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 13.2-13.4 to verify system performance. 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.
    13.3 GC resolution--The resolution should be verified on the
mid-point concentration of the initial calibration as well as the
laboratory designated continuing calibration verification level if
closely eluting isomers are to be reported (e.g.,
benzo(b)fluoranthene and benzo(k)fluoranthene). Sufficient gas
chromatographic resolution is achieved if the height of the valley
between two isomer peaks is less than 50% of the average of the two
peak heights.
    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 Analysis of DFTPP, the DDT/Endrin decomposition test (if
used), the LCS, and the blank are outside of the 12-hour analysis
shift (section 3.1). The total time for DFTPP, DDT/Endrin, the LCS,
the blank, and the 12-hour shift must not exceed 15 hours.
    13.8 Decomposition of DDT and endrin--If DDT and/or endrin are
to be determined, this test must be performed prior to calibration
verification (section 13.4). The QC acceptance criteria (section
13.8.3) must be met before analyzing samples for DDE and/or Endrin.
DDT decomposes to DDE and DDD. Endrin decomposes to endrin aldehyde
and endrin ketone.
    13.8.1 Inject 1 [mu]L of the DDT and endrin decomposition
solution (section 6.14). As noted in section 6.14, other injection
volumes may be used as long as the concentrations of DDT and endrin
in the solution are adjusted to introduce the masses of the two
analytes into the instrument that are listed in section 6.14.
    13.8.2 Measure the areas of the peaks for DDT, DDE, DDD, Endrin,
Endrin aldehyde, and Endrin ketone. Calculate the percent breakdown
as shown in the equations below:

[GRAPHIC] [TIFF OMITTED] TR28AU17.015

    13.8.3 Both the % breakdown of DDT and of Endrin must be less
than 20%, otherwise the system is not performing acceptably for DDT
and endrin. In this case, repair the GC column system that failed
and repeat the performance tests (sections 13.2 to 13.6) until the
specification is met.

    Note: DDT and endrin decomposition are usually caused by
accumulation of particulates in the injector and in the front end of
the column. Cleaning and silanizing the injection port liner, and
breaking off a short section of the front end of the column will
usually eliminate the decomposition problem. Either of these
corrective actions may affect retention times, GC resolution, and
calibration linearity.

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>). Identification of an analyte is
confirmed per sections 14.1.1 through 14.1.4.
    14.1.1 The signals for the quantitation and secondary 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 The retention time for the analyte should be within
 10 seconds of the analyte in the calibration
verification run at the beginning of the shift (section 7.3 or
13.4).

    Note: Retention time windows other than  10 seconds
may be appropriate depending on the performance of the gas
chromatograph or observed retention time drifts due to certain types
of matrix effects. Relative retention time (RRT) may be used as an
alternative to absolute retention times if retention time drift is a
concern. RRT is a unitless quantity (see Sec. 22.2), 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. When significant
retention time drifts are observed, dilutions or spiked samples may
help the analyst determine the effects of the matrix on elution of
the target analytes and to assist in qualitative identification.

    14.1.3 Either the background corrected EICP areas, or 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 the
quantitation and secondary 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.
If identification is ambiguous, an experienced spectrometrist
(section 1.7) must determine the presence or absence of the
compound.
    14.2 Structural isomers that produce very similar mass spectra
should be identified as individual isomers if they have sufficiently
different gas chromatographic retention times. Sufficient gas
chromatographic resolution is achieved if the height of the valley
between two isomer peaks is less than 50% of the average of the two
peak heights. 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] TR28AU17.016

where:

Cex = Concentration of the analyte in the extract, in
[micro]g/mL, and the other terms are as defined in section 7.2.2.
    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] TR28AU17.017

where:

Csamp = Concentration of the analyte in the sample
Cex = Concentration of the analyte in the extract, in
[micro]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 specified otherwise 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,'' ``limit of
quantitation,'' and ``minimum level'' to be synonymous.
    <IP_ADDRESS> Report a result for each analyte in each field sample
or QC standard at or above the ML to 3 significant figures. Report a
result for each analyte found in each field sample or QC standard
below the ML as ``ML'' where ML is the concentration of the analyte
at the ML, or as required by the regulatory/control authority or
permit. Report a result for each analyte in a blank at or above the
MDL to 2 significant figures. Report a result for each analyte found
in a blank below the MDL as ``MDL,'' where MDL is the concentration
of the analyte at the MDL, or as required by the regulatory/control
authority or permit.
    <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
extract that has been diluted at the least dilute level at which the
area at the quantitation m/z is within the calibration range (i.e.,
above the ML for the analyte) and the MS/MSD recovery and RPD are
within their respective QC acceptance criteria (Table 6). This may
require reporting results for some analytes from different analyses.
    15.2.3 Results from tests performed with an analytical system
that is not in control (i.e., that does not meet acceptance criteria
for any QC test in this method) must be documented and reported
(e.g., as a qualifier on results), unless the failure is not
required to be reported as determined by the regulatory/control
authority. Results associated with a QC failure cannot be used to
demonstrate regulatory compliance. QC failures do not relieve a
discharger or permittee of reporting timely results. If the holding
time would be exceeded for a re-analysis of the sample, the
regulatory/control authority should be consulted for disposition.

16. Method Performance

    16.1 The basic version of this method was tested by 15
laboratories using reagent water, drinking water, surface water, and
industrial wastewaters spiked at six concentrations over the range
5-1300 [mu]g/L (Reference 2). Single operator precision, overall
precision, and method accuracy were found to be directly related to
the concentration of the analyte and essentially independent of the
sample matrix. Linear equations to describe these relationships are
presented in Table 7.
    16.2 As noted in section 1.1, this method was validated through
an interlaboratory study in the early 1980s. However, the
fundamental chemistry principles used in this method remain sound
and continue to apply.
    16.3 A chromatogram of the combined acid/base/neutral
calibration standard is shown in Figure 2.

17. Pollution Prevention

    17.1 Pollution prevention encompasses any technique that reduces
or eliminates the quantity or toxicity of waste at the point of
generation. Many opportunities for pollution prevention exist in
laboratory operations. EPA has established a preferred hierarchy of
environmental management techniques that places pollution prevention
as the management option of first choice. Whenever feasible, the
laboratory should use pollution prevention techniques to address
waste generation. When wastes cannot be reduced at the source, the
Agency recommends recycling as the next best option.
    17.2 The analytes in this method are used in extremely small
amounts and pose little threat to the environment when managed
properly. Standards should be prepared in volumes consistent with
laboratory use to minimize the disposal of excess volumes of expired
standards. This method utilizes significant quantities of methylene
chloride. Laboratories are encouraged to recover and recycle this
and other solvents during extract concentration.
    17.3 For information about pollution prevention that may be
applied to laboratories and research institutions, consult Less is
Better: Laboratory Chemical Management for Waste Reduction,
available from the American Chemical Society's Department of
Governmental Relations and Science Policy, 1155 16th Street NW.,
Washington DC 20036,<PHONE_NUMBER>.

18. Waste Management

    18.1 The laboratory is responsible for complying with all
Federal, State, and local regulations governing waste management,
particularly the hazardous waste identification rules and land
disposal restrictions, and to protect the air, water, and land by
minimizing and controlling all releases from fume hoods and bench
operations. Compliance is also required with any sewage discharge
permits and regulations. An overview of requirements can be found in
Environmental Management Guide for Small Laboratories (EPA 233-B-98-
001).
    18.2 Samples at pH <2, or pH >12, are hazardous and must be
handled and disposed of as hazardous waste, or neutralized and
disposed of in accordance with all federal, state, and local
regulations. It is the laboratory's responsibility to comply with
all federal, state, and local regulations governing waste
management, particularly the hazardous waste identification rules
and land disposal restrictions. The laboratory using this method has
the responsibility to protect the air, water, and land by minimizing
and controlling all releases from fume hoods and bench operations.
Compliance is also required with any sewage discharge permits and
regulations. For further information on waste management, see ``The
Waste Management Manual for Laboratory Personnel,'' also available
from the American Chemical Society at the address in section 17.3.
    18.3 Many analytes in this method decompose above 500 [ordm]C.
Low-level waste such as absorbent paper, tissues, and plastic gloves
may be burned in an appropriate incinerator. Gross quantities of
neat or highly concentrated solutions of toxic or hazardous
chemicals should be packaged securely and disposed of through
commercial or governmental channels that are capable of handling
these types of wastes.
    18.4 For further information on waste management, consult The
Waste Management Manual for Laboratory Personnel and Less is Better-
Laboratory Chemical Management for Waste Reduction, available from
the American Chemical Society's Department of Government Relations
and Science Policy, 1155 16th Street NW., Washington, DC 20036, 202-
872-4477.

19. References

1. ``Sampling and Analysis Procedures for Screening of Industrial
Effluents for Priority Pollutants,'' U.S. Environmental Protection
Agency, Environmental Monitoring and Support Laboratory, Cincinnati,
Ohio 45268, March 1977, Revised April 1977.
2. ``EPA Method Study 30, Method 625, Base/Neutrals, Acids, and
Pesticides,'' EPA 600/4-84-053, National Technical Information
Service, PB84-206572, Springfield, Virginia 22161, June 1984.
3. 40 CFR part 136, appendix B.
4. Olynyk, P., Budde, W.L. and Eichelberger, J.W. ``Method Detection
Limit for Methods 624 and 625,'' Unpublished report, May 14, 1980.
5. Annual Book of ASTM Standards, Volume 11.02, D3694-96, ``Standard
Practices for Preparation of Sample Containers and for Preservation
of Organic Constituents,'' American Society for Testing and
Materials, Philadelphia.
6. Solutions to Analytical Chemistry Problems with Clean Water Act
Methods, EPA 821-R-07-002, March 2007.
7. ``Carcinogens-Working With Carcinogens,'' Department of Health,
Education, and Welfare, Public Health Service, Center for Disease
Control, National Institute for Occupational Safety and Health,
Publication No. 77-206, August 1977.
8. ``OSHA Safety and Health Standards, General Industry,'' (29 CFR
part 1910), Occupational Safety and Health Administration, OSHA 2206
(Revised, January 1976).
9. ``Safety in Academic Chemistry Laboratories,'' American Chemical
Society Publication, Committee on Chemical Safety, 7th Edition,
2003.
10. Johnson, R.A., and Wichern, D.W., ``Applied Multivariate
Statistical Analysis,'' 3rd edition, Prentice Hall, Englewood
Cliffs, NJ, 1992.
11. 40 CFR 136.6(b)(4)(x).
12. 40 CFR 136.6(b)(2)(i).
13. Protocol for EPA Approval of New Methods for Organic and
Inorganic Analytes in Wastewater and Drinking Water (EPA-821-B-98-
003) March 1999.
14. Provost, L.P. and Elder, R.S. ``Interpretation of Percent
Recovery Data,'' American Laboratory, 15, 58-63 (1983). (The value
2.44 used in the equation in section 8.3.3 is two times the value
1.22 derived in this report.)

