at each m/z and using the integrated areas.
Other means may be used for evaluation of the DFTPP spectrum so long
as the spectrum is not distorted to meet the criteria in Table 9A or
9B.

    <IP_ADDRESS> Analyze the mid-point combined base/neutral and acid
calibration standard and enter or review the retention time, relative
retention time, mass spectrum, and quantitation m/z in the data system
for each analyte of interest, surrogate, and internal standard. If
additional analytes (Table 3) are to be quantified, include these
analytes in the standard. The mass spectrum for each analyte must be
comprised of a minimum of 2 m/z's (Tables 4 and 5); 3 to 5 m/z's assure
more reliable analyte identification. Suggested quantitation m/z's are
shown in Tables 4 and 5 as the primary m/z. If an interference occurs
at the primary m/z, use one of the secondary m/z's or an alternate m/z.
A single m/z only is required for quantitation.
    <IP_ADDRESS> For SIM operation, determine the analytes in each
descriptor, the quantitation and qualifier m/z's for each analyte (the
m/z's can be the same as for full-scan operation; Section <IP_ADDRESS>), the
dwell time on each m/z for each analyte, and the beginning and ending
retention time for each descriptor. Analyze the verification standard
in scan mode to verify m/z's and establish the retention times for the
analytes. There must be a minimum of two m/z's for each analyte to
assure analyte identification. To maintain sensitivity and capture
enough scans (>=5) across each chromatographic peak, there should be no
more than 10 m/z's in a descriptor. For example, for a descriptor with
10 m/z's and a chromatographic peak width of 5 sec, a dwell time of 100
ms at each m/z would result in a scan time of 1 second and provide 5
scans across the GC peak. The quantitation m/z will usually be the most
intense peak in the mass spectrum. The quantitation m/z and dwell time
may be optimized for each analyte. However, if a GC peak spans two (or
more) descriptors, the dwell time and cycle time (scans/sec) should be
set to the same value in both segments in order to maintain equivalent
response. The acquisition table used for SIM must take into account the
mass defect (usually less than 0.2 Daltons) that can occur at each m/z
being monitored.
    <IP_ADDRESS> For combined scan and SIM operation, set up the scan
segments and descriptors to meet requirements in Sections <IP_ADDRESS>-
<IP_ADDRESS>.
    7.2.2 Analyze each calibration standard according to Section 12 and
tabulate the area at the quantitation m/z against concentration for
each analyte of interest, surrogate, and internal standard. If an
interference is encountered, use a secondary m/z (Table 4 or 5) for
quantitation. Calculate a response factor (RF) for each analyte of
interest at each concentration using Equation 1.
[GRAPHIC] [TIFF OMITTED] TP19FE15.016

Where:

As = Area of the characteristic m/z for the analyte of
interest or surrogate.
Ais = Area of the characteristic m/z for the internal
standard.
Cis = Concentration of the internal standard ([mu]g/mL).
Cs = Concentration of the analyte of interest or
surrogate ([mu]g/mL).

    7.2.3 Calculate the mean (average) and relative standard deviation
(RSD) of the responses factors. If the RSD is less than 35%, the RF can
be assumed to be invariant and the average RF can be used for
calculations. Alternatively, the results can be used to fit a linear or
quadratic regression of response ratios, As/Ais, vs. concentration
ratios Cs/Cis. If used, the regression must be weighted inversely
proportional to concentration. The coefficient of determination (R\2\;
Reference 10) of the weighted regression must be greater than 0.920.
Alternatively, the relative standard error (Reference 11) may be used
as an acceptance criterion. As with the RSD, the RSE must be less than
35%. If an RSE less than 35% cannot be achieved for a quadratic
regression, system performance is unacceptable and the system must be
adjusted and re-calibrated.

    Note: Using capillary columns and current instrumentation, it is
quite likely that a laboratory can calibrate the target analytes in
this method and achieve a linearity metric (either RSD or RSE) well
below 35%. Therefore, laboratories are permitted to use more
stringent acceptance criteria for calibration than described here,
for example, to harmonize their application of this method with
those from other sources.

    7.3 Calibration verification--The RF or calibration curve must be
verified immediately after calibration and at the beginning of each 12-
hour shift, by analysis of a mid-point calibration standard (Section
7.2.1). The standard(s)

must be obtained from a second manufacturer or a manufacturer's batch
prepared independently from the batch used for calibration.
Traceability must be to a national standard, when available. The
concentration of the standard should be near the mid-point of the
calibration. Include the surrogates (Section 6.8) in this solution. It
is necessary to verify calibration for the analytes of interest
(Section 1.3) only.

    Note: The 12-hour shift begins after the DFTPP (Section 13.1)
and DDT/endrin tests (if DDT and endrin are to be determined), and
after analysis of the calibration verification standard. The 12-hour
shift ends 12 hours later. The DFTPP and DDT/endrin tests are
outside of the 12-hour shift.

    7.3.1 Analyze the calibration verification standard(s) beginning in
Section 12. Calculate the percent recovery of each analyte. Compare the
recoveries for the analytes of interest against the acceptance criteria
for recovery (Q) in Table 6, and the recoveries for the surrogates
against the acceptance criteria in Table 8. If recovery of the analytes
of interest and surrogates meet acceptance criteria, system performance
is acceptable and analysis of samples may continue. If any individual
recovery is outside its limit, system performance is unacceptable for
that analyte.

    Note: The large number of analytes in Tables 6 and 8 present a
substantial probability that one or more will fail acceptance
criteria when all analytes are tested simultaneously.

    7.3.2 When one or more analytes fail acceptance criteria, analyze a
second aliquot of the calibration verification standard and compare
only those analytes that failed the first test (Section 7.3.1) with
their respective acceptance criteria. If these analytes now pass,
system performance is acceptable and analysis of samples may continue.
A repeat failure of any analyte that failed the first test, however,
will confirm a general problem with the measurement system. If this
occurs, repair the system (Section <IP_ADDRESS>) and repeat the test
(Section 7.3.1), or prepare a fresh calibration standard and repeat the
test. If calibration cannot be verified after maintenance or injection
of the fresh calibration standard, re-calibrate the instrument.

    Note: If it is necessary to perform a repeat verification test
frequently; i.e., perform two tests in order to pass, it may be
prudent to perform two injections in succession and review the
results, rather than perform one injection, review the results, then
perform the second injection if results from the first injection
fail. To maintain the validity of the test and re-test, system
maintenance and/or adjustment is not permitted between the
injections.

