EPA-600/4-85-072 App.
APPENDIX A
THE DETERMINATION OF OITHIOCARBAMATES PESTICIDES
~1N WASTEWATER AS CARBON OISULFIDE BY ... _. - _,_
GAS CHROMATOGRAPHY DRAFT
METHOD 630.1
1. SCOPE AND APPLICATION
1.1 This method covers the determination of certain dithiocarbamates
pesticides after conversion to carbon disulfide. The following
parameters can be determined by this method:
Parameter CAS. Ko«
Amobam 3566-10-7
Susan 40 51026-28-9
Bus an 85 128-03-0
EXD - -''•:•'*•• 502-55-6
Ferbam 14484-54-1
KN Methyl 137-41-7
Metham 137-42-8
Nab am 142-59-5
Nabonate 138-93-2
Sodium dimethyl dithiocarbamate 128-04-1
Thiram 137-26-8
Zineb 12122-67-7
137-30-4
1.2 The compounds are decomposed to form carbon disulfide (CS?3 and
the total dithiocarbamate concentration is measured from the amount
of CS2 produced by acid hydrolysis. Unless the sample can be
otherwise characterized, all results are reported as Ziram.
1.3 This is a total residue gas chroma to graphic (GC) method applicable
to the determination of the compounds listed above in municipal and
industrial discharges as provided under 40 CFR 136.1. Any
US. Environmental Protection Agency
32 Region V, Library
230 South Dearborn Street
Chicago. fUinols 60604
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modification of this method beyond those expressly permitted,
shall be considered a major modification subject to application
and approval of alternate test, procedures under 40 CFR 136.4
and 136.5,
1.4 The method detection limits {MDLs, defined in Section 14)
for the parameters listed in Section 1.1 are listed in Table 1.
The MOLs for a specific wastewater may differ from those
listed, depending upon the nature of interferences in the
sample matrix.
1.5 This method is restricted to use by or under the supervision .
of analysts experienced in the use of gas chromatography and in
the interpretation of gas chromatograms. Each analyst must
demonstrate the ability to generate acceptable results with
this method using the procedure described in Section 8.2.
2. SUMMARY OF METHOD1
2.1 A measured volume of sample, 5 ml, is digested with acid to
yield CS2 by hydrolysis of the dithiocarbamate moiety. The
evolved CS* is extracted from water into hexane. Gas
chromatographic conditions are described which permit the
separation and measurement of CS^in the extract_by gas
chromatography with a Hall detector in the sulfur mode.
2.2 This method provides a cleanup procedure involving purging
of any indigenous CS2 from the sample at pH 12-13. This
procedure is performed using a vortex evaporator.
3. INTERFERENCES
3.1 Method interferences may be caused by contaminants in solvents,
reagents, glassware, and other sample processing apparatus that
lead to discrete artifacts or elevated baselines in gas
chromatograms. All reagents and apparatus must be routinely
demonstrated to be free from interferences under the conditions
of the analysis by running laboratory reagent blanks as
described in Section 8.5.
33
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2
3.1.1 Glassware must be scrupulously cleaned .
Clean all glassware as soon as possible after use by
thoroughly rinsing with the last solvent used 1n 1t,
Follow by washing with hot water,drain dry, and heat in
an oven or muffle furnace at 400°C for 15-30 minutes.
Do not heat volumetric ware. Some thermally stable
materials such as PCBs may not be eliminated by this
treatment. Thorough rinsing with acetone and pesticide
quality hexane may be substituted for the heating.
After drying and cooling, seal and store glassware in a
clean environment to prevent any accumulation of dust or
other contaminants. Store inverted or capped with
aluminum foil.
3.1.2 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.
3.2 Carbon disulfide may be a direct interferent in wastewaters.
This method includes procedures to purge CS2 from the
wastewater prior to acid hydrolysis of the sample. A vortex
evaporator is used for CS^ removal.
3.3 Additional matrix interferences may be caused by contaminants
that are coextracted from the sample and from other C$2
generating compounds. The extent of matrix interferences will
vary considerably from source to source, depending upon the
nature of the sample.