15. ASTM Annual Book of Standards, Part 31, D3370-76. ``Standard
Practices for Sampling Water,'' American Society for Testing and
Materials, Philadelphia.
16. 40 CFR 136.3(a), Table IB, Chlorine--Total Residual.
17. ``Manual of Analytical Methods for the Analysis of Pesticides in
Human and Environmental Samples,'' EPA-600/8-80-038, U.S.
Environmental Protection Agency, Health Effects Research Laboratory,
Research Triangle Park, North Carolina.
18. Eichelberger, J.W., Harris, L.E., and Budde, W.L. ``Reference
Compound to Calibrate Ion Abundance Measurement in Gas
Chromatography-Mass Spectrometry,'' Analytical Chemistry, 47, 995
(1975).
19. Letter of approval of acceptance criteria for DFTPP for time-of-
flight mass spectrometers from William A. Telliard and Herb Brass of
EPA to Jack Cochran of LECO Corporation, February 9, 2005.

20. Tables

                            Table 1--Non Pesticide/PCB Base/Neutral Extractables \1\
----------------------------------------------------------------------------------------------------------------
                             Analyte                               CAS registry   MDL \4\ (ug/L)   ML \5\ (ug/L)
----------------------------------------------------------------------------------------------------------------
Acenaphthene....................................................         83-32-9             1.9             5.7
Acenaphthylene..................................................        208-96-8             3.5            10.5
Anthracene......................................................        120-12-7             1.9             5.7
Benzidine \2\...................................................         92-87-5              44             132
Benzo(a)anthracene..............................................         56-55-3             7.8            23.4
Benzo(a)pyrene..................................................         50-32-8             2.5             7.5
Benzo(b)fluoranthene............................................        205-99-2             4.8            14.4
Benzo(k)fluoranthene............................................        207-08-9             2.5             7.5
Benzo(ghi)perylene..............................................        191-24-2             4.1            12.3
Benzyl butyl phthalate..........................................         85-68-7             2.5             7.5
bis(2-Chloroethoxy)methane......................................        111-91-1             5.3            15.9
bis(2-Ethylhexyl)phthalate......................................        117-81-7             2.5             7.5
bis(2-Chloroisopropyl) ether (2,2'-Oxybis[1-chloropropane]).....        108-60-1             5.7            17.1
4-Bromophenyl phenyl ether......................................        101-55-3             1.9             5.7
2-Chloronaphthalene.............................................         91-58-7             1.9             5.7
4-Chlorophenyl phenyl ether.....................................       7005-72-3             4.2            12.6
Chrysene........................................................        218-01-9             2.5             7.5
Dibenz(a,h)anthracene...........................................         53-70-3             2.5             7.5
Di-n-butylphthalate.............................................         84-74-2             2.5             7.5
3,3'-Dichlorobenzidine..........................................         91-94-1            16.5            49.5
Diethyl phthalate...............................................         84-66-2             1.9             5.7
Dimethyl phthalate..............................................        131-11-3             1.6             4.8
2,4-Dinitrotoluene..............................................        121-14-2             5.7            17.1
2,6-Dinitrotoluene..............................................        606-20-2             1.9             5.7
Di-n-octylphthalate.............................................        117-84-0             2.5             7.5
Fluoranthene....................................................        206-44-0             2.2             6.6
Fluorene........................................................         86-73-7             1.9             5.7
Hexachlorobenzene...............................................        118-74-1             1.9             5.7
Hexachlorobutadiene.............................................         87-68-3             0.9             2.7
Hexachloroethane................................................         67-72-1             1.6             4.8
Indeno(1,2,3-cd)pyrene..........................................        193-39-5             3.7            11.1
Isophorone......................................................         78-59-1             2.2             6.6
Naphthalene.....................................................         91-20-3             1.6             4.8
Nitrobenzene....................................................         98-95-3             1.9             5.7
N-Nitrosodi-n-propylamine \3\...................................        621-64-7              --              --
Phenanthrene....................................................         85-01-8             5.4            16.2
Pyrene..........................................................        129-00-0             1.9             5.7
1,2,4-Trichlorobenzene..........................................        120-82-1             1.9             5.7
----------------------------------------------------------------------------------------------------------------
\1\ All analytes in this table are Priority Pollutants (40 CFR part 423, appendix A).
\2\ Included for tailing factor testing.
\3\ See section 1.2.
\4\ MDL values from the 1984 promulgated version of Method 625.
\5\ ML = Minimum Level--see Glossary for definition and derivation.

                                         Table 2--Acid Extractables \1\
----------------------------------------------------------------------------------------------------------------
                             Analyte                               CAS registry   MDL \3\ (ug/L)   ML \4\ (ug/L)
----------------------------------------------------------------------------------------------------------------
4-Chloro-3-methylphenol.........................................         59-50-7             3.0             9.0
2-Chlorophenol..................................................         95-57-8             3.3             9.9
2,4-Dichlorophenol..............................................        120-83-2             2.7             8.1
2,4-Dimethylphenol..............................................        105-67-9             2.7             8.1
2,4-Dinitrophenol...............................................         51-28-5              42             126
2-Methyl-4,6-dinitrophenol......................................        534-52-1              24              72
2-Nitrophenol...................................................         88-75-5             3.6            10.8
4-Nitrophenol...................................................        100-02-7             2.4             7.2
Pentachlorophenol \2\...........................................         87-86-5             3.6            10.8
Phenol..........................................................        108-95-2             1.5             4.5
2,4,6-Trichlorophenol...........................................         88-06-2             2.7             8.1
----------------------------------------------------------------------------------------------------------------
\1\ All analytes in this table are Priority Pollutants (40 CFR part 423, appendix A).

\2\ See section 1.2; included for tailing factor testing.
\3\ MDL values from the 1984 promulgated version of Method 625.
\4\ ML = Minimum Level--see Glossary for definition and derivation.

                                Table 3--Additional Extractable Analytes \1\, \2\
----------------------------------------------------------------------------------------------------------------
                             Analyte                               CAS registry   MDL \7\ (ug/L)   ML \8\ (ug/L)
----------------------------------------------------------------------------------------------------------------
Acetophenone....................................................         98-86-2  ..............  ..............
2-Acetylaminofluorene...........................................         53-96-3  ..............  ..............
1-Acetyl-2-thiourea.............................................        591-08-2  ..............  ..............
Alachlor........................................................      15972-60-8  ..............  ..............
Aldrin \3\......................................................        309-00-2             1.9             5.7
Ametryn.........................................................        834-12-8  ..............  ..............
2-Aminoanthraquinone............................................        117-79-3  ..............  ..............
Aminoazobenzene.................................................         60-09-3  ..............  ..............
4-Aminobiphenyl.................................................         92-67-1  ..............  ..............
3-Amino-9-ethylcarbazole........................................        132-32-1  ..............  ..............
Anilazine.......................................................        101-05-3  ..............  ..............
Aniline.........................................................         62-53-3  ..............  ..............
o-Anisidine.....................................................         90-04-0  ..............  ..............
Aramite.........................................................        140-57-8  ..............  ..............
Atraton.........................................................       1610-17-9  ..............  ..............
Atrazine........................................................       1912-24-9  ..............  ..............
Azinphos-methyl.................................................         86-50-0  ..............  ..............
Barban..........................................................        101-27-9  ..............  ..............
Benzanthrone....................................................         82-05-3  ..............  ..............
Benzenethiol....................................................        108-98-5  ..............  ..............
Benzoic acid....................................................         65-85-0  ..............  ..............
2,3-Benzofluorene...............................................        243-17-4  ..............  ..............
p-Benzoquinone..................................................        106-51-4  ..............  ..............
Benzyl alcohol..................................................        100-51-6  ..............  ..............
alpha-BHC \3\,\4\...............................................        319-84-6  ..............  ..............
beta-BHC \3\....................................................        319-85-7             3.1             9.3
gamma-BHC (Lindane) \3\,\4\.....................................         58-89-8             4.2            12.6
delta-BHC \3\...................................................        319-86-8  ..............  ..............
Biphenyl........................................................         92-52-4  ..............  ..............
Bromacil........................................................        314-40-9  ..............  ..............
2-Bromochlorobenzene............................................        694-80-4  ..............  ..............
3-Bromochlorobenzene............................................        108-39-2  ..............  ..............
Bromoxynil......................................................       1689-84-5  ..............  ..............
Butachlor.......................................................       2318-4669  ..............  ..............
Butylate........................................................       2008-41-5  ..............  ..............
n-C10 (n-decane)................................................        124-18-5  ..............  ..............
n-C12 (n-undecane)..............................................        112-40-2  ..............  ..............
n-C14 (n-tetradecane)...........................................        629-59-4  ..............  ..............
n-C16 (n-hexadecane)............................................        544-76-3  ..............  ..............
n-C18 (n-octadecane)............................................        593-45-3  ..............  ..............
n-C20 (n-eicosane)..............................................        112-95-8  ..............  ..............
n-C22 (n-docosane)..............................................        629-97-0  ..............  ..............
n-C24 (n-tetracosane)...........................................        646-31-1  ..............  ..............
n-C26 (n-hexacosane)............................................        630-01-3  ..............  ..............
n-C28 (n-octacosane)............................................        630-02-4  ..............  ..............
n-C30 (n-triacontane)...........................................        638-68-6  ..............  ..............
Captafol........................................................       2425-06-1  ..............  ..............
Captan..........................................................        133-06-2  ..............  ..............
Carbaryl........................................................         63-25-2  ..............  ..............
Carbazole.......................................................         86-74-8  ..............  ..............
Carbofuran......................................................       1563-66-2  ..............  ..............
Carboxin........................................................       5234-68-4  ..............  ..............
Carbophenothion.................................................        786-19-6  ..............  ..............
Chlordane \3\,\5\...............................................         57-74-9  ..............  ..............
bis(2-Chloroethyl) ether \3\,\4\................................        111-44-4             5.7            17.1
Chloroneb.......................................................       2675-77-6  ..............  ..............
4-Chloroaniline.................................................        106-47-8  ..............  ..............
Chlorobenzilate.................................................        510-15-6  ..............  ..............
Chlorfenvinphos.................................................        470-90-6  ..............  ..............
4-Chloro-2-methylaniline........................................         95-69-2  ..............  ..............
3-(Chloromethyl)pyridine hydrochloride..........................       6959-48-4  ..............  ..............
4-Chloro-2-nitroaniline.........................................         89-63-4  ..............  ..............
Chlorpropham....................................................        101-21-3  ..............  ..............
Chlorothalonil..................................................       1897-45-6  ..............  ..............
1-Chloronaphthalene.............................................         90-13-1  ..............  ..............
3-Chloronitrobenzene............................................        121-73-3  ..............  ..............
4-Chloro-1,2-phenylenediamine...................................         95-83-0  ..............  ..............

