5547 905R80111
METHOD 608.2: ANALYSIS OF CERTAIN ORGANOCHLORINE
PESTICIDES IN WASTEWATER BY GAS CHROMATOGRAPHY
1. SCOPE AND APPLICATION
1.1 This method covers the determination of certain organochlorine
pesticides in industrial and municipal wastewater. The following
parameters may be determined by this method.
Parameter STORET No. CAS No.
Chlorothalonil 1897-45-6
DCPA 39770 1861-32-1
Dichloran 99-30-9
Methoxychlor 39480 72-43-5
Permethrin 52645-53-1
1.2 The estimated detection limit (EDL) for each parameter is listed in
Table 1. The EDL was calculated from the minimum detectable
response of the electron capture detector equal to 5 times the
detector background noise assuming a 10.0 mL final extract volume
of a 1 L reagent water sample and a gas chromatographic (GC)
injection volume of 5 uL. The EDL for a specific wastewater may be
different depending on the nature of interferences in the sample
matrix.
1.3 This is a GC method applicable to the determination of the
compounds listed above in municipal and industrial discharges.
When this method is used to analyze unfamiliar samples for any or
all of the compounds listed above, compound identifications should
be supported by at least one additional qualitative technique.
Section 13 provides gas chromatograph/mass spectrometer (GC/MS)
conditions appropriate for the qualitative confirmation of compound
identifications.
1.4 This method is restricted to use by or under the supervision of
analysts experienced in the operation of gas chromatographs and in
the interpretation of chromatograms.
2. SUMMARY OF METHOD
2.1 Organochlorine pesticides are removed from the sample matrix by
extraction with methylene chloride. The extract is dried,
exchanged into hexane, and analyzed by gas chromatography. Column
chromatography is used as necessary to eliminate interferences
which may be encountered. Measurement of the pesticides is
accomplished with an electron capture detector.
2.2 Confirmatory analysis by gas chromatography/mass spectrometry is
recommended (Section 13) when a new or undefined sample type is
being analyzed if the concentration is adequate for such
determination.
U.S. Environmental Protection Agency
Region V, Library
230 South Dearborn Street
Chicago, Illinois 60604
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f
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Fnvlronmenta! Protection
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3. INTERFERENCES
3.1 Solvent, reagents, glassware, and other sample processing hardware
may yield discrete artifacts and/or elevated baselines causing
misinterpretation of gas chromatograms. All of these materials
must be demonstrated to be free from interferences under the con-
ditions of the analysis by running laboratory reagent blanks as
described in Section 9.1.
3.1.1 The use of high-purity reagents and solvents helps to
minimize interference problems. Purification of solvents by
distillation in all-glass systems may be required.
3.1.2 Glassware must be scrupulously cleaned (1). Clean all
glassware as soon as possible after use by rinsing with the
last solvent used in it. This should be followed by
detergent washing with hot water and rinses with tap water
and reagent water. It should then be drained dry and heated
in a muffle furnace at 400°C for 15 to 30 minutes. Solvent
rinses with acetone and pesticide-quality hexane may be
substituted for the muffle furnace heating. Volumetric ware
should not be heated in a muffle furnace. After drying and
cooling, glassware should be sealed and stored in a clean
environment to prevent any accumulation of dust or other
contaminants. Store the glassware inverted or capped with
aluminum foil.
3.2 Interferences co-extracted from the samples will vary considerably
from source to source, depending on the diversity of the industrial
complex or municipality being sampled. While general cleanup
procedures are provided as part of this method, unique samples may
. require additional cleanup approaches to achieve the detection
limits listed in Table 1.
4. SAFETY
4.1 The toxicity or carcinogenicity of each reagent used in this method
has not been precisely defined; however, each chemical compound
should be treated as a potential health hazard. From this
viewpoint, exposure to these chemicals must be reduced to the
lowest possible level by whatever means available. The laboratory
is responsible for maintaining a current awareness file of OSHA
regulations regarding the safe handling of the chemicals specified
in this method. A reference file of material data handling sheets
should also be made available to all personnel involved in the
chemical analysis. Additional references to laboratory safety are
available and have been identified (2-4) for the information of the
analyst.