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
34
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handling of the chemicals specified 1n this method. A
reference file of material data handling sheets should also
be made available to all personnel Involved 1n the chemical
analysis. Additional references to laboratory safety are
3-5
available and have been Identified for the Information
of the analyst.
4.2 Nabam (ethylenebls(dithiocarbamate)) has been Identified as
having substantial evidence of cardnogenicity and should
be handled according to OSHA regulations.
5. APPARATUS AND MATERIALS
5,1 Sampling equipment, for discrete or composite sampling.
5.1.1 Sample containers - 40-mL screw cap vials (Pierce
No. 13075 or equivalent) each equipped with a
polytetrafluoroethylene (PTFE)-faced silicone
septum (Pierce No. 12722 or equivalent). Prior
to use, wash vials and septa with detergent and
rinse with tap and distilled water. Allow the
vials and septa to air dry at room temperature,
place in a 105°C oven for one hour, then remove
and allow to cool in an area known to be free of
• organics.
5.1.2 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 compres-
sible 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 Glassware
5.2.1 Centrifuge tube - 15-mL, conical with Teflon-lined
screw cap.
35
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5.2.2 Volumetric flask - 250-mL with glass stopper.
5.2.3 Bottles - 100- to 200-mL capacity with Teflon-lined
screw caps.
5.3 Vortex Evaporator - Buchler 3-2200, equipped with sample
block to hold 36 15-mL conical bottom centrifuge tubes and
appropriate vacuum cover.
5.4 Water bath - Heated, capable of temperature control (±2°C).
The bath should be used in a hood.
5.5 Balance - Analytical, capable of accurately weighing to the
nearest 0.0001 g.
5.6 Gas chromatograph - Analytical system complete with gas
chromatograph suitable for on-column injection and all required
accessories including syringes, analytical columns, gases,
detector, and strip-chart recorder. A data system is recommended
for measuring peak areas.
5.6.1 Column - 180 cm x 2 mm ID glass, packed with
O.U SP-1000 on Carbopack C (80/100 mesh) or equivalent.
This column was used to develop the method performance
statements in Section 14. Alternate columns may be used
in accordance with the provisions described in Section
11.1.
5.6.2 Detector - Hall detector operated in the sulfur mode.
This detector has proven effective in the analysis of
wastewaters for the compounds listed in the scope and was
used to develop the method performance statements in
Section 14.
6. REAGENTS
6.1 Reagent water - Reagent water is defined as a water in which
an interferent is not observed at the MDL of each parameter
of interest.
6.2 Hexane - Distilled-in-glass quality or equivalent.
6.3 Sulfuric acid, 12 N - Slowly add 100 ml concentrated sulfuric
acid to 200 ml reagent water.
6.4 Sodium phosphate, tribasic, dodeca-hydrate - Baker reagent
grade or equivalent.
36
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6.5 Tribasic sodium phosphate, 0.1 M - Dissolve 38 g of tribasic
sodium phosphate in reagent water and dilute to 1000 ml with
reagent water.
6.6 Stannous chloride - SnCl2 2H20, ACS grade.
6.7 Stannous chloride reagent - Dissolve 1.5 g stannous chloride
in 100 ml 12 N_ sulfuric acid. Prepare fresh daily.
6.8 Sodium chloride - Heated at 450°C for eight hours.
6.9 Stock standard solutions (0.1 yg/yL) - Stock standard
solutions can be prepared from pure standard materials
or purchased as certified solutions.
6.9.1 Prepare dithiocarbamate spiking solutions by
accurately weighing about 0.025 grams of pure
material. Dissolve the material in 0.1 M
Na3P04 and dilute to volume in a 250-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 stock standard.
Commercially prepared stock standards can be used
at any concentration if they are certified by the
manufacturer or by an independent source.
6.9.2 (0.1 yg/yL) Prepare C$2 stock standard solution
by adding 7.9 yL of CS2 to hexane and diluting
to volume in a 100-mL volumetric flask.
6.9.3 Transfer the stock standard solutions into
Teflon-sealed screw cap bottles. Store at 4°C.
Frequently check standard solutions for signs
of degradation or evaporation.
6.9.4 Stock standard solutions must be replaced after
six months or sooner if comparison with check
standards indicates a problem.