    7.3.3 Many of the analytes in Table 3 do not have QC acceptance
criteria in Table 6, and some of the surrogates in Table 8 do not have
acceptance criteria. If calibration is to be verified and other QC
tests are to be performed for these analytes, acceptance criteria must
be developed and applied. EPA has provided guidance for development of
QC acceptance criteria (References 12 and 13).
    7.3.4 Internal standard responses--Verify that detector sensitivity
has not changed by comparing the response of each internal standard in
the calibration verification standard (Section 7.3) to the response of
the respective internal standard in the midpoint calibration standard
(Section 7.2.1). The peak areas or heights of the internal standards in
the calibration verification standard must be within 50% to 200% (\1/2\
to 2x) of their respective peak areas or heights in the mid-point
calibration standard. If not, repeat the calibration verification test
using a fresh calibration verification standard (7.3), or perform and
document system repair. Subsequent to repair, repeat the calibration
verification test (Section 7.3.1). If the responses are still not
within 50% to 200%, re-calibrate the instrument (Section 7.2.2) and
repeat the calibration verification test.
8. Quality Control
    8.1 Each laboratory that uses this method is required to operate a
formal quality assurance program. The minimum requirements of this
program consist of an initial demonstration of laboratory capability
and ongoing analysis of spiked samples and blanks to evaluate and
document data quality (40 CFR 136.7). The laboratory must maintain
records to document the quality of data generated. Results of ongoing
performance tests are compared with established QC acceptance criteria
to determine if the results of analyses meet performance requirements
of this method. When results of spiked samples do not meet the QC
acceptance criteria in this method, a quality control check sample
(laboratory control sample; LCS) must be analyzed to confirm that the
measurements were performed in an in-control mode of operation. A
laboratory may develop its own performance criteria (as QC acceptance
criteria), provided such criteria are as or more restrictive than the
criteria in this method.
    8.1.1 The laboratory must make an initial demonstration of
capability (DOC) to generate acceptable precision and recovery with
this method. This demonstration is detailed in Section 8.2.
    8.1.2 In recognition of advances that are occurring in analytical
technology, and to overcome matrix interferences, the laboratory is
permitted certain options (Section 1.6 and 40 CFR 136.6(b)) to improve
separations or lower the costs of measurements. These options may
include alternate extraction, concentration, and cleanup procedures
(e.g., solid-phase extraction; rotary-evaporator concentration; column
chromatography cleanup), changes in column and type of mass
spectrometer (40 CFR 136.6(b)(4)(xvi)). Alternate determinative
techniques, such as substitution of spectroscopic or immunoassay
techniques, and changes that degrade method performance, are not
allowed. If an analytical technique other than GC/MS is used, that
technique must have a specificity equal to or greater than the
specificity of GC/MS for the analytes of interest. The laboratory is
also encouraged to participate in inter-comparison and performance
evaluation studies (see Section 8.10).
    <IP_ADDRESS> Each time a modification is made to this method, the
laboratory is required to repeat the procedure in Section 8.2. If the
detection limit of the method will be affected by the change, the
laboratory must demonstrate that the MDLs (40 CFR part 136, appendix B)
are lower than one-third the regulatory compliance limit or the MDLs in
this method, whichever are greater. If calibration will be affected by
the change, the instrument must be recalibrated per Section 7. Once the
modification is demonstrated to produce results equivalent or superior
to results produced by this method, that modification may be used
routinely thereafter, so long as the other requirements in this method
are met (e.g., matrix spike/matrix spike duplicate recovery and
relative percent difference).
    <IP_ADDRESS>.1 If SPE, or another allowed method modification, is to be
applied to a specific discharge, the laboratory must prepare and
analyze matrix spike/matrix spike duplicate (MS/MSD) samples (Section
8.3) and LCS samples (Section 8.4). The laboratory must include
surrogates (Section 8.7) in each of the samples. The MS/MSD and LCS
samples must be fortified with the analytes of interest (Section 1.3).
If the modification is for nationwide use, MS/MSD samples must be
prepared from a minimum of nine different discharges (See Section
<IP_ADDRESS>.2), and all QC acceptance criteria in this method must be met.
This evaluation only needs to be performed once other than for the
routine QC required by this method (for example it could be performed
by the

vendor of the SPE materials) but any laboratory using that specific SPE
material must have the results of the study available. This includes a
full data package with the raw data that will allow an independent
reviewer to verify each determination and calculation performed by the
laboratory (see Section <IP_ADDRESS>.5, items a-q).
    <IP_ADDRESS>.2 Sample matrices on which MS/MSD tests must be performed
for nationwide use of an allowed modification:
    (a) Effluent from a POTW.
    (b) ASTM D5905 Standard Specification for Substitute Wastewater.
    (c) Sewage sludge, if sewage sludge will be in the permit.
    (d) ASTM D1141 Standard Specification for Substitute Ocean Water,
if ocean water will be in the permit.
    (e) Untreated and treated wastewaters up to a total of nine matrix
types (see http://water.epa.gov/scitech/wastetech/guide/industry.cfm)
for a list of industrial categories with existing effluent guidelines).
    At least one of the above wastewater matrix types must have at
least one of the following characteristics:
    (i) Total suspended solids greater than 40 mg/L.
    (ii) Total dissolved solids greater than 100 mg/L.
    (iii) Oil and grease greater than 20 mg/L.
    (iv) NaCl greater than 120 mg/L.
    (v) CaCO3 greater than 140 mg/L.
    The interim acceptance criteria for MS, MSD recoveries that do not
have recovery limits specified in Table 6, and recoveries for
surrogates that do not have recovery limits specified in Table 8, must
be no wider than 60-140%, and the relative percent difference (RPD) of
the concentrations in the MS and MSD that do not have RPD limits
specified in Table 6 must be less than 30%. Alternatively, the
laboratory may use the laboratory's in-house limits if they are
tighter.
    (f) A proficiency testing (PT) sample from a recognized provider,
in addition to tests of the nine matrices (Section <IP_ADDRESS>.1).
    <IP_ADDRESS> The laboratory is required to maintain records of
modifications made to this method. These records include the following,
at a minimum:
    <IP_ADDRESS>.1 The names, titles, street addresses, telephone numbers,
and email addresses of the analyst(s) that performed the analyses and
modification, and of the quality control officer that witnessed and
will verify the analyses and modifications.
    <IP_ADDRESS>.2 A list of analytes, by name and CAS Registry Number.
    <IP_ADDRESS>.3 A narrative stating reason(s) for the modifications.
    <IP_ADDRESS>.4 Results from all quality control (QC) tests comparing the
modified method to this method, including:
    (a) Calibration (Section 7).
    (b) Calibration verification (Section 7).
    (c) Initial demonstration of capability (Section 8.2).
    (d) Analysis of blanks (Section 8.5).
    (e) Matrix spike/matrix spike duplicate analysis (Section 8.3).
    (f) Laboratory control sample analysis (Section 8.4).
    <IP_ADDRESS>.5 Data that will allow an independent reviewer to validate
each determination by tracing the instrument output (peak height, area,
or other signal) to the final result. These data are to include:
    (a) Sample numbers and other identifiers.
    (b) Extraction dates.
    (c) Analysis dates and times.
    (d) Analysis sequence/run chronology.
    (e) Sample weight or volume (Section 10).
    (f) Extract volume prior to each cleanup step (Sections 10 and 11).
    (g) Extract volume after each cleanup step (Section 11).
    (h) Final extract volume prior to injection (Sections 10 and 12).
    (i) Injection volume (Section 12.2.3).
    (j) Sample or extract dilution (Section <IP_ADDRESS>).
    (k) Instrument and operating conditions.
    (l) Column (dimensions, material, etc).
    (m) Operating conditions (temperature program, flow rate, etc).
    (n) Detector (type, operating conditions, etc).
    (o) Chromatograms, mass spectra, and other recordings of raw data.
    (p) Quantitation reports, data system outputs, and other data to
link the raw data to the results reported.
    (q) A written Standard Operating Procedure (SOP).
    <IP_ADDRESS>.6 Each individual laboratory wishing to use a given
modification must perform the start-up tests in Section 8.1.2 (e.g.,
DOC, MDL), with the modification as an integral part of this method
prior to applying the modification to specific discharges. Results of
the DOC must meet the QC acceptance criteria in Table 6 for the
analytes of interest (Section 1.3), and the MDLs must be equal to or
lower than the MDLs in Tables 4 and 5 for the analytes of interest.
    8.1.3 Before analyzing samples, the laboratory must analyze a blank
to demonstrate that interferences from the analytical system, labware,
and reagents, are under control. Each time a batch of samples is
extracted or reagents are changed, a blank must be extracted and
analyzed as a safeguard against laboratory contamination. Requirements
for the blank are given in Section 8.5.
    8.1.4 The laboratory must, on an ongoing basis, spike and analyze a
minimum of one sample, in duplicate, with the samples in an extraction
batch (Section 3.1). The laboratory must also spike and analyze, in
duplicate, a minimum of 5% of all samples from a given site or
discharge to monitor and evaluate method and laboratory performance on
the sample matrix. The batch and site/discharge samples may be the
same. The procedure for spiking and analysis is given in Section 8.3.
    8.1.5 The laboratory must, on an ongoing basis, demonstrate through
analysis of a quality control check sample (laboratory control sample,
LCS; on-going precision and recovery sample, OPR) that the measurement
system is in control. This procedure is given in Section 8.4.
    8.1.6 The laboratory should maintain performance records to
document the quality of data that is generated. This procedure is given
in Section 8.9.
    8.1.7 The large number of analytes tested in performance tests in
this method present a substantial probability that one or more will
fail acceptance criteria when many analytes are tested simultaneously,
and a re-test is allowed if this situation should occur. If, however,
continued re-testing results in further repeated failures, the
laboratory should document the failures (e.g., as qualifiers on
results) and either avoid reporting results for analytes that failed or
report the problem and failures with the data. Failure to report does
not relieve a discharger or permittee of reporting timely results.
    8.2 Initial demonstration of capability (DOC)--To establish the
ability to generate acceptable recovery and precision, the laboratory
must perform the DOC in Sections 8.2.1 through 8.2.6 for the analytes
of interest. The laboratory must also establish MDLs for the analytes
of interest using the MDL procedure at 40 CFR part 136, appendix B. The
laboratory's MDLs must be equal to or lower than those listed in Tables
1, 2, or 3 or lower than one third the regulatory compliance limit,
whichever is greater. For MDLs not listed in Tables 4 and 5, the
laboratory must determine the MDLs using the MDL procedure at 40 CFR
136, Appendix B under the same conditions used to determine the MDLs
for the analytes listed in Tables 1, 2, and 3. All