5. APPARATUS AND EQUIPMENT
5.1 SAMPLE CONTAINERS - Narrow-mouth glass bottles, 1-liter or 1-quart
volume, equipped with polytetrafluoroethylene (PTFE)-lined screw
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caps. Wide-mouth glass bottles, 1-quart volume, equipped with
PTFE-lined screw caps may also be used. Prior to use, wash bottles
and cap liners with detergent and rinse with tap and distilled
water. Allow the bottles and cap liners to air dry, then muffle
the glass bottles at 400*C for 1 hour. After cooling, rinse the
cap liners with hexane, seal the bottles with aluminium foil, and
store in a dust-free environment.
5.1.1 Automatic sampler (optional)—Must incorporate glass sample
containers for the collection of a minimum of 250 ml.
Sample containers must be kept refrigerated at 4*C and
protected from light during compositing. If the sampler
uses a peristaltic pump, a minimum length of compressible
silicone rubber tubing may be used. Before use, however,
the compressible tubing should be thoroughly rinsed with
methanol, followed by repeated rinsings with distilled water
to minimize the potential for contamination of the sample.
An integrating flow meter is required to collect
flow-proportional composites.
5.2 KUDERNA-DANISH (K-D) GLASSWARE
5.2.1 Synder column—Three-ball macro (Kontes K-503000-0121 or
equivalent).
5.2.2 Concentrator tube—10-mL, graduated (Kontes K-570050-1025 or
equivalent) with ground glass stopper.
5.2.3 Evaporative flask—500-mL .(Kontes K-570001-0500 or
equivalent). Attach to concentrator tube with springs.
5.3 GAS CHROMATOGRAPHY SYSTEM
5.3.1 The gas chromatograph must be equipped with a glass-lined
injection port compatible with the detector to be used. A
data system is recommended for measuring peak areas.
5.3.1.1 Column 1—180 cm long by 2 mm ID, glass, packed with
1.5 percent OV-17/1.95 percent OV-210 on Chromosorb
W-HP (100/120 mesh) or equivalent.
5.3.1.2 Column 2—180 cm long x 2 mm ID, glass, packed with
4-percent SE-30/6-percent SP-2401 on Supelcoport
(100/120 mesh) or equivalent. Guidelines for the
use of alternate column packings are provided in
Section 10.3.1.
5.3.1.3 Detector—Electron capture. This detector has
proven effective in the analysis of wastewaters for
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the parameters listed in the scope and was used to
develop the method performance statements in Section
12. Guidelines for the use of alternate detectors
are provided in Section 10.3.1.
5.4 CHROMATOGRAPHIC COLUMN—400 mm long x 19 mm ID Chromaflex, equipped
with coarse fritted bottom plate and PTFE stopcock. (Kontes
K-420540-0224 or equivalent).
CHROMATOGRAPHIC COLUMN—300 mm long x 10 mm ID, equipped with
coarse fritted bottom plate and PFTE stopcock (Kontes K-430540-0213
or equivalent).
5.5 DRYING COLUMN—Approximately 400 mm long x 20 mm ID borosilicate
glass, equipped with coarse fitted bottom plate.
5.6 MISCELLANEOUS
5.6.1 Balance—analytical, capable of accurately weighing to the
nearest 0.0001 g.
5.6.2 Separatory funnel—two-liter, equipped with PTFE stopcock.
5.6.3 Water bath—heated with concentric ring cover, capable of
temperature control (±20C). The bath should be used in a
hood.
5.6.4 Standard solution storage containers—15-mL bottles with
PTFE-lined screw caps.
5.6.5 Boiling chips—approximately 10/40 mesh. Heat to 400*C for
30 minutes, or Soxhlet extract overnight with methylene
chloride.
6. REAGENTS AND CONSUMABLE MATERIALS
6.1 REAGENTS
6.1.1 Acetone, hexane, ethanol and methylene
chloride—demonstrated to be free of analytes.
6.1.2 Ethyl ether—Nanograde, redistilled in glass if necessary.
Must be free of peroxides as indicated by EM Quant test
strips. (Available from Scientific Products Co., Cat. No.