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7. CALIBRATION
7.1 Use zlram as the standard for total dithlocarbamates
when a mixture of dithlocarbamates is likely to be
present. Use the specific dithiocarbamate as a standard
when only one pesticide is present and its identity has
been established.
7.2 Establish gas chromatographie operating parameters equivalent
to those indicated in Table 1. The gas chromatographic
system can be calibrated using the external standard technique
(Section 7.3).
7.3 External standard calibration procedure:
7.3.1 Prepare calibration standards at a minimum of three
concentration levels by adding volumes of the CS-
stock standard to a volumetric flask and diluting
to volume with hexane. One of the external standards
should be at a concentration near, but above, the
method detection limit. The other concentrations
should correspond to the range of concentrations
expected in the sample concentrates or should define
the working range of the detector.
7.3.2 Using injections of 1 to 5 pL of each calibration
standard, tabulate peak height or area responses
against the mass injected. The results can be
used to prepare a calibration curve for CS-.
Alternatively, the ratio of the response to the
mass injected, defined as the calibration factor
(CF), can be calculated at each standard concen-
tration. If the relative standard deviation of
the calibration factor is less than 10% over the
working range, the average calibration factor can
be used in place of a calibration curve.
7.3.3 -The working calibration curve or calibration factor
must be verified on each working shift by the
measurement of one or more calibration standards.
38
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If the response for CS- varies from the predicted
response by more than ±10%, the test must be
repeated using a fresh calibration standard.
Alternatively, a new calibration curve or
calibration factor must be prepared.
7.4 Before using any cleanup procedure, the analyst must process
a series of calibration standards through the procedure to
validate the absence of interferences from the reagents.
8. QUALITY CONTROL
8.1 Each laboratory using this method is required to operate a
formal quality control program. The minimum requirements of
this program consist of an initial demonstration of laboratory
capability and the analysis of spiked samples as a continuing
check on performance. The laboratory is required to maintain
performance records to define the quality of data that is
generated.
8.1.1 Before performing any analyses, the analyst must
demonstrate the ability to generate acceptable accuracy
and precision with this method. This ability is
established as described in Section 8.2.
8.1.2 In recognition of the rapid advances occurring in
chromatography, the analyst is permitted certain options
to improve the separations or lower the cost of
measurements. Each time such modifications to the
method are made, the analyst is required to repeat the
procedure in Section 8.2.
8.1.3 The laboratory must spike and analyze a minimum of
10% of all samples to monitor continuing laboratory
performance. This procedure is described in Section 8.4.
8.2 To establish the ability to generate acceptable accuracy
and precision, the analyst must perform the following
operations.
8.2.1 Select a representative spike concentration for each
compound to be measured.
39
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8.2.2 Add a known amount of an Individual d1th1ocarbamate
standard to a minimum of four 5-mL allquots of 0.1 M
tribasic sodium phosphate. A representative waste-
water may be used in place of the reagent water, but
one or more additional allquots must be analyzed to
determine background levels, and the spike level must
exceed twice the background level for the test to be
valid. Analyze the aliquots according to the method
beginning in Section 10.
8.2.3 Calculate the average percent recovery (R), and the
standard deviation of the percent recovery (s), for the
results. Wastewater background corrections must be made
before R and s calculations are performed.
8.2.4 Using the appropriate data from Table 2, determine the
recovery and single operator precision expected for the
method, and compare these results to the values measured
in Section 8.2.3. If the data are not comparable, the
analyst must review potential problem areas and repeat
the test.
8.3 The analyst must calculate method performance criteria and
define the performance of the laboratory for each spike
concentration and parameter being measured.
8.3.1 Calculate upper and lower control limits for method
performance as follows:
Upper Control Limit (UCL) = "R + 3 s
Lower Control Limit (LCD - Fl - 3 s
where R and S are calculated as in Section 8.2.3. The
UCL and LCL can be used to construct control charts6
that are useful in observing trends in performance.