4-Chloro-1,3-phenylenediamine...................................       5131-60-2  ..............  ..............
2-Chlorobiphenyl................................................       2051-60-7  ..............  ..............
Chlorpyrifos....................................................       2921-88-2  ..............  ..............
Coumaphos.......................................................         56-72-4  ..............  ..............
m + p-Cresol....................................................      65794-96-9  ..............  ..............
o-Cresol........................................................         95-48-7  ..............  ..............
p-Cresidine.....................................................        120-71-8  ..............  ..............
Crotoxyphos.....................................................       7700-17-6  ..............  ..............
2-Cyclohexyl-4,6-dinitro-phenol.................................        131-89-5  ..............  ..............
Cyanazine.......................................................      21725-46-2  ..............  ..............
Cycloate........................................................       1134-23-2  ..............  ..............
p-Cymene........................................................         99-87-6  ..............  ..............
Dacthal (DCPA)..................................................       1861-32-1  ..............  ..............
4,4'-DDD \3\....................................................         72-54-8             2.8             8.4
4,4'-DDE \3\....................................................         72-55-9             5.6            16.8
4,4'-DDT \3\....................................................         50-29-3             4.7            14.1
Demeton-O.......................................................        298-03-3  ..............  ..............
Demeton-S.......................................................        126-75-0  ..............  ..............
Diallate (cis or trans).........................................       2303-16-4  ..............  ..............
2,4-Diaminotoluene..............................................         95-80-7  ..............  ..............
Diazinon........................................................        333-41-5  ..............  ..............
Dibenz(a,j)acridine.............................................        224-42-0  ..............  ..............
Dibenzofuran....................................................        132-64-9  ..............  ..............
Dibenzo(a,e)pyrene..............................................        192-65-4  ..............  ..............
Dibenzothiophene................................................        132-65-0  ..............  ..............
1,2-Dibromo-3-chloropropane.....................................         96-12-8  ..............  ..............
3,5-Dibromo-4-hydroxybenzonitrile...............................       1689-84-5  ..............  ..............
2,6-Di-tert-butyl-p-benzoquinone................................        719-22-2  ..............  ..............
Dichlone........................................................        117-80-6  ..............  ..............
2,3-Dichloroaniline.............................................        608-27-5  ..............  ..............
2,3-Dichlorobiphenyl............................................      16605-91-7  ..............  ..............
2,6-Dichloro-4-nitroaniline.....................................         99-30-9  ..............  ..............
2,3-Dichloronitrobenzene........................................       3209-22-1  ..............  ..............
1,3-Dichloro-2-propanol.........................................         96-23-1  ..............  ..............
2,6-Dichlorophenol..............................................        120-83-2  ..............  ..............
Dichlorvos......................................................         62-73-7  ..............  ..............
Dicrotophos.....................................................        141-66-2  ..............  ..............
Dieldrin \3\....................................................         60-57-1             2.5             7.5
1,2:3,4-Diepoxybutane...........................................       1464-53-5  ..............  ..............
Di(2-ethylhexyl) adipate........................................        103-23-1  ..............  ..............
Diethylstilbestrol..............................................         56-53-1  ..............  ..............
Diethyl sulfate.................................................         64-67-5  ..............  ..............
Dilantin (5,5-Diphenylhydantoin)................................         57-41-0  ..............  ..............
Dimethoate......................................................         60-51-5  ..............  ..............
3,3'-Dimethoxybenzidine.........................................        119-90-4  ..............  ..............
Dimethylaminoazobenzene.........................................         60-11-7  ..............  ..............
7,12-Dimethylbenz(a)anthracene..................................         57-97-6  ..............  ..............
3,3'-Dimethylbenzidine..........................................        119-93-7  ..............  ..............
N,N-Dimethylformamide...........................................         68-12-2  ..............  ..............
3,6-Dimethylphenathrene.........................................       1576-67-6  ..............  ..............
alpha, alpha-Dimethylphenethylamine.............................        122-09-8  ..............  ..............
Dimethyl sulfone................................................         67-71-0  ..............  ..............
1,2-Dinitrobenzene..............................................        528-29-0  ..............  ..............
1,3-Dinitrobenzene..............................................         99-65-0  ..............  ..............
1,4-Dinitrobenzene..............................................        100-25-4  ..............  ..............
Dinocap.........................................................      39300-45-3  ..............  ..............
Dinoseb.........................................................         88-85-7  ..............  ..............
Diphenylamine...................................................        122-39-4  ..............  ..............
Diphenyl ether..................................................        101-84-8  ..............  ..............
1,2-Diphenylhydrazine...........................................        122-66-7  ..............  ..............
Diphenamid......................................................        957-51-7  ..............  ..............
Diphenyldisulfide...............................................        882-33-7  ..............  ..............
Disulfoton......................................................        298-04-4  ..............  ..............
Disulfoton sulfoxide............................................       2497-07-6  ..............  ..............
Disulfoton sulfone..............................................       2497-06-5  ..............  ..............
Endosulfan I \3\,\4\............................................        959-98-8  ..............  ..............
Endosulfan II \3\,\4\...........................................      33213-65-9  ..............  ..............
Endosulfan sulfate \3\..........................................       1031-07-8             5.6            16.8
Endrin \3\,\4\..................................................         72-20-8  ..............  ..............
Endrin aldehyde \3\,\4\.........................................       7421-93-4  ..............  ..............
Endrin ketone \3\,\4\...........................................      53494-70-5  ..............  ..............

EPN.............................................................       2104-64-5  ..............  ..............
EPTC............................................................        759-94-4  ..............  ..............
Ethion..........................................................        563-12-2  ..............  ..............
Ethoprop........................................................      13194-48-4  ..............  ..............
Ethyl carbamate.................................................         51-79-6  ..............  ..............
Ethyl methanesulfonate..........................................         65-50-0  ..............  ..............
Ethylenethiourea................................................         96-45-7  ..............  ..............
Etridiazole.....................................................       2593-15-9  ..............  ..............
Ethynylestradiol-3-methyl ether.................................         72-33-3  ..............  ..............
Famphur.........................................................         52-85-7  ..............  ..............
Fenamiphos......................................................      22224-92-6  ..............  ..............
Fenarimol.......................................................      60168-88-9  ..............  ..............
Fensulfothion...................................................        115-90-2  ..............  ..............
Fenthion........................................................         55-38-9  ..............  ..............
Fluchloralin....................................................      33245-39-5  ..............  ..............
Fluridone.......................................................      59756-60-4  ..............  ..............
Heptachlor \3\..................................................         76-44-8             1.9             5.7
Heptachlor epoxide \3\..........................................       1024-57-3             2.2             6.6
2,2',3,3',4,4',6-Heptachlorobiphenyl............................      52663-71-5  ..............  ..............
2,2',4,4',5',6-Hexachlorobiphenyl...............................      60145-22-4  ..............  ..............
Hexachlorocyclopentadiene \3\,\4\...............................         77-47-4  ..............  ..............
Hexachlorophene.................................................         70-30-4  ..............  ..............
Hexachloropropene...............................................       1888-71-7  ..............  ..............
Hexamethylphosphoramide.........................................        680-31-9  ..............  ..............
Hexanoic acid...................................................        142-62-1  ..............  ..............
Hexazinone......................................................      51235-04-2  ..............  ..............
Hydroquinone....................................................        123-31-9  ..............  ..............
Isodrin.........................................................        465-73-6  ..............  ..............
2-Isopropylnaphthalene..........................................       2027-17-0  ..............  ..............
Isosafrole......................................................        120-58-1  ..............  ..............
Kepone..........................................................        143-50-0  ..............  ..............
Leptophos.......................................................      21609-90-5  ..............  ..............
Longifolene.....................................................        475-20-7  ..............  ..............
Malachite green.................................................        569-64-2  ..............  ..............
Malathion.......................................................        121-75-5  ..............  ..............
Maleic anhydride................................................        108-31-6  ..............  ..............
Merphos.........................................................        150-50-5  ..............  ..............
Mestranol.......................................................         72-33-3  ..............  ..............
Methapyrilene...................................................         91-80-5  ..............  ..............
Methoxychlor....................................................         72-43-5  ..............  ..............
2-Methylbenzothioazole..........................................        120-75-2  ..............  ..............
3-Methylcholanthrene............................................         56-49-5  ..............  ..............
4,4'-Methylenebis(2-chloroaniline)..............................        101-14-4  ..............  ..............
4,4'-Methylenebis(N,N-dimethylaniline)..........................        101-61-1  ..............  ..............
4,5-Methylenephenanthrene.......................................        203-64-5  ..............  ..............
1-Methylfluorene................................................       1730-37-6  ..............  ..............
Methyl methanesulfonate.........................................         66-27-3  ..............  ..............
2-Methylnaphthalene.............................................         91-57-6  ..............  ..............
Methylparaoxon..................................................        950-35-6  ..............  ..............
Methyl parathion................................................        298-00-0  ..............  ..............
1-Methylphenanthrene............................................        832-69-9  ..............  ..............
2-(Methylthio)benzothiazole.....................................        615-22-5  ..............  ..............
Metolachlor.....................................................       5218-45-2  ..............  ..............
Metribuzin......................................................      21087-64-9  ..............  ..............
Mevinphos.......................................................       7786-34-7  ..............  ..............
Mexacarbate.....................................................        315-18-4  ..............  ..............
MGK 264.........................................................        113-48-4  ..............  ..............
Mirex...........................................................       2385-85-5  ..............  ..............
Molinate........................................................       2212-67-1  ..............  ..............
Monocrotophos...................................................       6923-22-4  ..............  ..............
Naled...........................................................        300-76-5  ..............  ..............
Napropamide.....................................................      15299-99-7  ..............  ..............
1,4-Naphthoquinone..............................................        130-15-4  ..............  ..............
1-Naphthylamine.................................................        134-32-7  ..............  ..............
2-Naphthylamine.................................................         91-59-8  ..............  ..............
1,5-Naphthalenediamine..........................................       2243-62-1  ..............  ..............
Nicotine........................................................         54-11-5  ..............  ..............
5-Nitroacenaphthene.............................................        602-87-9  ..............  ..............
2-Nitroaniline..................................................         88-74-4  ..............  ..............
3-Nitroaniline..................................................         99-09-2  ..............  ..............
4-Nitroaniline..................................................        100-01-6  ..............  ..............