P1126-8, and other suppliers.) Procedures recommended for
removal of peroxides are provided with the test strips.
After cleanup, 20 mL ethyl alcohol preservative must be
added to each liter of ether.
6.1.3 Florisil—PR grade (60/100 mesh). Purchase activated at
1250°C and store in dark in glass containers with glass
stoppers or foil-lined screw caps. Before use, activate
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each batch overnight at 130*C in foil-covered glass
container.
6.1.4 Silica^gel—Activate approximately 100 grams of silica gel
at 200°C for 16 hours in a tared 500-ml Erlenmeyer flask
with ground glass stopper. Allow to cool to room
temperature, and determine the weight of activated silica
gel. Deactivate by adding 3 percent by weight of distilled
water. Restopper the flask, and shake on a wrist-action
shaker for at least 1 hour. Allow to equilibrate for 3 or
more hours at room temperature.
6.1.5 Reagent water—Reagent water is defined as a water in which
an interferent is not observed at the method detection limit
of each parameter of interest.
6.1.6 Sodium hydroxide (NaOH) solution (ION)—dissolve 40 g NaOH
in reagent water and dilute to 100 ml.
6.1.7 Sodium sulfate—granular, anydrous. Condition by heating at
400°C for 4 hours in a shallow tray.
6.1.8 Sulfuric acid (1^504) solution (1+1)—add measured
volume of concentrated H2S04 to equal volume of reagent
water.
6.2 STANDARD STOCK SOLUTIONS (1.00 wg/uL)—These solutions may be
purchased as certified solutions or prepared from pure standard
materials using the following procedures.
6.2.1 Prepare standard stock solutions by accurately weighing
about 0.0100 grams of pure material. Dissolve the material
in hexane or other suitable solvent and dilute to volume in
a 10-mL volumetric flask. Larger volumes can be used at the
convenience of the analyst. If compound purity is certified
at 96% or greater, the weight can be used without correction
to calculate the concentration of the standard stock.
6.2.2 Store standard stock solutions at 4*C in 15-mL bottles
equipped with PTFE-lined screw-caps. Standard stock
solutions should be checked frequently for signs of
degradation or evaporation, especially just prior to
preparing calibration standards from them.
6.2.3 Standard stock solutions must be replaced after 6 months or
sooner, if comparison with check standards indicates a
problem.
7. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
7.1 Collect all samples in duplicate. Grab samples must be collected
in glass containers. Conventional sampling practices (5) should be
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followed, except that the bottle must not .be prewashed with sample
before collection.
7.2 The samples must be iced or refrigerated at 4*C from the time of
collection until extraction. Chemical preservatives should not be
used in the field unless more than 24 hours will elapse before
extraction. If the samples will not be extracted within 48 hours
of collection, the sample should be adjuted to a pH range of 6.0 to
8.0 with sodium hydroxide or sulfuric acid.
7.3 All samples must be extracted within 7 days of collection, and
analyzed within 40 days of extraction. (6)
8. CALIBRATION AND STANDARDIZATION
8.1 CALIBRATION
8.1.1 A set of at least three calibration solutions containing the
method analytes is needed. One calibration solution should
contain each analyte at a concentration approaching but
greater than the EDL (Table 1) for that compound; the other
two solutions should contain analytes at concentrations that
bracket the range expected in samples. For example, if the
detection limit for a particular analyte is 0.2 ug/L, and a
sample expected to contain approximately 5 ug/l is analyzed,
standard solutions should be prepared at concentrations
representing 0.3 ug/L, 5 ug/L, and 10 yg/L of the analytes.
8.1.2 To prepare a calibration solution, add an appropriate volume
of a standard stock solution to a volumetric flask and
dilute to volume with hexane.
8.1.3 Starting with the standard of lowest concentration, analyze
each calibration standard according to Section 10.3.2 and
tabulate peak height or area responses versus the mass of
analyte injected. The results can be used to prepare a
calibration curve for each compound. Alternatively, if the
ratio of response to concentration (calibration factor) is a
constant over the working range (<10% relative standard
deviation), linearity through the origin can be assumed and
the average ratio or calibration factor can be used in place
of a calibration curve.