procedures used in the analysis, including cleanup procedures, must be
included in the DOC.
    8.2.1 For the DOC, a QC check sample concentrate containing each
analyte of interest (Section 1.3) is prepared in a water-miscible
solvent. The QC check sample concentrate must be prepared independently
from those used for calibration, but may be from the same source as the
second-source standard used for calibration verification (Section 7.3).
The concentrate should produce concentrations of the analytes of
interest in water at the mid-point of the calibration range, and may be
at the same concentration as the LCS (Section 8.4). Multiple solutions
may be required.

    Note:  QC check sample concentrates are no longer available from
EPA.

    8.2.2 Using a pipet or micro-syringe, prepare four LCSs by adding
an appropriate volume of the concentrate to each of four 1-L aliquots
of reagent water, and mix well. The volume of reagent water must be the
same as the volume that will be used for the sample, blank (Section
8.5), and MS/MSD (Section 8.3). A concentration of 100 [mu]g/L was used
to develop the QC acceptance criteria in Table 6. Also add an aliquot
of the surrogate spiking solution (Section 6.8). Also add an aliquot of
the surrogate spiking solution (Section 6.8) to the reagent-water
aliquots.
    8.2.3 Extract and analyze the four LCSs according to the method
beginning in Section 10.
    8.2.4 Calculate the average percent recovery (x) and the standard
deviation of the percent recovery(s) for each analyte using the four
results.
    8.2.5 For each analyte, compare s and (x) with the corresponding
acceptance criteria for precision and recovery in Table 6. For analytes
in Table 3 not listed in Table 6, DOC QC acceptance criteria must be
developed by the laboratory. EPA has provided guidance for development
of QC acceptance criteria (References 12 and 13). If s and (x) for all
analytes of interest meet the acceptance criteria, system performance
is acceptable and analysis of blanks and samples may begin. If any
individual s exceeds the precision limit or any individual (x) falls
outside the range for recovery, system performance is unacceptable for
that analyte.

    Note:  The large number of analytes in Tables 1-3 present a
substantial probability that one or more will fail at least one of
the acceptance criteria when many or all analytes are determined
simultaneously. Therefore, the analyst is permitted to conduct a
``re-test'' as described in Sec. 8.2.6.

    8.2.6 When one or more of the analytes tested fail at least one of
the acceptance criteria, repeat the test for only the analytes that
failed. If results for these analytes pass, system performance is
acceptable and analysis of samples and blanks may proceed. If one or
more of the analytes again fail, system performance is unacceptable for
the analytes that failed the acceptance criteria. Correct the problem
and repeat the test (Section 8.2). See Section 8.1.7 for disposition of
repeated failures.

    Note:  To maintain the validity of the test and re-test, system
maintenance and/or adjustment is not permitted between this pair of
tests.

    8.3 Matrix spike and matrix spike duplicate (MS/MSD)--The
laboratory must, on an ongoing basis, spike at least 5% of the samples
from each sample site being monitored in duplicate to assess accuracy
(recovery and precision). The data user should identify the sample and
the analytes of interest (Section 1.3) to be spiked. If direction
cannot be obtained, the laboratory must spike at least one sample per
extraction batch of up to 20 samples with the analytes in Tables 1 and
2. Spiked sample results should be reported only to the data user whose
sample was spiked, or as requested or required by a regulatory/control
authority.
    8.3.1 If, as in compliance monitoring, the concentration of a
specific analyte will be checked against a regulatory concentration
limit, the concentration of the spike should be at that limit;
otherwise, the concentration of the spike should be one to five times
higher than the background concentration determined in Section 8.3.2,
at or near the midpoint of the calibration range, or at the
concentration in the LCS (Section 8.4) whichever concentration would be
larger.
    8.3.2 Analyze one sample aliquot to determine the background
concentration (B) of the each analyte of interest. If necessary,
prepare a new check sample concentrate (Section 8.2.1) appropriate for
the background concentration. Spike and analyze two additional sample
aliquots, and determine the concentration after spiking (A1
and A2) of each analyte. Calculate the percent recoveries
(P1 and P2) as 100 (A1-B)/T and 100
(A2-B)/T, where T is the known true value of the spike. Also
calculate the relative percent difference (RPD) between the
concentrations (A1 and A2) as
200[verbarlm]A1-A2[verbarlm]/(A1 +
A2). If necessary, adjust the concentrations used to
calculate the RPD to account for differences in the volumes of the
spiked aliquots.
    8.3.3 Compare the percent recoveries (P1 and
P2) and the RPD for each analyte in the MS/MSD aliquots with
the corresponding QC acceptance criteria in Table 6. A laboratory may
develop and apply QC acceptance criteria more restrictive than the
criteria in Table 6, if desired.
    <IP_ADDRESS> If any individual P falls outside the designated range for
recovery in either aliquot, or the RPD limit is exceeded, the result
for the analyte in the unspiked sample is suspect and may not be
reported or used for permitting or regulatory compliance purposes. See
Section 8.1.7 for disposition of failures.
    <IP_ADDRESS> The acceptance criteria in Table 6 were calculated to
include an allowance for error in measurement of both the background
and spike concentrations, assuming a spike to background ratio of 5:1.
This error will be accounted for to the extent that the spike to
background ratio approaches 5:1 (Reference 14). If spiking is performed
at a concentration lower than 100 [mu]g/L, the laboratory must use
either the QC acceptance criteria in Table 6, or optional QC acceptance
criteria calculated for the specific spike concentration. To use the
optional acceptance criteria: (1) Calculate recovery (X') using the
equation in Table 7, substituting the spike concentration (T) for C;
(2) Calculate overall precision (S') using the equation in Table 7,
substituting X' for x; (3) Calculate the range for recovery at the
spike concentration as (100 X'/T)  2.44(100 S'/T)%
(Reference 14). For analytes in Table 3 not listed in Table 6, QC
acceptance criteria must be developed by the laboratory. EPA has
provided guidance for development of QC acceptance criteria (References
12 and 13).
    8.3.4 After analysis of a minimum of 20 MS/MSD samples for each
target analyte and surrogate, the laboratory must calculate and apply
in-house QC limits for recovery and RPD of future MS/MSD samples
(Section 8.3). The QC limits for recovery are calculated as the mean
observed recovery  3 standard deviations, and the upper QC
limit for RPD is calculated as the mean RPD plus 3 standard deviations
of the RPDs. The in-house QC limits must be updated at least every two
years and re-established after any major change in the analytical
instrumentation or process. At least 80% of the analytes tested in the
MS/MSD must have in-house QC acceptance criteria that are tighter than
those in Table 6. If an in-house QC limit for the RPD is greater than
the limit in Table 6,