5-Nitro-o-anisidine.............................................         99-59-2  ..............  ..............
4-Nitrobiphenyl.................................................         92-93-3  ..............  ..............
Nitrofen........................................................       1836-75-5  ..............  ..............
5-Nitro-o-toluidine.............................................         99-55-8  ..............  ..............
Nitroquinoline-1-oxide..........................................         56-57-5  ..............  ..............
N-Nitrosodi-n-butylamine \ 4\...................................        924-16-3  ..............  ..............
N-Nitrosodiethylamine \4\.......................................         55-18-5  ..............  ..............
N-Nitrosodimethylamine \3\,\4\..................................         62-75-9  ..............  ..............
N-Nitrosodiphenylamine \3\,\4\..................................         86-30-6  ..............  ..............
N-Nitrosomethylethylamine \4\...................................      10595-95-6  ..............  ..............
N-Nitrosomethylphenylamine \4\..................................        614-00-6  ..............  ..............
N-Nitrosomorpholine \4\.........................................         59-89-2  ..............  ..............
N-Nitrosopiperidine \4\.........................................        100-75-5  ..............  ..............
N-Nitrosopyrrolidine \4\........................................        930-55-2  ..............  ..............
trans-Nonachlor.................................................      39765-80-5  ..............  ..............
Norflurazon.....................................................      27314-13-2  ..............  ..............
2,2',3,3',4,5',6,6'-Octachlorobiphenyl..........................      40186-71-8  ..............  ..............
Octamethyl pyrophosphoramide....................................        152-16-9  ..............  ..............
4,4'-Oxydianiline...............................................        101-80-4  ..............  ..............
Parathion.......................................................         56-38-2  ..............  ..............
PCB-1016 \3\,\5\................................................      12674-11-2  ..............  ..............
PCB-1221 \3\,\5\................................................      11104-28-2              30              90
PCB-1232 \3\,\5\................................................      11141-16-5  ..............  ..............
PCB-1242 \3\,\5\................................................      53469-21-9  ..............  ..............
PCB-1248 \3\,\5\................................................      12672-29-6  ..............  ..............
PCB-1254 \3\,\5\................................................      11097-69-1              36             108
PCB-1260 \3\,\5\................................................      11098-82-5  ..............  ..............
PCB-1268 \3\,\5\................................................      11100-14-4  ..............  ..............
Pebulate........................................................       1114-71-2  ..............  ..............
Pentachlorobenzene..............................................        608-93-5  ..............  ..............
Pentachloronitrobenzene.........................................         82-68-8  ..............  ..............
2,2',3,4',6-Pentachlorobiphenyl.................................      68194-05-8  ..............  ..............
Pentachloroethane...............................................         76-01-7  ..............  ..............
Pentamethylbenzene..............................................        700-12-9  ..............  ..............
Perylene........................................................        198-55-0  ..............  ..............
Phenacetin......................................................         62-44-2  ..............  ..............
cis-Permethrin..................................................      61949-76-6  ..............  ..............
trans-Permethrin................................................      61949-77-7  ..............  ..............
Phenobarbital...................................................         50-06-6  ..............  ..............
Phenothiazene...................................................         92-84-2  ..............  ..............
1,4-Phenylenediamine............................................        624-18-0  ..............  ..............
1-Phenylnaphthalene.............................................        605-02-7  ..............  ..............
2-Phenylnaphthalene.............................................        612-94-2  ..............  ..............
Phorate.........................................................        298-02-2  ..............  ..............
Phosalone.......................................................       2310-18-0  ..............  ..............
Phosmet.........................................................        732-11-6  ..............  ..............
Phosphamidon....................................................      13171-21-6  ..............  ..............
Phthalic anhydride..............................................         85-44-9  ..............  ..............
alpha-Picoline (2-Methylpyridine)...............................        109-06-8  ..............  ..............
Piperonyl sulfoxide.............................................        120-62-7  ..............  ..............
Prometon........................................................       1610-18-0  ..............  ..............
Prometryn.......................................................       7287-19-6  ..............  ..............
Pronamide.......................................................      23950-58-5  ..............  ..............
Propachlor......................................................       1918-16-7  ..............  ..............
Propazine.......................................................        139-40-2  ..............  ..............
Propylthiouracil................................................         51-52-5  ..............  ..............
Pyridine........................................................        110-86-1  ..............  ..............
Resorcinol (1,3-Benzenediol)....................................        108-46-3  ..............  ..............
Safrole.........................................................         94-59-7  ..............  ..............
Simazine........................................................        122-34-9  ..............  ..............
Simetryn........................................................       1014-70-6  ..............  ..............
Squalene........................................................       7683-64-9  ..............  ..............
Stirofos........................................................      22248-79-9  ..............  ..............
Strychnine......................................................         57-24-9  ..............  ..............
Styrene \9\.....................................................        100-42-5  ..............  ..............
Sulfallate......................................................         95-06-7  ..............  ..............
Tebuthiuron.....................................................      34014-18-1  ..............  ..............
Terbacil........................................................       5902-51-2  ..............  ..............
Terbufos........................................................      13071-79-9  ..............  ..............
Terbutryn.......................................................        886-50-0  ..............  ..............
alpha-Terpineol.................................................         98-55-5  ..............  ..............

1,2,4,5-Tetrachlorobenzene......................................         95-94-3  ..............  ..............
2,2',4,4'-Tetrachlorobiphenyl...................................       2437-79-8  ..............  ..............
2,3,7,8-Tetrachlorodibenzo-p-dioxin.............................       1746-01-6  ..............  ..............
2,3,4,6-Tetrachlorophenol.......................................         58-90-2  ..............  ..............
Tetrachlorvinphos...............................................      22248-79-9  ..............  ..............
Tetraethyl dithiopyrophosphate..................................       3689-24-5  ..............  ..............
Tetraethyl pyrophosphate........................................        107-49-3  ..............  ..............
Thianaphthene (2,3-Benzothiophene)..............................         95-15-8  ..............  ..............
Thioacetamide...................................................         62-55-5  ..............  ..............
Thionazin.......................................................        297-97-2  ..............  ..............
Thiophenol (Benzenethiol).......................................        108-98-5  ..............  ..............
Thioxanthone....................................................        492-22-8  ..............  ..............
Toluene-1,3-diisocyanate........................................      26471-62-5  ..............  ..............
Toluene-2,4-diisocyanate........................................        584-84-9  ..............  ..............
o-Toluidine.....................................................         95-53-4  ..............  ..............
Toxaphene \3\,\5\...............................................       8001-35-2  ..............  ..............
Triadimefon.....................................................      43121-43-3  ..............  ..............
1,2,3-Trichlorobenzene..........................................         87-61-6  ..............  ..............
2,4,5-Trichlorobiphenyl.........................................      15862-07-4  ..............  ..............
2,3,6-Trichlorophenol...........................................        933-75-5  ..............  ..............
2,4,5-Trichlorophenol...........................................         95-95-4  ..............  ..............
Tricyclazole....................................................      41814-78-2  ..............  ..............
Trifluralin.....................................................       1582-09-8  ..............  ..............
1,2,3-Trimethoxybenzene.........................................        634-36-6  ..............  ..............
2,4,5-Trimethylaniline..........................................        137-17-7  ..............  ..............
Trimethyl phosphate.............................................        512-56-1  ..............  ..............
Triphenylene....................................................        217-59-4  ..............  ..............
Tripropyleneglycolmethyl ether..................................      20324-33-8  ..............  ..............
1,3,5-Trinitrobenzene...........................................         99-35-4  ..............  ..............
Tris(2,3-dibromopropyl) phosphate...............................        126-72-7  ..............  ..............
Tri-p-tolyl phosphate...........................................         78-32-0  ..............  ..............
O,O,O-Triethyl phosphorothioate.................................        126-68-1  ..............  ..............
Trithiane.......................................................        291-29-4  ..............  ..............
Vernolate.......................................................       1929-77-7  ..............  ..............
----------------------------------------------------------------------------------------------------------------
\1\ Compounds that have been demonstrated amenable to extraction and gas chromatography.
\2\ Determine each analyte in the fraction that gives the most accurate result.
\3\ Priority Pollutant (40 CFR part 423, appendix A).
\4\ See section 1.2.
\5\ These compounds are mixtures of various isomers.
\6\ Detected as azobenzene.
\7\ MDL values from the 1984 promulgated version of Method 625.
\8\ ML = Minimum Level--see Glossary for definition and derivation.
\9\ Styrene may be susceptible to losses during sampling, preservation, and/or extraction of full-volume (1 L)
  water samples. However, styrene is not regulated at 40 CFR part 136, and it is also listed as an analyte in
  EPA Method 624.1 and EPA Method 1625C, where such losses may be less than using Method 625.1.