8.1.4 The working calibration curve or calibration factor must be
verified on each working day by the measurement of one or
more calibration standards. If the response for any analyte
varies from the predicted response by more than ±10%, the
test must be repeated using a fresh calibration standard.
If the results still do not agree, generate a new
calibration curve.
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8.2 FLORISIL STANDARDIZATION
8.2.1 Florisil from different batches or sources may vary in
absorptive capacity. To standardize the amount of Florisil
which may be used in the cleanup procedure (Section 10.2.2)
use of the lauric acid value (7) is suggested. The
referenced procedure determines the adsorption from hexane
solution of lauric acid (mg) per gram Florisil. The amount
of Florisil to be used for each column is calculated by
dividing this factor into 110 and multiplying by 20 g.
9. QUALITY CONTROL
9.1 MONITORING FOR INTERFERENCES
Analyze a laboratory reagent blank each time a set of samples is
extracted. A laboratory reagent blank is a one-liter aliquot of
reagent water. If the reagent blank contains a reportable level of
any analyte, immediately check the entire analytical system to
locate and correct for possible interferences and repeat the test.
9.2 ASSESSING ACCURACY
9.2.1 After every 10 samples, and preferably in the middle of each
day, analyze a laboratory control standard. Calibration
standards may not be used for accuracy assessments and the
laboratory control standrd may not be used for calibration
of the analytical system.
9.2.1.1 Laboratory Control Standard Concentrate - from stock
standards prepared as described in Section 6.3,
prepare a laboratory control standard concentrate
that contains each analyte of interest at a
concentration of 2 ng/mL in acetone or other
suitable solvent. (8)
9.2.1.2 Laboratory Control Standard - using a pipet, add
1.00 mL of the laboratory control standard
concentrate to a one-liter aliquot of reagent water.
9.2.1.3 Analyze the laboratory control standard as described
in Section 10. For each analyte in the laboratory
control standard, calculate the percent recovery
(Pj) with the equation:
loo s1
where S-j = the analytical results from the
laboratory control standard, in ug/L; and
T-j = the known concentration of the spike,
in
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9.2.2 At least annually, the laboratory should participate in
formal performance evaluation studies, where solutions of
unknown concentrations are analyzed and the performance of
all participants is compared.
9.3 ASSESSING PRECISION
9.3.1
9.3.2
Precision assessments for this method are based upon the
analysis of field duplicates (Section 7.1). Analyze both
sample bottles for at least 10% of all samples. To the
extent practical, the samples for duplication should contain
reportable levels of most of the analytes.
For each analyte in each duplicate pair, calculate the
relative range (RR-j) with the equation:
100 R,
RR.
9.3.3
10. PROCEDURE
A.
where Ri = the absolute difference between the
duplicate measurements X^ and X2, in
ug/L; and
X-j = the average concentration found ([Xj. +
X2]/2), in ug/L.
Individual relative range measurements are pooled to
determine average relative range or to develop an expression
of relative range as a function of concentration.
10.1 SAMPLE EXTRACTION
10.1.1 Mark the water meniscus on the side of the sample bottle for
later determination of sample volume. Pour the entire
sample into a 2-liter separatory funnel. Check the pH of
the sample with wide-range pH paper and adjust to within the
range of 5 to 9 with sodium hydroxide or sulfuric acid.
10.1.2 Add 60 mL of methylene chloride to the sample bottle and
shake for 30 seconds to rinse the walls. Transfer the
solvent to the separatory funnel and extract the sample by
shaking the funnel for 2 minutes with periodic venting to
release vapor pressure. Allow the organic layer to separate
from the water phase for a minimum of 10 minutes. If the
emulsion interface between layers is more than one-third the
volume of the solvent layer, the analyst must employ
mechanical techniques to complete the phase separation. The
optimum technique depends on the sample, but may include
stirring, filtration of the emulsion through glass wool, or
centrifugation. Collect the extract in a 250-mL Erlenmeyer
flask.
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10.1.3 Add an additional 60-mL volume of methylene chloride to the
sample bottle and complete the extraction procedure a second
time, combining the extracts in the Erlenmeyer flask.