then the limit in Table 6 must be used. Similarly, if an in-house lower
limit for recovery is below the lower limit in Table 6, then the lower
limit in Table 6 must be used, and if an in-house upper limit for
recovery is above the upper limit in Table 6, then the upper limit in
Table 6 must be used. The laboratory must evaluate surrogate recovery
data in each sample against its in-house surrogate recovery limits. The
laboratory may use 60-140% as interim acceptance criteria for surrogate
recoveries until in-house limits are developed.
    8.4 Laboratory control sample (LCS)--A QC check sample (laboratory
control sample, LCS; on-going precision and recovery sample, OPR)
containing each analyte of interest (Section 1.3) and surrogate must be
prepared and analyzed with each extraction batch of up to 20 samples to
demonstrate acceptable recovery of the analytes of interest from a
clean sample matrix.
    8.4.1 Prepare the LCS by adding QC check sample concentrate
(Section 8.2.1) to reagent water. Include all analytes of interest
(Section 1.3) in the LCS. The LCS may be the same sample prepared for
the DOC (Section 8.2.1). The volume of reagent water must be the same
as the volume used for the sample, blank (Section 8.5), and MS/MSD
(Section 8.3). Also add an aliquot of the surrogate spiking solution
(Section 6.8). The concentration of the analytes in reagent water
should be the same as the concentration in the DOC (Section 8.2.2).
    8.4.2 Analyze the LCS prior to analysis of field samples in the
extraction batch. Determine the concentration (A) of each analyte.
Calculate the percent recovery (PS) as 100 (A/T)%, where T is the true
value of the concentration in the LCS.
    8.4.3 Compare the percent recovery (PS) for each analyte with its
corresponding QC acceptance criterion in Table 6. For analytes of
interest in Table 3 not listed in Table 6, use the QC acceptance
criteria developed for the MS/MSD (Section <IP_ADDRESS>). If the recoveries
for all analytes of interest fall within their respective QC acceptance
criteria, analysis of blanks and field samples may proceed. If any
individual PS falls outside the range, proceed according to Section
8.4.4.

    Note:  The large number of analytes in Tables 1-3 present a
substantial probability that one or more will fail the acceptance
criteria when all analytes are tested simultaneously. Because a re-
test is allowed in event of failure (Sections 8.1.7 and 8.4.3), it
may be prudent to extract and analyze two LCSs together and evaluate
results of the second analysis against the QC acceptance criteria
only if an analyte fails the first test.

    8.4.4 Repeat the test only for those analytes that failed to meet
the acceptance criteria (PS). If these analytes now pass, system
performance is acceptable and analysis of blanks and samples may
proceed. Repeated failure, however, will confirm a general problem with
the measurement system. If this occurs, repeat the test using a fresh
LCS (Section 8.2.2) or an LCS prepared with a fresh QC check sample
concentrate (Section 8.2.1), or perform and document system repair.
Subsequent to repair, repeat the LCS test (Section 8.4). If failure of
the LCS indicates a systemic problem with samples in the batch, re-
extract and re-analyze the samples in the batch. See Section 8.1.7 for
disposition of repeated failures.

    Note:  To maintain the validity of the test and re-test, system
maintenance and/or adjustment is not permitted between the pair of
tests.

    8.4.5 After analysis of 20 LCS samples, the laboratory must
calculate and apply in-house QC limits for recovery to future LCS
samples (Section 8.4). Limits for recovery in the LCS are calculated as
the mean recovery 3 standard deviations. A minimum of 80%
of the analytes tested for in the LCS must have QC acceptance criteria
tighter than those in Table 6. Many of the analytes and surrogates may
not contain recommended acceptance criteria. The laboratory should use
60-140% as interim acceptance criteria for recoveries of spiked
analytes and surrogates that do not have recovery limits specified in
Table 8, until in-house LCS and surrogate limits are developed. If an
in-house lower limit for recovery is lower than the lower limit in
Table 6, the lower limit in Table 6 must be used, and if an in-house
upper limit for recovery is higher than the upper limit in Table 6, the
upper limit in Table 6 must be used.
    8.5 Blank--A blank must be extracted and analyzed with each
extraction batch to demonstrate that the reagents and equipment used
for preparation and analysis are free from contamination.
    8.5.1 Spike the surrogates into the blank. Extract and concentrate
the blank using the same procedures and reagents used for the samples,
LCS, and MS/MSD in the batch. Analyze the blank immediately after
analysis of the LCS (Section 8.4) and prior to analysis of the MS/MSD
and samples to demonstrate freedom from contamination.
    8.5.2 If any analyte of interest is found in the blank: 1) At a
concentration greater than the MDL for the analyte, 2) at a
concentration greater than one-third the regulatory compliance limit,
or 3) at a concentration greater than one-tenth the concentration in a
sample in the extraction batch, whichever is greater, analysis of
samples must be halted and samples affected by the blank must be re-
extracted and the extracts re-analyzed. Samples must be associated with
an uncontaminated blank before they may be reported or used for
permitting or regulatory compliance purposes.
    8.6 Internal standards responses.
    8.6.1 Calibration verification--The responses (GC peak heights or
areas) of the internal standards in the calibration verification must
be within 50% to 200% (\1/2\ to 2x) of their respective responses in
the mid-point calibration standard. If they are not, repeat the
calibration verification (Section 7.4) test or perform and document
system repair. Subsequent to repair, repeat the calibration
verification. If the responses are still not within 50% to 200%, re-
calibrate the instrument (Section 7) and repeat the calibration
verification/LCS test.
    8.6.2 Samples, blanks, LCSs, and MS/MSDs--The responses (GC peak
heights or areas) of the internal standards in each sample, blank, and
MS/MSD must be within 50% to 200% (\1/2\ to 2x) of its respective
response in the most recent LCS. If, as a group, all internal standards
are not within this range, perform and document system repair, repeat
the calibration verification/LCS test (Section 8.4), and re-analyze the
affected samples. If a single internal standard is not within the 50%
to 200% range, use an alternate internal standard for quantitation of
the analyte referenced to the affected internal standard.
    8.7 Surrogate recoveries--Spike the surrogates into all samples,
blanks, LCSs, and MS/MSDs. Compare surrogate recoveries against the QC
acceptance criteria in Table 8 and/or those developed in Section 7.3.3.
If any recovery fails its criteria, attempt to find and correct the
cause of the failure. Surrogate recoveries from the blank and LCS may
be used as pass/fail criteria by the laboratory or as required by a
regulatory authority, or may be used to diagnose problems with the
analytical system.
    8.8 DDT and endrin decomposition (breakdown)--If DDT and/or endrin
are to be analyzed using this method, a DDT/endrin decomposition test
must be performed to reliably quantify these two pesticides. The DDT/
endrin decomposition test to be used is in EPA Method 608A or 1656.