8.3.2 The laboratory must develop and maintain separate accuracy
statements of laboratory performance for wastewater
samples. An accuracy statement for the method is
40
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defined as R ± s. The accuracy statement should be
developed by the analysis of four allquots of wastewater
as described in Section 8.2.2, followed by the
calculation of R and s. Alternately, the analyst may
use four wastewater data points gathered through the
requirement for continuing quality control in Section
8.4. The accuracy statements should be updated
regularly.
8.4 The laboratory is required to collect in duplicate a portion
of their samples to monitor spike recoveries. The frequency of
spiked sample analysis must be at least 10% of all samples or
one sample per month, whichever is greater. One aliquot of the
sample must be spiked and analyzed as described in Section 8.2.
If the recovery for a particular compound does not fall within
the control limits for method performance, the results reported
for that compound in all samples processed as part of the same
set must be qualified as described in Section 12.3. The
laboratory should monitor the frequency of data so qualified to
ensure that it remains at or below 5%.
8.5 Before processing any samples, the analyst should demonstrate
though the analysis of a 5-ml aliquot of 0.1 M tribasic
sodium phosphate that all glassware and reagents interferences
are under control. Each time a set of samples is extracted or
there is a change in reagents, a laboratory reagent blank
should be processes as a safeguard against laboratory
contamination.
8.6 It is recommended that the laboratory adopt additional
quality assurance practices for use with this method.
The specific practices that are most productive depend
upon the needs of the laboratory and the nature of the
samples. Field duplicates may be analyzed to monitor
the precision of the sampling technique. When doubt
exists over the identification of a peak on the chromatogram,
confirmatory techniques such as gas chromatography
41
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with a dissimilar column, specific element detector,
or mass spectrometer must be used. Whenever possible,
the laboratory should perform analysis of standard
reference materials and participate in relevant performance
evaluation studies.
9. SAMPLES COLLECTION. PRESERVATION. AND HANDLING
9.1 Grab samples must be collected in glass containers.
Conventional sampling practices should be followed;
however, the bottle must not be prerinsed with sample
before collection. Composite samples should be collected
in refrigerated glass containers in accordance with the
requirements of the program. Automatic sampling equipment
must be as free as possible of plastic and other potential
sources of contamination.
9.2 The samples must be iced or refrigerated at 4° C from
the time of collection until extraction.
9.3 Add 15.2 g of tribasic sodium phosphate per 40 ml of sample
to the sample to adjust pH to 12-13 at time of collection.
10. SAMPLE CLEANUP AND EXTRACTION
10.1 Place 5 ml of sample in a 15-mL conical centrifuge tube.
10.2 Add 0.75 g of NaCl and shake tube to dissolve salt.
10.3 Add 2 ml of MTBE and process in a vortex evaporator
for 10 min with the temperature at 30°C, a vacuum
of 30 inches Hg, and the vortex speed control set at 4.5.
10.4 Repeat step 10.3 twice.
10.5 Add 0.75 ml of hexane and 2.5 ml of SnC^ reagent to
the aqueous layer. Cap tube tightly and invert in a
water bath at 50°C for 30 min.
10.6 Remove tube from water bath and let cool inverted
to room temperatue.
10.7 Shake tube for 1 min without venting. Analyze the hexane
layer by GC with a Hall detector in the sulfur mode.
42
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If CS- levels are outside of the GC calibration
range, the sample can be diluted a known amount with
hexane and reanalyzed.
11. GAS CHROMATOGRAPHY
11.1 Table 1 summarizes the recommended operating conditions for
the gas chromatograph. Included in this table are estimated
retention time and MDLs that can be achieved by this method.
An example of the chromatography achieved Column 1 is shown
in Figure 1. Other packed columns, chromatographic conditions,
or detectors may be used if the requirements of Section 8.2
are met. 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% and the
requirements of Section 8.2 are met.
11.2 Calibrate the gas chromatographic system daily as described
in Section 7.
11.3 Inject 1 to 5 yl of the sample extract using the solvent
flush technique**. Record the volume injected to the
nearest 0.05 H, and the resulting peak sizes in area
or peak height units. An automated system that consistently
injects a constant volume of extract may also be used.
11.4 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 a 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.
11.5 If the response for the peak exceeds the working range
of the system, dilute the extract with hexane and reanalyze.