10.1.4 Perform a third extraction in the same manner. Pour the
combined extract through a drying column containing about 10
cm of anhydrous sodium sulfate, and collect the extract in a
500-mL K-D flask equipped with a 10 mL concentrator tube.
Rinse the Erlenmeyer flask and column with 20 to 30 ml of
methylene chloride to complete the quantitative transfer.
10.1.5 Add one or two clean boiling chips to the flask and attach a
three-ball Snyder column. Prewet the Snyder column by
adding about 1 ml of methylene chloride to the top. Place
the K-D apparatus on a hot water bath (60 to 65*C) so that
the concentrator tube is partially immersed in the hot water
and the entire lower rounded surface of the flask is bathed
in steam. Adjust the vertical position of the apparatus and
the water temperature as required to complete the
concentration in 15 to 20 minutes. At the proper rate of
distillation, the balls of the column will actively chatter
but the chambers will not flood. When the apparent volume
of liquid reaches about 3 mL, remove the K-D apparatus and
allow it to drain and cool for at least 10 minutes.
10.1.6 Increase the temperature of the hot water bath to about 80
to 85*C. Momentarily remove the Snyder column, add 50 mL of
hexane and a new boiling chip, and reattach the Snyder
column* Pour about 1 mL of hexane into the top of the
Snyder column, and concentrate the solvent extract as
before. Elapsed time of concentration should be 5 to 10
minutes. When the apparent volume of liquid reaches about
3 mL, remove the K-D apparatus, and allow it to drain at
least 10 minutes while cooling. Remove the Snyder column,
rinse the flask and the lower joint into the concentrator
tube with 1 to 2 mL of hexane, and adjust the volume to
10 mL. A 5-mL syringe is recommended for this operation.
Stopper the concentrator tube, and store refrigerated if
further processing will not be performed immediately. If
the extracts will be stored longer than 2 days, they should
be transferred to Teflon-sealed screw-cap bottles. If the
sample extract requires no cleanup, proceed with gas
chromatographic analysis.
10.1.7 If the sample requires cleanup, the extract obtained must be
divided into two fractions. One of the fractions is eluted
through Florisil for the analysis of dicloran and DCPA. The
other fraction is eluted through silica gel for the analysis
of chlorothalonil, methoxychlor, and the permethrins.
10.1.8 Determine the original sample volume by refilling the sample
bottle to the mark and transferring the liquid to a 1,000 mL
graduated cylinder. Record the sample volume to the nearest
5 mL.
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10.2 CLEANUP AND SEPARATION
10.2.1 Cleanup procedures may not be necessary for a relatively
clean sample matrix. The cleanup procedures recommended in
this method have been used for the analysis of various clean
waters and municipal effluents. The single-operator
precision and accuracy data in Table 2 were gathered using
the recommended cleanup procedures. If particular
circumstances demand the use of an alternative cleanup
procedure, the analyst must determine the elution profile
and demonstrate that the recovery of each compound of
interest is no less than that recorded in Table 2.
10.2.2 Florisil Column Cleanup.
10.2.2.1 Add a weighed amount of Florisil, about 21 grams,
to a chromatographic column. The exact weight
should be determined by calibration. (7) Tap the
column to settle the Florisil. Add a 1- to 2-cm
layer of sodium sulfate above the Florisil. Rinse
the Florisil and sodium sulfate by adding 60 ml of
hexane to the column. Just prior to exposure of
the sodium sulfate to air, stop the draining of the
hexane by closing the stopcock on the column.
Discard the eluate.
10.2.2.2 Quantitatively, add the fraction of extract chosen
for the analysis of dichloran and DCPA to the
column. Drain the column into the flask, stopping
just prior to exposure of the sodium sulfate
layer.
10.2.2.3 Elute the column with 200 mL of 6-percent ethyl
ether in hexane (Fraction 1) using a drip rate of
about 5 mL/minute. Remove and discard. Perform a
second elution using 200 ml of 15-percent ethyl
ether in hexane (Fraction 2), collecting the eluant
in a 500 mL K-D flask equipped with a 10 mL
concentrator tube.