                               Table 4--Chromatographic Conditions and Characteristic m/z's for Base/Neutral Extractables
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Characteristic m/z's
                                                                Retention  -----------------------------------------------------------------------------
                           Analyte                             time  (sec)        Electron impact ionization                Chemical ionization
                                                                   \1\     -----------------------------------------------------------------------------
                                                                              Primary       Second       Second      Methane      Methane      Methane
--------------------------------------------------------------------------------------------------------------------------------------------------------
N-Nitrosodimethylamine.......................................          385           42           74           44  ...........  ...........  ...........
bis(2-Chloroethyl) ether.....................................          704           93           63           95           63          107          109
bis(2-Chloroisopropyl) ether.................................          799           45           77           79           77          135          137
Hexachloroethane.............................................          823          117          201          199          199          201          203
N-Nitrosodi-n-propylamine....................................          830          130           42          101  ...........  ...........  ...........
Nitrobenzene.................................................          849           77          123           65          124          152          164
Isophorone...................................................          889           82           95          138          139          167          178
bis(2-Chloroethoxy) methane..................................          939           93           95          123           65          107          137
1,2,4-Trichlorobenzene.......................................          958          180          182          145          181          183          209
Naphthalene..................................................          967          128          129          127          129          157          169
Hexachlorobutadiene..........................................         1006          225          223          227          223          225          227
Hexachlorocyclopentadiene....................................         1142          237          235          272          235          237          239
2-Chloronaphthalene..........................................         1200          162          164          127          163          191          203
Acenaphthylene...............................................         1247          152          151          153          152          153          181
Dimethyl phthalate...........................................         1273          163          194          164          151          163          164
2,6-Dinitrotoluene...........................................         1300          165           89          121          183          211          223
Acenaphthene.................................................         1304          154          153          152          154          155          183
2,4-Dinitrotoluene...........................................         1364          165           63          182          183          211          223

Fluorene.....................................................         1401          166          165          167          166          167          195
4-Chlorophenyl phenyl ether..................................         1409          204          206          141  ...........  ...........  ...........
Diethyl phthalate............................................         1414          149          177          150          177          223          251
N-Nitrosodiphenylamine.......................................         1464          169          168          167          169          170          198
4-Bromophenyl phenyl ether...................................         1498          248          250          141          249          251          277
alpha-BHC....................................................         1514          183          181          109  ...........  ...........  ...........
Hexachlorobenzene............................................         1522          284          142          249          284          286          288
beta-BHC.....................................................         1544          183          181          109  ...........  ...........  ...........
gamma-BHC....................................................         1557          181          183          109  ...........  ...........  ...........
Phenanthrene.................................................         1583          178          179          176          178          179          207
Anthracene...................................................         1592          178          179          176          178          179          207
delta-BHC....................................................         1599          183          109          181  ...........  ...........  ...........
Heptachlor...................................................         1683          100          272          274  ...........  ...........  ...........
Di-n-butyl phthalate.........................................         1723          149          150          104          149          205          279
Aldrin.......................................................         1753           66          263          220  ...........  ...........  ...........
Fluoranthene.................................................         1817          202          101          100          203          231          243
Heptachlor epoxide...........................................         1820          353          355          351  ...........  ...........  ...........
gamma-Chlordane..............................................         1834          373          375          377  ...........  ...........  ...........
Pyrene.......................................................         1852          202          101          100          203          231          243
Benzidine\ 2\................................................         1853          184           92          185          185          213          225
alpha-Chlordane..............................................         1854          373          375          377  ...........  ...........  ...........
Endosulfan I.................................................         1855          237          339          341  ...........  ...........  ...........
4,4'-DDE.....................................................         1892          246          248          176  ...........  ...........  ...........
Dieldrin.....................................................         1907           79          263          279  ...........  ...........  ...........
Endrin.......................................................         1935           81          263           82  ...........  ...........  ...........
Endosulfan II................................................         2014          237          339          341  ...........  ...........  ...........
4,4'-DDD.....................................................         2019          235          237          165  ...........  ...........  ...........
Endrin aldehyde..............................................         2031           67          345          250  ...........  ...........  ...........
Butyl benzyl phthalate.......................................         2060          149           91          206          149          299          327
Endosulfan sulfate...........................................         2068          272          387          422  ...........  ...........  ...........
4,4'-DDT.....................................................         2073          235          237          165  ...........  ...........  ...........
Chrysene.....................................................         2083          228          226          229          228          229          257
3,3'-Dichlorobenzidine.......................................         2086          252          254          126  ...........  ...........  ...........
Benzo(a)anthracene...........................................         2090          228          229          226          228          229          257
bis(2-Ethylhexyl) phthalate..................................         2124          149          167          279          149  ...........  ...........
Di-n-octyl phthalate.........................................         2240          149           43           57  ...........  ...........  ...........
Benzo(b)fluoranthene.........................................         2286          252          253          125          252          253          281
Benzo(k)fluoranthene.........................................         2293          252          253          125          252          253          281
Benzo(a)pyrene...............................................         2350          252          253          125          252          253          281
Indeno(1,2,3-cd) pyrene......................................         2650          276          138          277          276          277          305
Dibenz(a,h)anthracene........................................         2660          278          139          279          278          279          307
Benzo(ghi)perylene...........................................         2750          276          138          277          276          277          305
Toxaphene....................................................  ...........          159          231          233  ...........  ...........  ...........
PCB 1016.....................................................  ...........          224          260          294  ...........  ...........  ...........
PCB 1221.....................................................  ...........          190          224          260  ...........  ...........  ...........
PCB 1232.....................................................  ...........          190          224          260  ...........  ...........  ...........
PCB 1242.....................................................  ...........          224          260          294  ...........  ...........  ...........
PCB 1248.....................................................  ...........          294          330          262  ...........  ...........  ...........
PCB 1254.....................................................  ...........          294          330          362  ...........  ...........  ...........
PCB 1260.....................................................  ...........          330          362          394  ...........  ...........  ...........
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Column: 30 m x 0.25 mm ID; 94% methyl, 5% phenyl, 1% vinyl bonded phase fused silica capillary.
Conditions: 5 min at 30 [deg]C; 30-280 at 8 [deg]C per min; isothermal at 280 [deg]C until benzo(ghi)perylene elutes.
Gas velocity: 30 cm/sec at 30 [deg]C (at constant pressure).
\2\ See section 1.2; included for tailing factor testing.

                                   Table 5--Chromatographic Conditions and Characteristic m/z's for Acid Extractables
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Characteristic m/z's
                                                                Retention  -----------------------------------------------------------------------------
                           Analyte                             Time  (sec)        Electron impact ionization                Chemical ionization
                                                                   \1\     -----------------------------------------------------------------------------
                                                                               Prime        Second       Second      Methane      Methane      Methane
--------------------------------------------------------------------------------------------------------------------------------------------------------
2-Chlorophenol...............................................          705          128           64          130          129          131          157
Phenol.......................................................          700           94           65           66           95          123          135
2-Nitrophenol................................................          900          139           65          109          140          168          122
2,4-Dimethylphenol...........................................          924          122          107          121          123          151          163
2,4-Dichlorophenol...........................................          947          162          164           98          163          165          167

4-Chloro-3-methylphenol......................................         1091          142          107          144          143          171          183
2,4,6-Trichlorophenol........................................         1165          196          198          200          197          199          201
2,4-Dinitrophenol............................................         1325          184           63          154          185          213          225
4-Nitrophenol................................................         1354           65          139          109          140          168          122
2-Methyl-4,6-dinitrophenol...................................         1435          198          182           77          199          227          239
Pentachlorophenol............................................         1561          266          264          268          267          265          269
--------------------------------------------------------------------------------------------------------------------------------------------------------
Column: 30 m x 0.25 mm ID; 94% methyl, 5% phenyl, 1% vinyl bonded phase fused silica capillary.
Conditions: 5 min at 30 [deg]C; 30-250 at 8 [deg]C per min; isothermal at 280 [deg]C until pentachlorophenol elutes.
Gas velocity: 30 cm/sec at 30 [deg]C (at constant pressure).

                                 Table 6--QC Acceptance Criteria--Method 625 \1\
----------------------------------------------------------------------------------------------------------------
                                    Range for Q     Limit for s    Range for  X    Range for P1,  Limit for  RPD
             Analyte                  (%) \2\         (%) \3\         (%) \3\        P2(%) \3\          (%)
----------------------------------------------------------------------------------------------------------------
Acenaphthene....................          70-130              29          60-132          47-145              48
Acenaphthylene..................          60-130              45          54-126          33-145              74
Aldrin..........................           7-152              39           7-152           D-166              81
Anthracene......................          58-130              40          43-120          27-133              66
Benzo(a)anthracene..............          42-133              32          42-133          33-143              53
Benzo(b)fluoranthene............          42-140              43          42-140          24-159              71
Benzo(k)fluoranthene............          25-146              38          25-146          11-162              63
Benzo(a)pyrene..................          32-148              43          32-148          17-163              72
Benzo(ghi)perylene..............          13-195              61           D-195           D-219              97
Benzyl butyl phthalate..........          43-140              36           D-140           D-152              60
beta-BHC........................          42-131              37          42-131          24-149              61
delta-BHC.......................           D-130              77           D-120           D-120             129
bis(2-Chloroethyl)ether.........          52-130              65          43-126          12-158             108
bis(2-Chloroethoxy)methane......          52-164              32          49-165          33-184              54
bis(2-Chloroisopropyl) ether....          63-139              46          63-139          36-166              76
bis(2-Ethylhexyl) phthalate.....          43-137              50          29-137           8-158              82
4-Bromophenyl phenyl ether......          70-130              26          65-120          53-127              43
2-Chloronaphthalene.............          70-130              15          65-120          60-120              24
4-Chlorophenyl phenyl ether.....          57-145              36          38-145          25-158              61
Chrysene........................          44-140              53          44-140          17-168              87
4,4'-DDD........................           D-135              56           D-135           D-145              93
4,4'-DDE........................          19-130              46          19-120           4-136              77
4,4'-DDT........................           D-171              81           D-171           D-203             135
Dibenz(a,h)anthracene...........          13-200              75           D-200           D-227             126
Di-n-butyl phthalate............          52-130              28           8-120           1-120              47
3,3'-Dichlorobenzidine..........          18-213              65           8-213           D-262             108
Dieldrin........................          70-130              38          44-119          29-136              62
Diethyl phthalate...............          47-130              60           D-120           D-120             100
Dimethyl phthalate..............          50-130             110           D-120           D-120             183
2,4-Dinitrotoluene..............          53-130              25          48-127          39-139              42
2,6-Dinitrotoluene..............          68-137              29          68-137          50-158              48
Di-n-octyl phthalate............          21-132              42          19-132           4-146              69
Endosulfan sulfate..............           D-130              42           D-120           D-120              70
Endrin aldehyde.................           D-189              45           D-189           D-209              75
Fluoranthene....................          47-130              40          43-121          26-137              66
Fluorene........................          70-130              23          70-120          59-121              38
Heptachlor......................           D-172              44           D-172           D-192              74
Heptachlor epoxide..............          70-130              61          71-120          26-155             101
Hexachlorobenzene...............          38-142              33           8-142           D-152              55
Hexachlorobutadiene.............          68-130              38          38-120          24-120              62
Hexachloroethane................          55-130              32          55-120          40-120              52
Indeno(1,2,3-cd)pyrene..........          13-151              60           D-151           D-171              99
Isophorone......................          52-180              56          47-180          21-196              93
Naphthalene.....................          70-130              39          36-120          21-133              65
Nitrobenzene....................          54-158              37          54-158          35-180              62
N-Nitrosodi-n-propylamine.......          59-170              52          14-198           D-230              87
PCB-1260........................          19-130              77          19-130           D-164             128
Phenanthrene....................          67-130              24          65-120          54-120              39
Pyrene..........................          70-130              30          70-120          52-120              49
1,2,4-Trichlorobenzene..........          61-130              30          57-130          44-142              50
4-Chloro-3-methylphenol.........          68-130              44          41-128          22-147              73
2-Chlorophenol..................          55-130              37          36-120          23-134              61
2,4-Dichlorophenol..............          64-130              30          53-122          39-135              50