    8.9 As part of the QC program for the laboratory, control charts or
statements of accuracy for wastewater samples must be assessed and
records maintained (40 CFR 136.7(c)(1)(viii)). After analysis of five
or more spiked wastewater samples as in Section 8.3, calculate the
average percent recovery (x) and the standard deviation of the percent
recovery (sp). Express the accuracy assessment as a percent interval
from x -2sp to x +2sp. For example, if x = 90% and sp = 10%, the
accuracy interval is expressed as 70-110%. Update the accuracy
assessment for each analyte on a regular basis (e.g., after each 5-10
new accuracy measurements).
    8.10 It is recommended that the laboratory adopt additional quality
assurance practices for use with this method. The specific practices
that are most productive depend upon the needs of the laboratory and
the nature of the samples. Field duplicates may be analyzed to assess
the precision of environmental measurements. Whenever possible, the
laboratory should analyze standard reference materials and participate
in relevant performance evaluation studies.
9. Sample Collection, Preservation, and Handling
    9.1 Collect samples as grab samples in glass bottles or in
refrigerated bottles using automatic sampling equipment. Collect 1-L of
ambient waters, effluents, and other aqueous samples. If the
sensitivity of the analytical system is sufficient, a smaller volume
(e.g., 250 mL), but no less than 100 mL, may be used. Conventional
sampling practices (Reference 15) should be followed, except that the
bottle must not be pre-rinsed with sample before collection. Automatic
sampling equipment must be as free as possible of polyvinyl chloride or
other tubing or other potential sources of contamination. If needed,
collect additional sample(s) for the MS/MSD (Section 8.3).
    9.2 Ice or refrigerate samples at <=6 [deg]C from the time of
collection until extraction, but do not freeze. If residual chlorine is
present, add 80 mg of sodium thiosulfate per liter of sample and mix
well. Any method suitable for field use may be employed to test for
residual chlorine (Reference 16). Do not add excess sodium thiosulfate.
If sodium thiosulfate interferes in the determination of the analytes,
an alternate preservative (e.g., ascorbic acid or sodium sulfite) may
be used.
    9.3 All samples must be extracted within 7 days of collection and
sample extracts must be analyzed within 40 days of extraction.
10. Extraction
    10.1 This section contains procedures for separatory funnel liquid-
liquid extraction (SFLLE) and continuous liquid-liquid extraction
(CLLE). SFLLE is faster, but may not be as effective as CLLE for
recovery of polar analytes such as phenol. SFLLE is labor intensive and
may result in formation of emulsions that are difficult to break. CLLE
is less labor intensive, avoids emulsion formation, but requires more
time (18-24 hours) and more hood space, and may require more solvent.
The procedures assume base-neutral extraction followed by acid
extraction. For some matrices and analytes of interest, improved
results may be obtained by acid-neutral extraction followed by base
extraction. A single acid or base extraction may also be performed. If
an extraction scheme alternate to base-neutral followed by acid
extraction is used, all QC tests must be performed and all QC
acceptance criteria must be met with that extraction scheme as an
integral part of this method.
    10.2 Separatory funnel liquid-liquid extraction (SFLLE) and extract
concentration
    10.2.1 The SFLLE procedure below assumes a sample volume of 1 L.
When a different sample volume is extracted, adjust the volume of
methylene chloride accordingly.
    10.2.2 Mark the water meniscus on the side of the sample bottle for
later determination of sample volume. Pour the entire sample into the
separatory funnel. Pipet the surrogate standard spiking solution
(Section 6.8) into the separatory funnel. If the sample will be used
for the LCS or MS or MSD, pipet the appropriate check sample
concentrate (Section 8.2.1 or 8.3.2) into the separatory funnel. Mix
well. Check the pH of the sample with wide-range pH paper and adjust to
pH 11-13 with sodium hydroxide solution.
    10.2.3 Add 60 mL of methylene chloride to the sample bottle, seal,
and shake for approximately 30 seconds to rinse the inner surface.
Transfer the solvent to the separatory funnel and extract the sample by
shaking the funnel for two minutes with periodic venting to release
excess pressure. Allow the organic layer to separate from the water
phase for a minimum of 10 minutes. If the emulsion interface between
layers is more than one-third the volume of the solvent layer, the
analyst must employ mechanical techniques to complete the phase
separation. The optimum technique depends upon the sample, but may
include stirring, filtration of the emulsion through glass wool,
centrifugation, or other physical methods. Collect the methylene
chloride extract in a flask. If the emulsion cannot be broken (recovery
of <80% of the methylene chloride), transfer the sample, solvent, and
emulsion into a continuous extractor and proceed as described in
Section 10.3.
    10.2.4 Add a second 60-mL volume of methylene chloride to the
sample bottle and repeat the extraction procedure a second time,
combining the extracts in the Erlenmeyer flask. Perform a third
extraction in the same manner.
    10.2.5 Adjust the pH of the aqueous phase to less than 2 using
sulfuric acid. Serially extract the acidified aqueous phase three times
with 60 mL aliquots of methylene chloride. Collect and combine the
extracts in a flask in the same manner as the base/neutral extracts.

    Note:  Base/neutral and acid extracts may be combined for
concentration and analysis provided all QC tests are performed and
all QC acceptance criteria met for the analytes of interest with the
combined extract as an integral part of this method, and provided
that the analytes of interest are as reliably identified and
quantified as when the extracts are analyzed separately. If doubt
exists as to whether identification and quantitation will be
affected by use of a combined extract, the fractions must be
analyzed separately.