10.2.2.4 Concentrate the eluate by standard K-D techniques
(Paragraph 10.1.5), substituting hexane for
methylene chloride, and using the water bath at
about 85°C. Adjust the final volumes to 10 mL with
hexane. Analyze by gas chromatography.
10.2.3 Silica Gel Column Cleanup.
10.2.3.1 Prepare silica gel columns using a 300-mm by 10-mm
ID glass column.
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Rinse column with hexane. Add approximately 50 mL
of hexane to the empty column. Add 3.5 grams of
3-percent deactivated silica gel (Paragraph
6.1.4). Pack by rotating slowly to release air
bubbles. Top with 1.5 cm of Na2S04- Drain
hexane to the top of the
10.2.3.2 Add the fraction of extract chosen for the analysis
of chlorothalonil, methoxychlor, and the
permethrins to the column. Open the stopcock and
allow it to drain to the surface of the sodium
sulfate. Elute with the following solutions:
1st fraction — 25 ml of hexane,
2nd fraction — 25 mL of 6-percent MeClj in
hexane (volume/volume), and
3rd fraction — 25mL of 50-percent MeCl2 in
hexane.
10.2.3.3 Collect the third fraction in a 500 ml K-0 flask
equipped with a 10 mL concentrator tube, and add 50
mL of hexane. Concentrate on an 85°C water bath to
10.0 mL as described in Section 10.1.5.
10.2.4 The elution profiles obtained in these studies are listed in
Tables 3 and 4 for the convenience of the analyst. The
analyst must determine the elution profiles and demonstrate
that the recovery of each compound of interest is no lass
than that reported in Table 2 before the analysis of any
samples utilizing these cleanup procedures.
10.2.5 Proceed with gas chromatography.
10.3 GAS CHROMATOGRAPHIC ANALYSIS
10.3.1 Recommended columns and detector for the gas chromatographic
system are described in Section 5.3.1. Table 1 summarizes
the recommended operating conditions for the gas
chromatograph. Included in this table are estimated
retention times and detection limits that can be achieved by
this method. Examples of the separations achieved by Column
1 are shown in Figures 1 and 2. Other packed columns,
chromatographic conditions, or detectors may be used if data
quality comparable to Table 2 are achieved. Capillary
(open-tubular) columns may also be used if the relative
standard deviations of responses for replicate injections
are demonstrated to be less than 6 percent and data quality
comparable to Table 2 are achieved.
10.3.2 Inject 2 to 5 uL of the sample extract using the
solvent-flush technique (9). Record the volume injected to
the nearest 0.05 pL, the total extract volume, the fraction
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of total extract utilized in each cleanup scheme and the
resulting peak size in area or peak height units.
10.3.3 The width of the retention time window used to make
identifications should be based upon measurements of actual
retention time variations of standards over the course of
the day. Three times the standard deviation of a retention
time for a compound can be used to calculate a suggested
window size; however, the experience of the analyst should
weigh heavily in the interpretation of chromatograms.
10.3.4 If the response for the peak exceeds the working range of
the system, dilute the extract and reanalyze.
10.3.5 If the measurement of the peak response is prevented by the
presence of interferences, further cleanup is required.
11. CALCULATIONS
11.1 Determine the concentration (C) of individual compounds in the
sample in pg/L with the equation:
(A) (V ) (V )
C = l c
where A = amount of material injected, in nanograms;
V. = volume of extract injected, uL;
V. = volume of total extract, pL;
V = volume of water extracted, mL;
V = volume of final extract after cleanup (pL)
Vf = volume of extract utilized for cleanup scheme
(u/L)
11.2 Report the results for the unknown samples in ug/L. Round off the
results of the nearest 0.1 pg/L or two significant figures.
12. METHOD PERFORMANCE
12.1 Estimated detection limits (EDL) and associated chromatographic
conditions are listed in Table 1(10). The detection limits were
calculated from the minimum detectable response of the EC detector
equal to 5 times the background noise, assuming a 10.0-mL final
extract volume of a 1-liter sample and a GC injection of 5 uL.