2,4-Dimethylphenol..............          58-130              35          42-120          32-120              58
2,4-Dinitrophenol...............          39-173              79           D-173           D-191             132
2-Methyl-4,6-dinitrophenol......          56-130             122          53-130           D-181             203
2-Nitrophenol...................          61-163              33          45-167          29-182              55
4-Nitrophenol...................          35-130              79          13-129           D-132             131
Pentachlorophenol...............          42-152              52          38-152          14-176              86
Phenol..........................          48-130              39          17-120           5-120              64
2,4,6-Trichlorophenol...........          69-130              35          52-129          37-144              58
----------------------------------------------------------------------------------------------------------------
\1\ Acceptance criteria are based upon method performance data in Table 7 and from EPA Method 1625. Where
  necessary, limits for recovery have been broadened to assure applicability to concentrations below those used
  to develop Table 7.
\2\ Test concentration = 100 [mu]g/mL.
\3\ Test concentration = 100 [mu]g/L.
Q = Calibration verification (sections 7.3.1 and 13.4).
s = Standard deviation for four recovery measurements in the DOC test (section 8.2.4).
X = Average recovery for four recovery measurements in the DOC test (section 8.2.4).
P1, P2 = MS/MSD recovery (section 8.3.2, section 8.4.2).
RPD = MS/MSD relative percent difference (RPD; section 8.3.3).
D = Detected; result must be greater than zero.

                  Table 7--Precision and Recovery as Functions of Concentration--Method 625 \1\
----------------------------------------------------------------------------------------------------------------
                                                                                Single analyst      Overall
                           Analyte                               Recovery, X'    precision, sr'   precision, S'
                                                                  ([mu]g/L)        ([mu]g/L)        ([mu]g/L)
----------------------------------------------------------------------------------------------------------------
Acenaphthene.................................................     0.96C + 0.19      0.15 X-0.12      0.21 X-0.67
Acenaphthylene...............................................     0.89C + 0.74      0.24 X-1.06      0.26 X-0.54
Aldrin.......................................................     0.78C + 1.66      0.27 X-1.28    0.43 X + 1.13
Anthracene...................................................     0.80C + 0.68      0.21 X-0.32      0.27 X-0.64
Benzo(a)anthracene...........................................       0.88C-0.60    0.15 X + 0.93      0.26 X-0.28
Benzo(b)fluoranthene.........................................       0.93C-1.80    0.22 X + 0.43    0.29 X + 0.96
Benzo(k)fluoranthene.........................................       0.87C-1.56    0.19 X + 1.03    0.35 X + 0.40
Benzo(a)pyrene...............................................       0.90C-0.13    0.22 X + 0.48    0.32 X + 1.35
Benzo(ghi)perylene...........................................       0.98C-0.86    0.29 X + 2.40      0.51 X-0.44
Benzyl butyl phthalate.......................................       0.66C-1.68    0.18 X + 0.94    0.53 X + 0.92
beta-BHC.....................................................       0.87C-0.94      0.20 X-0.58      0.30 X-1.94
delta-BHC....................................................       0.29C-1.09    0.34 X + 0.86      0.93 X-0.17
bis(2-Chloroethyl) ether.....................................       0.86C-1.54      0.35 X-0.99    0.35 X + 0.10
bis(2-Chloroethoxy) methane..................................       1.12C-5.04    0.16 X + 1.34    0.26 X + 2.01
bis(2-Chloroisopropyl) ether.................................       1.03C-2.31    0.24 X + 0.28    0.25 X + 1.04
bis(2-Ethylhexyl) phthalate..................................       0.84C-1.18    0.26 X + 0.73    0.36 X + 0.67
4-Bromophenyl phenyl ether...................................       0.91C-1.34    0.13 X + 0.66    0.16 X + 0.66
2-Chloronaphthalene..........................................     0.89C + 0.01    0.07 X + 0.52    0.13 X + 0.34
4-Chlorophenyl phenyl ether..................................     0.91C + 0.53      0.20 X-0.94      0.30 X-0.46
Chrysene.....................................................       0.93C-1.00    0.28 X + 0.13      0.33 X-0.09
4,4'-DDD.....................................................       0.56C-0.40      0.29 X-0.32      0.66 X-0.96
4,4'-DDE.....................................................       0.70C-0.54      0.26 X-1.17      0.39 X-1.04
4,4'-DDT.....................................................       0.79C-3.28    0.42 X + 0.19      0.65 X-0.58
Dibenz(a,h)anthracene........................................     0.88C + 4.72    0.30 X + 8.51    0.59 X + 0.25
Di-n-butyl phthalate.........................................     0.59C + 0.71    0.13 X + 1.16    0.39 X + 0.60
3,3'-Dichlorobenzidine.......................................      1.23C-12.65    0.28 X + 7.33    0.47 X + 3.45
Dieldrin.....................................................       0.82C-0.16      0.20 X-0.16      0.26 X-0.07
Diethyl phthalate............................................     0.43C + 1.00    0.28 X + 1.44    0.52 X + 0.22
Dimethyl phthalate...........................................     0.20C + 1.03    0.54 X + 0.19      1.05 X-0.92
2,4-Dinitrotoluene...........................................       0.92C-4.81    0.12 X + 1.06    0.21 X + 1.50
2,6-Dinitrotoluene...........................................       1.06C-3.60    0.14 X + 1.26    0.19 X + 0.35
Di-n-octyl phthalate.........................................       0.76C-0.79    0.21 X + 1.19    0.37 X + 1.19
Endosulfan sulfate...........................................     0.39C + 0.41    0.12 X + 2.47      0.63 X-1.03
Endrin aldehyde..............................................       0.76C-3.86    0.18 X + 3.91      0.73 X-0.62
Fluoranthene.................................................     0.81C + 1.10    0.22 X + 0.73      0.28 X-0.60
Fluorene.....................................................       0.90C-0.00    0.12 X + 0.26    0.13 X + 0.61
Heptachlor...................................................       0.87C-2.97      0.24 X-0.56      0.50 X-0.23
Heptachlor epoxide...........................................       0.92C-1.87      0.33 X-0.46    0.28 X + 0.64
Hexachlorobenzene............................................     0.74C + 0.66      0.18 X-0.10      0.43 X-0.52
Hexachlorobutadiene..........................................       0.71C-1.01    0.19 X + 0.92    0.26 X + 0.49
Hexachloroethane.............................................       0.73C-0.83    0.17 X + 0.67    0.17 X + 0.80
Indeno(1,2,3-cd)pyrene.......................................       0.78C-3.10    0.29 X + 1.46    0.50 X + 0.44
Isophorone...................................................     1.12C + 1.41    0.27 X + 0.77    0.33 X + 0.26
Naphthalene..................................................     0.76C + 1.58      0.21 X-0.41      0.30 X-0.68
Nitrobenzene.................................................       1.09C-3.05    0.19 X + 0.92    0.27 X + 0.21
N-Nitrosodi-n-propylamine....................................       1.12C-6.22    0.27 X + 0.68    0.44 X + 0.47

PCB-1260.....................................................      0.81C-10.86    0.35 X + 3.61    0.43 X + 1.82
Phenanthrene.................................................       0.87C-0.06    0.12 X + 0.57    0.15 X + 0.25
Pyrene.......................................................       0.84C-0.16    0.16 X + 0.06    0.15 X + 0.31
1,2,4-Trichlorobenzene.......................................       0.94C-0.79    0.15 X + 0.85    0.21 X + 0.39
4-Chloro-3-methylphenol......................................     0.84C + 0.35    0.23 X + 0.75    0.29 X + 1.31
2-Chlorophenol...............................................     0.78C + 0.29    0.18 X + 1.46    0.28 X + 0.97
2,4-Dichlorophenol...........................................     0.87C + 0.13    0.15 X + 1.25    0.21 X + 1.28
2,4-Dimethylphenol...........................................     0.71C + 4.41    0.16 X + 1.21    0.22 X + 1.31
2,4-Dinitrophenol............................................      0.81C-18.04    0.38 X + 2.36   0.42 X + 26.29
2-Methyl-4,6-Dinitrophenol...................................      1.04C-28.04   0.05 X + 42.29   0.26 X + 23.10
2-Nitrophenol................................................       1.07C-1.15    0.16 X + 1.94    0.27 X + 2.60
4-Nitrophenol................................................       0.61C-1.22    0.38 X + 2.57    0.44 X + 3.24
Pentachlorophenol............................................     0.93C + 1.99    0.24 X + 3.03    0.30 X + 4.33
Phenol.......................................................     0.43C + 1.26    0.26 X + 0.73    0.35 X + 0.58
2,4,6-Trichlorophenol........................................       0.91C-0.18    0.16 X + 2.22    0.22 X + 1.81
----------------------------------------------------------------------------------------------------------------
\1\ Regressions based on data from Reference 2.
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.