    10.2.6 For each fraction or the combined fractions, assemble a
Kuderna-Danish (K-D) concentrator by attaching a 10-mL concentrator
tube to a 500-mL evaporative flask. Other concentration devices or
techniques may be used in place of the K-D concentrator so long as the
requirements in Section 8.2 are met.
    10.2.7 For each fraction or the combined fractions, pour the
extract through a solvent-rinsed drying column containing about 10 cm
of anhydrous sodium sulfate, and collect the extract in the K-D
concentrator. Rinse the Erlenmeyer flask and column with 20-30 mL of
methylene chloride to complete the quantitative transfer.
    10.2.8 Add one or two clean boiling chips and attach a three-ball
Snyder column to the evaporative flask for each fraction (Section
10.2.7). Pre-wet the Snyder column by adding about 1 mL of methylene
chloride to the top. Place the K-D apparatus on a hot water bath (60-65
[deg]C) so that the concentrator tube is partially immersed in the hot
water, and the entire lower rounded surface of the flask is bathed with
hot vapor. Adjust the vertical position of the apparatus and the water
temperature as required to complete the concentration in 15-20 minutes.
At the proper rate of

distillation, the balls of the column will actively chatter but the
chambers will not flood with condensed solvent. When the apparent
volume of liquid reaches 1 mL or other determined amount, remove the K-
D apparatus from the water bath and allow to drain and cool for at
least 10 minutes. Remove the Snyder column and rinse the flask and its
lower joint into the concentrator tube with 1-2 mL of methylene
chloride. A 5-mL syringe is recommended for this operation. If the
sample will be cleaned up, reserve the K-D apparatus for concentration
of the cleaned up extract. Adjust the volume to 5 mL with methylene
chloride and proceed to Section 11 for cleanup; otherwise, further
concentrate the extract for GC/MS analysis per Section 10.2.9 or
10.2.10.
    10.2.9 Micro Kuderna-Danish concentration--add another one or two
clean boiling chips to the concentrator tube for each fraction and
attach a two-ball micro-Snyder column. Pre-wet the Snyder column by
adding about 0.5 mL of methylene chloride to the top. Place the K-D
apparatus on a hot water bath (60-65 [deg]C) so that the concentrator
tube is partially immersed in hot water. Adjust the vertical position
of the apparatus and the water temperature as required to complete the
concentration in 5-10 minutes. At the proper rate of distillation the
balls of the column will actively chatter but the chambers will not
flood with condensed solvent. When the apparent volume of liquid
reaches about 1 mL or other determined amount, remove the K-D apparatus
from the water bath and allow it to drain and cool for at least 10
minutes. Remove the Snyder column and rinse the flask and its lower
joint into the concentrator tube with approximately 0.2 mL of or
methylene chloride. Adjust the final volume to 1.0 mL or a volume
appropriate to the sensitivity desired (e.g., to meet lower MDLs or for
selected ion monitoring). Record the volume, stopper the concentrator
tube and store refrigerated if further processing will not be performed
immediately. If the extracts will be stored longer than two days, they
should be transferred to fluoropolymer-lined screw-cap vials and
labeled base/neutral or acid fraction as appropriate. Mark the level of
the extract on the vial so that solvent loss can be detected.
    10.2.10 Nitrogen evaporation and solvent exchange--Extracts may be
concentrated for analysis using nitrogen evaporation in place of micro
K-D concentration (Section 10.2.9). Extracts that have been cleaned up
using sulfur removal (Section 12.2) and are ready for analysis are
exchanged into methylene chloride.
    <IP_ADDRESS> Transfer the vial containing the sample extract to the
nitrogen evaporation (blowdown) device (Section 5.8). Lower the vial
into the water bath and begin concentrating. If the more volatile
analytes (Section 1.2) are to be concentrated, use room temperature for
concentration; otherwise, a slightly elevated (e.g., 30-45 [deg]C) may
be used. During the solvent evaporation process, keep the solvent level
below the water level of the bath and do not allow the extract to
become dry. Adjust the flow of nitrogen so that the surface of the
solvent is just visibly disturbed. A large vortex in the solvent may
cause analyte loss.
    <IP_ADDRESS> Extracts to be solvent exchanged--When the volume of the
liquid is approximately 200 [mu]L, add 2 to 3 mL of methylene chloride
and continue concentrating to approximately 100 [mu]L. Repeat the
addition of solvent and concentrate once more. Adjust the final extract
volume to be consistent with the volume extracted and the sensitivity
desired.
    <IP_ADDRESS> For extracts that have been cleaned up by GPC and that
are to be concentrated to a nominal volume of 1 mL, adjust the final
volume to compensate the GPC loss. For a 50% GPC loss, concentrate the
extract to 1/2000 of the volume extracted. For example, if the volume
extracted is 950 mL, adjust the final volume to 0.48 mL. For extracts
that have not been cleaned up by GPC and are to be concentrated to a
nominal volume of 1.0 mL, adjust the final extract volume to 1/1000 of
the volume extracted. For example, if the volume extracted is 950 mL,
adjust the final extract volume to 0.95 mL.

    Note: The difference in the volume fraction for an extract
cleaned up by GPC accounts for the loss in GPC cleanup. Also, by
preserving the ratio between the volume extracted and the final
extract volume, the concentrations and detection limits do not need
to be adjusted for differences in the volume extracted and the
extract volume.

    10.2.11 Transfer the concentrated extract to a vial with
fluoropolymer-lined cap. Seal the vial and label with the sample
number. Store in the dark at room temperature until ready for GC
analysis. If GC analysis will not be performed on the same day, store
the vial in the dark at <=6 [deg]C. Analyze the extract by GC/MS per
the procedure in Section 12.
    10.2.12 Determine the original sample volume by refilling the
sample bottle to the mark and transferring the liquid to an
appropriately sized graduated cylinder. For sample volumes on the order
of 1000 mL, record the sample volume to the nearest 10 mL; for sample
volumes on the order of 100 mL, record the volume to the nearest 1 mL.
Sample volumes may also be determined by weighing the container before
and after filling to the mark with water.
    10.3 Continuous liquid/liquid extraction (CLLE).

    Note:  With CLLE, phenol, 2,4-dimethyl phenol, and some other
analytes may be preferentially extracted into the base-neutral
fraction. Determine an analyte in the fraction in which it is
identified and quantified most reliably. Also, the short-chain
phthalate esters (e.g., dimethyl phthalate, diethyl phthalate) and
some other compounds may hydrolyze during prolonged exposure to
basic conditions required for continuous extraction, resulting in
low recovery of these analytes. When these analytes are of interest,
their recovery may be improved by performing the acid extraction
first.

    10.3.1 Use CLLE when experience with a sample from a given source
indicates an emulsion problem, or when an emulsion is encountered
during SFLLE. CLLE may be used for all samples, if desired.
    10.3.2 Mark the water meniscus on the side of the sample bottle for
later determination of sample volume. Check the pH of the sample with
wide-range pH paper and adjust to pH 11-13 with sodium hydroxide
solution. Transfer the sample to the continuous extractor. Pipet
surrogate standard spiking solution (Section 6.8) into the sample. If
the sample will be used for the LCS or MS or MSD, pipet the appropriate
check sample concentrate (Section 8.2.1 or 8.3.2) into the extractor.
Mix well. Add 60 mL of methylene chloride to the sample bottle, seal,
and shake for 30 seconds to rinse the inner surface. Transfer the
solvent to the extractor.
    10.3.3 Repeat the sample bottle rinse with an additional 50-100 mL
portion of methylene chloride and add the rinse to the extractor.
    10.3.4 Add a suitable volume of methylene chloride to the
distilling flask (generally 200-500 mL), add sufficient reagent water
to ensure proper operation, and extract for 18-24 hours. A shorter or
longer extraction time may be used if all QC acceptance criteria are
met. Test and, if necessary, adjust the pH of the water during the
second or third hour of the extraction. After extraction, allow the
apparatus to cool, then detach the distilling flask. Dry, concentrate,
and seal the extract per Sections 10.2.6 through 10.2.11. See the note
at Section 10.2.5 regarding combining extracts of the base/neutral and
acid fractions.
    10.3.5 Charge the distilling flask with methylene chloride and
attach it to the continuous extractor. Carefully,

while stirring, adjust the pH of the aqueous phase to less than 2 using
sulfuric acid. Extract for 18-24 hours. A shorter or longer extraction
time may be used if all QC acceptance criteria are met. Test and, if
necessary, adjust the pH of the water during the second or third hour
of the extraction. After extraction, allow the apparatus to cool, then
detach the distilling flask. Dry, concentrate, and seal the extract per
Sections 10.2.6 through 10.2.11. Determine the sample volume per
Section 10.2.12.
11. Extract Cleanup

    Note:  Cleanup may not be necessary for relatively clean samples
(e.g., treated effluents, groundwater, drinking water). If
particular circumstances require the use of a cleanup procedure, the
laboratory may use any or all of the procedures below or any other
appropriate procedure. Before using a cleanup procedure, the
laboratory must demonstrate that the requirements of Section 8.1.2
can be met using the cleanup procedure as an integral part of this
method.