12.2 Single laboratory accuracy and precision studies were conducted by
Environmental Science and Engineering, Inc. (6), using spiked
industrial wastewater samples. The results of these studies are
presented in Table 2.
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13. GC/MS CONFIRMATION
13.1 It is recommended that GC/MS techniques be judiciously employed to
support qualitative identifications made with this method. The
mass spectrometer should be capable of scanning the mass range from
35 AMU to a mass 50 AMU above the molecular weight of the
compound. The instrument must be capable of scanning the mass
range at a rate to produce at least 5 scans per peak, but not to
exceed 7 scans per peak utilizing a 70-V (nominal) electron energy
in the electron impact ionization mode. A GC to MS interface
constructed of all-glass or glass-lined materials is recommended.
A computer system should be interfaced to the mass spectrometer
that allows the continuous acquisition and storage on machine-
readable media of all mass spectra obtained throughout the duration
of the chromatographic program.
13.2 Gas chromatographic columns and conditions should be selected for
optimum separation and performance. The conditions selected must
be compatible with standard GC/MS operating practices.
Chromatographic tailing factors of less than 5.0 must be achieved.
The calculation of tailing factors is illustrated in Method 625.(11)
13.3 At the beginning of each day that confirmatory analyses are to be
performed, the GC/MS system must be checked to see that all DFTPP
performance criteria are achieved.(12)
13.4 To confirm an identification of a compound, the background
corrected mass spectrum of the compound must be obtained from the
sample extract and compared with a mass spectrum from a stock or
calibration standard analyzed under the same chromatographic
conditions. It is recommended that at least 25 nanograms of
material be injected into the GC/MS. The criteria below must be
met for qualitative confirmation.
13.4.1 The molecular ion and other ions that are present above
10-percent relative abundance in the mass spectrum of the
standard must be present in the mass spectrum of the sample
with agreement to plus or minus 10 percent. For example, if
the relative abundance of an ion is 30 percent in the mass
spectrum of the standard, the allowable limits for the
relative abundance of that ion in the mass spectrum for the
sample would be 20 to 40 percent.
13.4.2 The retention time of the compound in the sample must be
within 6 seconds of the same compound in the standard
solution.
13.4.3 Compounds that have similar mass spectra can be explicitly
identified by GC/MS only on the basis of retention time data.
13.5 Where available, chemical ionization mass spectra may be employed
to aid in the qualitative identification process.
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13.6 Should these MS procedures fail to provide satisfactory results,
additional steps may be taken before reanalysis. These may include
the use of alternate packed or capillary GC columns or additional
cleanup.
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REFERENCES
1. ASTM Annual Book of Standards, Part 31, 03694, "Standard Practice for
Preparation of Sample Containers and for Preservation," American Society
for Testing and Materials, Philadelphia, PA, p. 679, 1980.
2. "Carcinogens - Working with Carcinogens," Department of Health,
Education, and Welfare, Public Health Service, Center for Disease
Control, National Institute for Occupational Safety and Health,
Publication No. 77-206, August 1977.
3. "OSHA Safety and Health Standards, General Industry" (29 CFR 1910),
Occupational Safety and Health Administration, OSHA 2206 (Revised,
January 1976).
4. "Safety in Academic Chemistry Laboratories," American Chemical Society
Publication, Committee on Chemical Safety, 3rd Edition, 1979.
5. ASTM Annual Book of Standards, Part 31, D3370, "Standard Practice for
Sampling Water," American Society for Testing and Materials,
Philadelphia, PA, p. 76, 1980.
6. Test procedures for Pesticides in Wastewaters, EPA Contract Report
#68-03-2897. Unpublished report available from U.S. Environmental
Protection Agency, Environmental Monitoring and Support Laboratory,
Cincinnati, Ohio 45268.
7. Mills, P.A., "Variation of Floricil Activity: Simple Method for
Measuring Adsorbent Capacity and Its Use in Standardizing Florisil
Columns," Journal of the Association of Official Analytical Chemists,
51, 19 (196SJ7
8. "Handbook for Analytical Quality Control in Water and Wastewater
Laboratories," EPA-600/4-79-019, U.S. Environmental Protection Agency,
Environmental Monitoring and Support Laboratory - Cincinnati, Ohio
45268, March 1979.