           Table 8--Suggested Internal and Surrogate Standards
------------------------------------------------------------------------
                                           Range for surrogate recovery
                                                      (%) \1\
          Base/neutral fraction          -------------------------------
                                            Calibration    Recovery from
                                           verification       samples
------------------------------------------------------------------------
Acenaphthalene-d8.......................          66-152          33-168
Acenaphthene-d10........................          71-141          30-180
Aniline-d5..............................  ..............  ..............
Anthracene-d10..........................          58-171          23-142
Benzo(a)anthracene-d12..................          28-357          22-329
Benzo(a)pyrene-d12......................          32-194          32-194
4-Chloroaniline-d4......................           1-145           1-145
bis(2-Chloroethyl) ether-d8.............          52-194          25-222
Chrysene-d12............................          23-290          23-290
Decafluorobiphenyl......................  ..............  ..............
4,4'-Dibromobiphenyl....................  ..............  ..............
4,4'-Dibromooctafluorobiphenyl..........  ..............  ..............
1,4-Dichlorobenzene-d4..................          65-153          11-245
2,2'-Difluorobiphenyl...................  ..............  ..............
Dimethyl phthalate-d6...................          47-211           1-500
Fluoranthene-d10........................          47-215          30-187
Fluorene-d10............................          61-164          38-172
4-Fluoroaniline.........................  ..............  ..............
1-Fluoronaphthalene.....................  ..............  ..............
2-Fluoronaphthalene.....................  ..............  ..............
2-Methylnaphthalene-d10.................          50-150          50-150
Naphthalene-d8..........................          71-141          22-192
Nitrobenzene-d5.........................          46-219          15-314
2,3,4,5,6-Pentafluorobiphenyl...........  ..............  ..............
Perylene-d12............................  ..............  ..............
Phenanthrene-d10........................          67-149          34-168
Pyrene-d10..............................          48-210          28-196
Pyridine-d5.............................  ..............  ..............
Acid fraction...........................  ..............  ..............
2-Chlorophenol-d4.......................          55-180          33-180
2,4-Dichlorophenol-d3...................          64-157          34-182
4,6-Dinitro-2-methylphenol-d2...........          56-177          22-307
2-Fluorophenol..........................  ..............  ..............
4-Methylphenol-d8.......................          25-111          25-111
2-Nitrophenol-d4........................          61-163          37-163
4-Nitrophenol-d4........................          35-287           6-500
Pentafluorophenol.......................  ..............  ..............
2-Perfluoromethylphenol.................  ..............  ..............
Phenol-d5...............................          48-208           8-424
------------------------------------------------------------------------
\1\ Recovery from samples is the wider of the criteria in the CLP SOW
  for organics or in Method 1625.

     Table 9A--DFTPP Key m/z's and Abundance Criteria for Quadrupole
                             Instruments \1\
------------------------------------------------------------------------
             m/z                          Abundance criteria
------------------------------------------------------------------------
51..........................  30-60 percent of m/z 198.
68..........................  Less than 2 percent of m/z 69.
70..........................  Less than 2 percent of m/z 69.
127.........................  40-60 percent of base peak m/z 198.
197.........................  Less than 1 percent of m/z 198.
198.........................  Base peak, 100 percent relative abundance.
199.........................  5-9 percent of m/z 198.
275.........................  10-30 percent of m/z 198.
365.........................  Greater than 1 percent of m/z 198.
441.........................  Present but less than m/z 443.
442.........................  40-100 percent of m/z 198.
443.........................  17-23 percent of m/z 442.
------------------------------------------------------------------------
\1\ Criteria in these tables are for quadrupole and time-of-flight
  instruments. Alternative tuning criteria from other published EPA
  reference methods may be used provided method performance is not
  adversely affected. Alternative tuning criteria specified by an
  instrument manufacturer may also be used for another type of mass
  spectrometer, provided method performance is not adversely affected.

   Table 9B--DFTPP Key m/z's and Abundance Criteria for Time-of-flight
                             Instruments \1\
------------------------------------------------------------------------
             m/z                          Abundance criteria
------------------------------------------------------------------------
51..........................  10-85 percent of the base peak.
68..........................  Less than 2 percent of m/z 69.
70..........................  Less than 2 percent of m/z 69.
127.........................  10-80 percent of the base peak.
197.........................  Less than 2 percent of Mass 198.
198.........................  Base peak, or greater than 50% of m/z 442.
199.........................  5-9 percent of m/z 198.
275.........................  10-60 percent of the base peak.
365.........................  Greater than 0.5 percent of m/z 198.
441.........................  Less than 150 percent of m/z 443.
442.........................  Base peak or greater than 30 percent of m/
                               z 198.
443.........................  15-24 percent of m/z 442.
------------------------------------------------------------------------
\1\ Criteria in these tables are for quadrupole and time-of-flight
  instruments. Alternative tuning criteria from other published EPA
  reference methods may be used provided method performance is not
  adversely affected. Alternative tuning criteria specified by an
  instrument manufacturer may also be used for another type of mass
  spectrometer, or for an alternative carrier gas, provided method
  performance is not adversely affected.

21. Figures
[GRAPHIC] [TIFF OMITTED] TR28AU17.018

[GRAPHIC] [TIFF OMITTED] TR28AU17.019

22. Glossary

    These definitions and purposes are specific to this method but
have been conformed to common usage to the extent possible.
    22.1 Units of weight and measure and their abbreviations.
    22.1.1 Symbols.
[deg]C degrees Celsius
[mu]g microgram
[mu]L microliter
< less than
> greater than
<= less than or equal to
% percent
    22.1.2 Abbreviations (in alphabetical order).
cm centimeter
g gram
h hour
ID inside diameter
in. inch
L liter
m mass or meter
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
    22.2 Definitions and acronyms (in alphabetical order).
    Analyte--A compound or mixture of compounds (e.g., PCBs) tested
for by this method. The analytes are listed in Tables 1-3.
    Batch--See Extraction.
    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.
    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 mid-point calibration
standard used to verify calibration. See sections 7.3 and 13.4.
    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.
    Extraction Batch--A set of up to 20 field samples (not including
QC samples) started through the extraction process on a given 24-
hour shift (section 3.1). Each extraction batch must be accompanied
by a blank (section 8.5), a laboratory control sample (LCS, section
8.4), and a matrix spike and duplicate (MS/MSD; Section 8.3),
resulting in a minimum of five analyses (1 sample, 1 blank, 1 LCS, 1
MS, and 1 MSD) and a maximum of 24 analyses (20 field samples, 1
blank, 1 LCS, 1 MS, and 1 MSD) for the batch. If greater than 20
samples are to be extracted in a 24-hour shift, the samples must be
separated into extraction batches of 20 or fewer samples.
    Field Duplicates--Two samples collected at the same time and
placed under identical conditions, and treated identically
throughout field and laboratory procedures. Results of analyses of
the 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 an extract or standard
solution in a known amount and used as a reference for quantitation
of the analytes of interest and surrogates. In this method the
internal standards are stable isotopically labeled analogs of
selected method analytes (Table 8). Also see Internal standard
quantitation.
    Internal standard quantitation--A means of determining the
concentration of an analyte of interest (Tables 1-3) by reference to
a compound not expected to be found in a sample.
    DOC--Initial demonstration of capability (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;
section 8.4)--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.
    Laboratory fortified sample matrix--See Matrix spike.
    Laboratory reagent blank--A blank run on laboratory reagents;
e.g., methylene chloride (section 11.1.5).
    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--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 Tables 1, 2
and 3. As noted in section 1.5, use the MDLs in Tables 1, 2, and 3
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, or matrix spike (a
QC sample type).
    MSD--Matrix spike duplicate (a QC sample type).
    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.
    Preparation blank--See blank.
    Quality control check sample (QCS)--See Laboratory Control
Sample.
    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 7.2.2.
    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 of
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.
    Should--This action, activity, or procedural step is suggested
but not required.
    SPE--Solid-phase extraction; an extraction technique in which an
analyte is extracted from an aqueous solution by passage over or
through a material capable of reversibly adsorbing the analyte. Also
termed liquid-solid extraction.
    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, authenticity, and concentration of the
standard.
    Surrogate--A compound unlikely to be found in a sample, and
which is spiked into sample in a known amount before extraction or
other processing, and is quantitated with the same procedures used
to quantify other sample components. The purpose of the surrogate is
to monitor method performance with each sample.
* * * * *

0
9. Appendix B to part 136 is revised to read as follows:

Appendix B to Part 136--Definition and Procedure for the Determination
of the Method Detection Limit--Revision 2

Definition

    The method detection limit (MDL) is defined as the minimum
measured concentration of a substance that can be reported with 99%
confidence that the measured concentration is distinguishable from
method blank results.

I. Scope and Application

    (1) The MDL procedure is designed to be a straightforward
technique for estimation of the detection limit for a broad variety
of physical and chemical methods. The procedure requires a complete,
specific, and well-defined analytical method. It is essential that
all sample processing steps used by the laboratory be included in
the determination of the method detection limit.
    (2) The MDL procedure is not applicable to methods that do not
produce results with a continuous distribution, such as, but not
limited to, methods for whole effluent toxicity, presence/absence
methods, and microbiological methods that involve counting colonies.
The MDL procedure also is not applicable to measurements such as,
but not limited to, biochemical oxygen demand, color, pH, specific
conductance, many titration methods, and any method where low-level
spiked samples cannot be prepared. Except as described in the
addendum, for the purposes of this procedure, ``spiked samples'' are
prepared from a clean reference matrix, such as reagent water,
spiked with a known and consistent quantity of the analyte. MDL
determinations using spiked samples may not be appropriate for all
gravimetric methods (e.g., residue or total suspended solids), but
an MDL based on method blanks can be determined in such instances.

II. Procedure

    (1) Estimate the initial MDL using one or more of the following:

    (a) The mean determined concentration plus three times the
standard deviation of a set of method blanks.
    (b) The concentration value that corresponds to an instrument
signal-to-noise ratio in the range of 3 to 5.
    (c) The concentration equivalent to three times the standard
deviation of replicate instrumental measurements of spiked blanks.
    (d) That region of the calibration where there is a significant
change in sensitivity, i.e., a break in the slope of the
calibration.
    (e) Instrumental limitations.
    (f) Previously determined MDL.