    11.1 Gel permeation chromatography (GPC).
    11.1.1 Calibration.
    <IP_ADDRESS> Load the calibration solution (Section 6.12) into the
sample loop.
    <IP_ADDRESS> Inject the calibration solution and record the signal from
the detector. The elution pattern will be corn oil, bis(2-ethylhexyl)
phthalate, pentachlorophenol, perylene, and sulfur.
    <IP_ADDRESS> Set the ``dump time'' to allow >85% removal of the corn
oil and >85% collection of the phthalate.
    <IP_ADDRESS> Set the ``collect time'' to the peak minimum between
perylene and sulfur.
    <IP_ADDRESS> Verify calibration with the calibration solution after
every 20 or fewer extracts. Calibration is verified if the recovery of
the pentachlorophenol is greater than 85%. If calibration is not
verified, recalibrate using the calibration solution, and re-extract
and clean up the preceding extracts using the calibrated GPC system.
    11.1.2 Extract cleanup--GPC requires that the column not be
overloaded. The column specified in this method is designed to handle a
maximum of 0.5 g of high molecular weight material in a 5-mL extract.
If the extract is known or expected to contain more than 0.5 g, the
extract is split into fractions for GPC and the fractions are combined
after elution from the column. The solids content of the extract may be
obtained gravimetrically by evaporating the solvent from a 50-[mu]L
aliquot.
    <IP_ADDRESS> Filter the extract or load through the filter holder to
remove particulates. Load the extract into the sample loop. The maximum
capacity of the column is 0.5-1.0 g. If necessary, split the extract
into multiple aliquots to prevent column overload.
    <IP_ADDRESS> Elute the extract using the calibration data determined in
Section 11.1.1. Collect the eluate in the K-D apparatus reserved in
Section 10.2.8.
    11.1.3 Concentrate the cleaned up extract per Sections 10.2.8 and
10.2.9 or 10.2.10.
    11.1.4 Rinse the sample loading tube thoroughly with methylene
chloride between extracts to prepare for the next sample.
    11.1.5 If a particularly dirty extract is encountered, run a
methylene chloride blank through the system to check for carry-over.
    11.2 Sulfur removal.

    Note:  Separate procedures using copper or TBA sulfite are
provided in this section for sulfur removal. They may be used
separately or in combination, if desired.

    11.2.1 Removal with copper (Reference 17).

    Note:  If (1) an additional compound (Table 3) is to be
determined; (2) sulfur is to be removed; (3) copper will be used for
sulfur removal; and (4) a sulfur matrix is known or suspected to be
present, the laboratory must demonstrate that the additional
compound can be successfully extracted and treated with copper in
the sulfur matrix. Some of the additional compounds (Table 3) are
known not to be amenable to sulfur removal with copper (e.g.
Atrazine and Diazinon).

    <IP_ADDRESS> Quantitatively transfer the extract from Section 10.2.8 to
a 40- to 50-mL flask or bottle. If there is evidence of water in the
concentrator tube after the transfer, rinse the tube with small
portions of hexane:acetone (40:60) and add to the flask or bottle. Mark
and set aside the concentrator tube for use in re-concentrating the
extract.
    <IP_ADDRESS> Add 10-20 g of granular anhydrous sodium sulfate to the
flask. Swirl to dry the extract.
    <IP_ADDRESS> Add activated copper (Section <IP_ADDRESS>) and allow to stand
for 30-60 minutes, swirling occasionally. If the copper does not remain
bright, add more and swirl occasionally for another 30-60 minutes.
    <IP_ADDRESS> After drying and sulfur removal, quantitatively transfer
the extract to a nitrogen-evaporation vial or tube and proceed to
Section 10.2.10 for nitrogen evaporation and solvent exchange, taking
care to leave the sodium sulfate and copper in the flask.
    11.2.2 Removal with TBA sulfite.
    <IP_ADDRESS> Using small volumes of hexane, quantitatively transfer the
extract to a 40- to 50-mL centrifuge tube with fluoropolymer-lined
screw cap.
    <IP_ADDRESS> Add 1-2 mL of TBA sulfite reagent (Section <IP_ADDRESS>), 2-3
mL of 2-propanol, and approximately 0.7 g of sodium sulfite (Section
<IP_ADDRESS>) crystals to the tube. Cap and shake for 1-2 minutes. If the
sample is colorless or if the initial color is unchanged, and if clear
crystals (precipitated sodium sulfite) are observed, sufficient sodium
sulfite is present. If the precipitated sodium sulfite disappears, add
more crystalline sodium sulfite in approximately 0.5 g portions until a
solid residue remains after repeated shaking.
    <IP_ADDRESS> Add 5-10 mL of reagent water and shake for 1-2 minutes.
Centrifuge to settle the solids.
    <IP_ADDRESS> Quantitatively transfer the hexane (top) layer through a
small funnel containing a few grams of granular anhydrous sodium
sulfate to a nitrogen-evaporation vial or tube and proceed to Section
10.2.10 for nitrogen evaporation and solvent exchange.
12. Gas Chromatography/Mass Spectrometry
    12.1 Establish the operating conditions in Table 4 or 5 for
analysis of a base/neutral or acid extract, respectively. For analysis
of a combined extract (Section 10.2.5, note), use the operating
conditions in Table 4. Included in these tables are retention times and
MDLs that can be achieved under these conditions. Examples of the
separations achieved are shown in Figure 2 for the combined extract.
Alternative columns or chromatographic conditions may be used if the
requirements of Section 8.2 are met. Verify system performance per
Section 13.
    12.2 Analysis of a standard or extract.
    12.2.1 Bring the standard or concentrated extract (Section 10.2.9
or 10.2.11) to room temperature and verify that any precipitate has
redissolved. Verify the level on the extract and bring to the mark with
solvent if required.
    12.2.2 Add the internal standard solution (Section 6.9) to the
extract. Mix thoroughly.
    12.2.3 Inject an appropriate volume of the sample extract or
standard solution using split, splitless, solvent purge, large-volume,
or on-column injection. If the sample is injected manually the solvent-
flush technique should be used. The injection volume depends upon the
technique used and the ability to meet MDLs or reporting limits for
regulatory compliance. Injected volumes must be the same for standards
and sample extracts. Record the volume injected to two significant
figures.