9. Burke, J.A., "Gas Chromatography for Pesticide Residue Analysis; Some
Practical Aspects," Journal of the Association of Official Analytical
Chemists, 48, 1037 (1965).
10. "Evaluation of Ten Pesticide Methods," Contract #68-03-1760, Task '
No. 11, U.S. Environmental Protection Agency, Environmental Monitoring
and Support Laboratory, Cincinnati, Ohio 45268.
11. "Methods for Organic Chemical Analysis of Municipal and Industrial
Wastewater," EPA-600/4-82-057. U.S. Environmental Protection Agency,
Environmental Monitoring and Support Laboratory, Cincinnati, Ohio 45268.
12. Eichelberger, J.W., Harris, L.E., and Budde, W.L., Anal. Chem., 46, 1912
(1975).
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TABLE 1
GAS CHROMATOGRAPHY OF ORGANOCHLORINE PESTICIDES
Retention Time (minutes) Estimated Detection
Parameter
Chlorothalonil
DCPA
Dicloran
Methoxychlor
cis-Permethrin***
trans-Permethri n***
Column 1*
3.40
4.19
2.23
22.35
18.52
20.02
Column 2**
4.69
5.44
2.62
10.85
16.04
17.53
Limit (ug/L)
0.001
0.003
0.002
0.04
0.2
0.2
* Column 1: 180 cm long by 2 mm ID, glass, packed with 1.5-percent
OV-17/1.95-percent 0V 210 on Chromosorb W-HP (100/120 mesh) or
equivalent; 5-percent methane/95-percent Argon carrier gas at 30 mL/min
flow rate. Column temperature is 200*C, detector—electron capture.
** Column 2: 180 cm long by 2 mm ID, glass, packed with 4-percent
SE-30/6-percent SP-2401 on Supelcoport (100/120 mesh) or equivalent;
5-percent methane/95-percent Argon carrier gas at 60 mL/min flow rate.
Column temperature is 200*C, detector—electron capture.
*** Column temperature is 220°C.
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TABLE 2
SINGLE LABORATORY ACCURACY AND PRECISION
Parameter
Chlorothalonil
DCPA
Dicloran
Methoxychlor
cis-Permethrin
trans-Permethrin
Matrix
Type*
1
2
1
2
1
2
1
2
1
2
1
2
Spike
Range
(ug/L)
37.8
2,300
16
10,540
37.5
21,200
24.5
2,600
6.3
317
5.7
297
Number of
Replicates
7
7
7
7
7
7
7
7
7
7
7
7
Average
Percent
Recovery
84.1
94.9
77.6
89.5
98.6
90.8
102.4
102.2
99.5
77.5
78.8
88.9
Standard
Deviation
(%)
16.4
22.5
25.7
11.0
8.4
20.3
12.4
10.2
18.8
10.6
16.1
19.6
* 1 = Low-level industrial effluent.
2 = High-level industrial effluent.
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TABLE 3
ELUTION PROFILES FOR FLORISIL CLEANUP
Percent Recovery by Fraction*
Parameter I23~~
DCPA 0 99.3 0
Dicloran 0 96.3 0
* Eluting solvent composition for each fraction given in Section 10.2.2.3.
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TABLE 4
ELUTION PROFILES FOR SILICA GEL* CLEANUP
Percent Recovery by Fraction**
Parameter
Chlorothalonil
Methoxychlor
Cis-permethrin
Trans-Permethrin
1
0
0
0
0
2
0
0
0
0
3
93.8
93.8
107.2
92.5
* 3-Percent deactivated.
**Eluting solvent composition for each fraction given in Sections 10.2.3.2
and 10.2.3.3.
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c
c
13
20
6 3 10 12 14 16
Retention Tine (mm.)
GAS :::J5.0VATOG?-AM OF CHIQROTH£LO?!IL, OCrA, DICLORUJ, A;iO
M£TnO
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U.S. Environmental Protection Agency
Region V, Library
230 South Dearborn Street
o, Illinois 60604
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