    Note: It is recognized that the experience of the analyst is
important to this process. However, the analyst should include some
or all of the above considerations in the initial estimate of the
MDL.

    (2) Determine the initial MDL.

    Note: The Initial MDL is used when the laboratory does not have
adequate data to perform the Ongoing Annual Verification specified
in Section (4), typically when a new method is implemented or if a
method was rarely used in the last 24 months.

    (a) Select a spiking level, typically 2--10 times the estimated
MDL in Section 1. Spiking levels in excess of 10 times the estimated
detection limit may be required for analytes with very poor recovery
(e.g., for an analyte with 10% recovery, spiked at 100 micrograms/L,
with mean recovery of 10 micrograms/L; the calculated MDL may be
around 3 micrograms/L. Therefore, in this example, the spiking level
would be 33 times the MDL, but spiking lower may result in no
recovery at all).
    (b) Process a minimum of seven spiked samples and seven method
blank samples through all steps of the method. The samples used for
the MDL must be prepared in at least three batches on three separate
calendar dates and analyzed on three separate calendar dates.
(Preparation and analysis may be on the same day.) Existing data may
be used, if compliant with the requirements for at least three
batches, and generated within the last twenty four months. The most
recent available data for method blanks and spiked samples must be
used. Statistical outlier removal procedures should not be used to
remove data for the initial MDL determination, since the total
number of observations is small and the purpose of the MDL procedure
is to capture routine method variability. However, documented
instances of gross failures (e.g., instrument malfunctions,
mislabeled samples, cracked vials) may be excluded from the
calculations, provided that at least seven spiked samples and seven
method blanks are available. (The rationale for removal of specific
outliers must be documented and maintained on file with the results
of the MDL determination.)
    (i) If there are multiple instruments that will be assigned the
same MDL, then the sample analyses must be distributed across all of
the instruments.
    (ii) A minimum of two spiked samples and two method blank
samples prepared and analyzed on different calendar dates is
required for each instrument. Each analytical batch may contain one
spiked sample and one method blank sample run together. A spiked
sample and a method blank sample may be analyzed in the same batch,
but are not required to be.
    (iii) The same prepared extract may be analyzed on multiple
instruments so long as the minimum requirement of seven preparations
in at least three separate batches is maintained.
    (c) Evaluate the spiking level: If any result for any individual
analyte from the spiked samples does not meet the method qualitative
identification criteria or does not provide a numerical result
greater than zero, then repeat the spiked samples at a higher
concentration. (Qualitative identification criteria are a set of
rules or guidelines for establishing the identification or presence
of an analyte using a measurement system. Qualitative identification
does not ensure that quantitative results for the analyte can be
obtained.)
    (d) Make all computations as specified in the analytical method
and express the final results in the method-specified reporting
units.
    (i) Calculate the sample standard deviation (S) of the replicate
spiked sample measurements and the sample standard deviation of the
replicate method blank measurements from all instruments to which
the MDL will be applied.
    (ii) Compute the MDLs (the MDL based on spiked
samples) as follows:

MDLS = t(n -1, 1-[alpha] = 0.99)Ss

Where:

MDLs = the method detection limit based on spiked samples
t(n-1, 1-[alpha] = 0.99) = the Student's t-
value appropriate for a single-tailed 99th percentile t statistic
and a standard deviation estimate with n-1 degrees of freedom. See
Addendum Table 1.
Ss = sample standard deviation of the replicate spiked
sample analyses.

    (iii) Compute the MDLb (the MDL based on method
blanks) as follows:
    (A) If none of the method blanks give numerical results for an
individual analyte, the MDLb does not apply. A numerical
result includes both positive and negative results, including
results below the current MDL, but not results of ``ND'' (not
detected) commonly observed when a peak is not present in
chromatographic analysis.
    (B) If some (but not all) of the method blanks for an individual
analyte give numerical results, set the MDLb equal to the
highest method blank result. If more than 100 method blanks are
available, set MDLb to the level that is no less than the
99th percentile of the method blank results. For ``n'' method blanks
where n >= 100, sort the method blanks in rank order. The (n * 0.99)
ranked method blank result (round to the nearest whole number) is
the MDLb. For example, to find MDLb from a set
of 164 method blanks where the highest ranked method blank results
are . . . 1.5, 1.7, 1.9, 5.0, and 10, then 164 x 0.99 = 162.36 which
rounds to the 162nd method blank result. Therefore, MDLb
is 1.9 for n = 164 (10 is the 164th result, 5.0 is the 163rd result,
and 1.9 is the 162nd result). Alternatively, you may use spreadsheet
algorithms to calculate the 99th percentile to interpolate between
the ranks more precisely.
    (C) If all of the method blanks for an individual analyte give
numerical results, then calculate the MDLb as:

MDLb = X + tn-1,1-[alpha]
= (0.99)Sb
Where:

MDLb = the MDL based on method blanks
X = mean of the method blank results (use zero in place of the mean
if the mean is negative)
t(n-1, 1[alpha] = 0.99) = the Student's t-
value appropriate for the single-tailed 99th percentile t statistic
and a standard deviation estimate with n-1 degrees of freedom. See
Addendum Table 1.
Sb = sample standard deviation of the replicate method
blank sample analyses.

    Note: If 100 or more method blanks are available, as an option,
MDLb may be set to the concentration that is greater than
or equal to the 99th percentile of the method blank results, as
described in Section (2)(d)(iii)(B).

    (e) Select the greater of MDLs or MDLb as
the initial MDL.
    (3) Ongoing Data Collection.
    (a) During any quarter in which samples are being analyzed,
prepare and analyze a minimum of two spiked samples on each
instrument, in separate batches, using the same spiking
concentration used in Section 2. If any analytes are repeatedly not
detected in the quarterly spiked sample analyses, or do not meet the
qualitative identification criteria of the method (see section 2(c)
of this procedure), then this is an indication that the spiking
level is not high enough and should be adjusted upward. Note that it
is not necessary to analyze additional method blanks together with
the spiked samples, the method blank population should include all
of the routine method blanks analyzed with each batch during the
course of sample analysis.
    (b) Ensure that at least seven spiked samples and seven method
blanks are completed for the annual verification. If only one
instrument is in use, a minimum of seven spikes are still required,
but they may be drawn from the last two years of data collection.
    (c) At least once per year, re-evaluate the spiking level.
    (i) If more than 5% of the spiked samples do not return positive
numerical results that meet all method qualitative identification
criteria, then the spiking level must be increased and the initial
MDL re-determined following the procedure in section 2.
    (ii) [Reserved]
    (d) If the method is altered in a way that can be reasonably
expected to change its sensitivity, then re-determine the initial
MDL according to section 2, and the restart the ongoing data
collection.
    (e) If a new instrument is added to a group of instruments whose
data are being pooled to create a single MDL, analyze a minimum of
two spiked replicates and two method blank replicates on the new
instrument. If both method blank results are below the existing MDL,
then the existing MDLb is validated. Combine the new
spiked sample results to the existing spiked sample results and
recalculate the MDLs as in Section 4. If the recalculated
MDLs does not vary by more than the factor specified in
section 4(f) of this

procedure, then the existing MDLs is validated. If either
of these two conditions is not met, then calculate a new MDL
following the instructions in section 2.
    (4) Ongoing Annual Verification.
    (a) At least once every thirteen months, re-calculate
MDLs and MDLb from the collected spiked
samples and method blank results using the equations in section 2.
    (b) Include data generated within the last twenty four months,
but only data with the same spiking level. Only documented instances
of gross failures (e.g., instrument malfunctions, mislabeled
samples, cracked vials) may be excluded from the calculations. (The
rationale for removal of specific outliers must be documented and
maintained on file with the results of the MDL determination.) If
the laboratory believes the sensitivity of the method has changed
significantly, then the most recent data available may be used,
maintaining compliance with the requirement for at least seven
replicates in three separate batches on three separate days (see
section 2b).
    (c) Include the initial MDL spiked samples, if the data were
generated within twenty four months.
    (d) Only use data associated with acceptable calibrations and
batch QC. Include all routine data, with the exception of batches
that are rejected and the associated samples reanalyzed. If the
method has been altered in a way that can be reasonably expected to
change its sensitivity, then use only data collected after the
change.
    (e) Ideally, use all method blank results from the last 24
months for the MDLb calculation. The laboratory has the
option to use only the last six months of method blank data or the
fifty most recent method blanks, whichever criteria yields the
greater number of method blanks.
    (f) The verified MDL is the greater of the MDLs or
MDLb. If the verified MDL is within 0.5 to 2.0 times the
existing MDL, and fewer than 3% of the method blank results (for the
individual analyte) have numerical results above the existing MDL,
then the existing MDL may optionally be left unchanged. Otherwise,
adjust the MDL to the new verification MDL. (The range of 0.5 to 2.0
approximates the 95th percentile confidence interval for the initial
MDL determination with six degrees of freedom.)

Addendum to Section II: Determination of the MDL for a Specific Matrix

    The MDL may be determined in a specific sample matrix as well as
in reagent water.
    (1) Analyze the sample matrix to determine the native
(background) concentration of the analyte(s) of interest.
    (2) If the response for the native concentration is at a signal-
to-noise ratio of approximately 5-20, determine the matrix-specific
MDL according to Section 2 but without spiking additional analyte.
    (3) Calculate MDLb using the method blanks, not the
sample matrix.
    (4) If the signal-to-noise ratio is less than 5, then the
analyte(s) should be spiked into the sample matrix to obtain a
concentration that will give results with a signal-to-noise ratio of
approximately 10-20.
    (5) If the analytes(s) of interest have signal-to-noise ratio(s)
greater than approximately 20, then the resulting MDL is likely to
be biased high.

           Table 1--Single-Tailed 99th Percentile t Statistic
------------------------------------------------------------------------
                                            Degrees of
          Number of replicates             freedom (n-1)   t (n-1, 0.99)
------------------------------------------------------------------------
7.......................................               6           3.143
8.......................................               7           2.998
9.......................................               8           2.896
10......................................               9           2.821
11......................................              10           2.764
16......................................              15           2.602
21......................................              20           2.528
26......................................              25           2.485
31......................................              30           2.457
32......................................              31           2.453
48......................................              47           2.408
50......................................              49           2.405