    <IP_ADDRESS> Start the GC column oven program upon injection. Start MS
data collection after the solvent peak elutes. Stop data collection
after benzo(ghi)perylene elutes for the base/neutral or combined
fractions, or after pentachlorophenol elutes for the acid fraction.
Return the column to the initial temperature for analysis of the next
standard solution or extract.
    <IP_ADDRESS> If the concentration of any analyte of interest exceeds
the calibration range, either extract and analyze a smaller sample
volume, or dilute and analyze the diluted extract after bringing the
concentrations of the internal standards to the levels in the undiluted
extract.
    12.2.4 Perform all qualitative and quantitative measurements as
described in Sections 14 and 15. When standards and extracts are not
being used for analyses, store them refrigerated at <=6 [deg]C
protected from light in screw-cap vials equipped with un-pierced
fluoropolymer-lined septa.
13. Performance tests
    13.1 At the beginning of each 12-hour shift during which standards
or extracts will be analyzed, perform the tests in Sections 13.2-13.7
to verify system performance. If DDT and/or endrin are to be
determined, perform the decomposition test in Section 13.8. If an
extract is concentrated for greater sensitivity (e.g., by SIM), all
tests must be performed at levels consistent with the reduced extract
volume.
    13.2 DFTPP--Inject the DFTPP standard (Section 6.10) and verify
that the criteria for DFTPP in Section <IP_ADDRESS> and Table 9A (Reference
18) for a quadrupole MS, or Table 9B (Reference 19) for a time-of-
flight MS, are met. It is not necessary to meet DFTPP criteria for SIM
operation.
    13.3 GC resolution--There must be a valley between
benzo(b)fluoranthene and benzo(k)fluoranthene at m/z 252, and the
height of the valley must not exceed 25 percent of the shorter of the
two peaks.
    13.4 Calibration verification--Verify calibration per Sections 7.3
and Table 6.
    13.5 Peak tailing--Verify the tailing factor specifications are met
per Section <IP_ADDRESS>.
    13.6 Laboratory control sample and blank--Analyze the extracts of
the LCS and blank at the beginning of analyses of samples in the
extraction batch (Section 3.1). The LCS must meet the requirements in
Section 8.4, and the blank must meet the requirements in Section 8.5
before sample extracts may be analyzed.
    13.7 Matrix spike/matrix spike duplicate--Analyze the background
sample for the MS/MSD and the MS and MSD after the blank (Section
8.3.2). Results for the MS/MSD must meet the requirements in Section
8.3 before a result for an analyte in any unspiked sample in the batch
may be reported or used for permitting or regulatory compliance
purposes.
    13.8 DDT/endrin decomposition test--If DDT and/or endrin analytes
of interest, the DDT/endrin test (Section 8.8) must be performed and
the QC acceptance criteria must be met before analyzing samples for DDT
and/or endrin.
14. Qualitative Identification
    14.1 Identification is accomplished by comparison of data from
analysis of a sample or blank with data stored in the GC/MS data system
(Sections 5.6.5 and <IP_ADDRESS>, and Tables 4 and 5). Identification of an
analyte is confirmed per Sections 14.1.1 through 14.1.4.
    14.1.1 The signals for all characteristic m/z's stored in the data
system for each analyte of interest must be present and must maximize
within the same two consecutive scans.
    14.1.2 Based on the relative retention time (RRT), the RRT for the
analyte must be within 0.06 of the RRT of the analyte in
the calibration verification run at the beginning of the shift (Section
7.3 or 13.4). Relative retention time is used to establish the
identification window because it compensates for small changes in the
GC temperature program whereas the absolute retention time does not
(see Section 6.9.3).

    Note:  RRT is a unitless quantity (see Sec. 20.2), although some
procedures refer to ``RRT units'' in providing the specification for
the agreement between the RRT values in the sample and the
calibration verification or other standard.

    14.1.3 Either (1) the background corrected EICP areas, or (2) the
corrected relative intensities of the mass spectral peaks at the GC
peak maximum, must agree within 50% to 200% (\1/2\ to 2 times) for all
m/z's in the reference mass spectrum stored in the data system (Section
<IP_ADDRESS>), or from a reference library. For example, if a peak has an
intensity of 20% relative to the base peak, the analyte is identified
if the intensity of the peak in the sample is in the range of 10% to
40% of the base peak.
    14.1.4 The m/z's present in the acquired mass spectrum for the
sample that are not present in the reference mass spectrum must be
accounted for by contaminant or background m/z's. A reference library
may be helpful to identify and account for background or contaminant m/
z's. If the acquired mass spectrum is contaminated, or if
identification is ambiguous, an experienced spectrometrist (Section
1.7) must determine the presence or absence of the compound.
    14.2 Structural isomers that have very similar mass spectra can be
identified only if the resolution between authentic isomers in a
standard mix is acceptable. Acceptable resolution is achieved if the
baseline to valley height between the isomers is less than 50% of the
height of the shorter of the two peaks. Otherwise, structural isomers
are identified as isomeric pairs.
15. Calculations
    15.1 When an analyte has been identified, quantitation of that
analyte is based on the integrated abundance from the EICP of the
primary characteristic m/z in Table 4 or 5. Calculate the concentration
in the extract using the response factor (RF) determined in Section
7.2.2 and Equation 2. If the concentration of an analyte exceeds the
calibration range, dilute the extract by the minimum amount to bring
the concentration into the calibration range, and re-analyze the
extract. Determine a dilution factor (DF) from the amount of the
dilution. For example, if the extract is diluted by a factor of 2, DF =
2.
[GRAPHIC] [TIFF OMITTED] TP19FE15.017

Where:

Cex = Concentration of the analyte in the extract, in
[micro]g/mL, and the other terms are as defined in Equation 1.

    Calculate the concentration of the analyte in the sample using the
concentration in the extract, the extract volume, the sample volume,
and the dilution factor, per Equation 3:

[GRAPHIC] [TIFF OMITTED] TP19FE15.018

Where:

Cs = Concentration of the analyte in the sample
Cex = Concentration of the analyte in the extract, in
[mu]g/mL
Vex = Volume of extract (mL)
Vs = Volume of sample (L)
DF = Dilution factor

    15.2 Reporting of results
    As noted in Section 1.4.1, EPA has promulgated this method at 40
CFR part 136 for use in wastewater compliance monitoring under the
National Pollutant Discharge Elimination System (NPDES). The data
reporting practices described here are focused on such monitoring needs
and may not be relevant to other uses of the method.
    15.2.1 Report results for wastewater samples in [mu]g/L without
correction for recovery. (Other units may be used if required by in a
permit.) Report all QC data with the sample results.
    15.2.2 Reporting level
    Unless otherwise specified in by a regulatory authority or in a
discharge permit, results for analytes that meet the identification
criteria are reported down to the concentration of the ML established
by the laboratory through calibration of the instrument (see Section
7.3.2 and the glossary for the derivation of the ML). EPA considers the
terms ``reporting limit,'' ``quantitation limit,'' and ``minimum
level'' to be synonymous.
    <IP_ADDRESS> Report a result for each analyte in each sample, blank, or
standard at or above the ML to 3 significant figures. Report a result
for each analyte found in each sample below the ML as ``ML,'' or as
required by the regulatory authority or permit. Results are reported
without blank subtraction unless requested or required by a regulatory
authority or in a permit. In this case, both the sample result and the
blank results must be reported together.
    <IP_ADDRESS> In addition to reporting results for samples and blanks
separately, the concentration of each analyte in a blank associated
with the sample may be subtracted from the result for that sample, but
only if requested or required by a regulatory authority or in a permit.
In this case, both the sample result and the blank results must be
reported together.
    <IP_ADDRESS> Report a result for an analyte found in a sample or