11.6 If the measurement of the peak response is prevented
by the presence of interferences, further cleanup is
required.
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12. CALCULATIONS
12.1 Determine the concentration of carbon disulfide in the
sample.
12.1.1 If the external standard calibration procedure
is used, calculate the amount of material injected
from the peak response using the calibration
curve or calibration factor in Section 7.2.2.
The concentration of dithiocarbamate in the
sample can be calculated as follows:
Concentration, Ug/L =
where:
A = Amount of C$2 injected, in nanograms
V- = Volume of extract injected in yL.
Vt = Volume of total extract in vl.
V * Volume of water extracted in mL.
M » Molecular weight of dithiocarbamate
C = Theoretical number of moles of CS?
formed per mole of dithiocarbamate.
12.2 Determine the concentration of total dithiocarbamates in
the sample as ziram. When a specific dithiocarbamate is
being measured, quantitate in terms of the selected
pesticide.
12.3 Report results in micrograms per liter without correction
for recovery data. When duplicate and spiked samples are
analyzed, report all data obtained with the sample results.
12.4 For samples processed as part of a set where the laboratory
spiked sample recovery falls outside of the control limits
in Section 8.3, data for the affected compounds must be
labeled as suspect.
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13. METHOD PERFORMANCE
13.1 The MDL 1s defined as the minimum concentration of a substance
that can be measured and reported with 99% confidence that the
t(
1
q
value is above zero. The MDL concentrations listed in Table 1
were obtained using spiked reagent water samples.
13.2 This method has been tested for linearity of recovery from
spiked reagent water and has been demonstrated to be
applicable over the concentration range from 10 yg/L to
1000 yg/L.
13.3 In a single laboratory, Battelle Columbus Laboratories,
using spiked wastewater samples, the average recoveries
of the parameters listed in Section 1.1 presented in
Table 2 were obtained. Seven replicates of the wastewater
were spiked and analyzed. The standard deviation of the
percent recovery is also included in Table 2.
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REFERENCES
1. "Determination of Pesticides and Priority Pollutants in Industrial
and Municipal Wastewaters," Report for EPA Contract 68-03-1760-
Work Assignment 4 (In preparation).
2. ASTM Annual Book of Standards, Part 31, D3694, "Standard
Practice for Preparation of Sample Containers and for Preservation,"
American Society for Testing and Materials, Philadelphia,
PA, p. 679, 1980.
3. "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.
4. "OSHA Safety and Health Standards, General Industry," (29 CFR
1910), Occupational Safety and Health Administration, OSHA 2206
(Revised, January 1976).
5. "Safety in Academic Chemistry Laboratories," American Chemical
Society Publication, Committee on Chemical Safety, 3rd Edition,
1979.
6. "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.
7. ASTM Annual Book of Standards, Part 31, D3370, "Standard
Practice for Sampling Water," American Society for Testing
and Materials, Philadelphia, PA, p. 76, 1980.
8. Burke, J.A., "Gas Chromatography for Pesticide Residue Analysis;
Some Practical Aspects," Journal of the Association of Official
Analytical Chemists, 48, 1037 (1965).
9. Glaser, J.A. et al, "Trace Analysis for Wastewaters", Environmental
Science and Technology, 15, 1426 (1981).
46
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TABLE 1. CHROMATOGRAPHIC CONDITIONS AND
METHOD DETECTION LIMITS
Parameter
Amobam
Busan 40
Busan 45
EXD
Ferbam
KN-Methyl
Metham
Nabam
Nabonate
Na DMDTC
Thiram
Zineb
Ziram
Retention Time (Min)(a)
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
MDL(ug/L)
1.1
4.4
1.3
5.2
2.9
2.7
3.1
1.6
0.9
2.8
2.2
4.1
4.6
(a) Retention time of CS2 under the following conditions:
Carbopack C (80/100 mesh) coated with 0.1% SP-1000
packed in a 180 cm long x 2 mm ID glass column with
helium carrier gas at a flow rate of 25 mL/min.
Column temperature held at 70°C for 3 minutes,
programmed at 20°C/min to 120°C, and then held at 120°C
for 5 minutes. Column effluent is vented from the
Hall detector after elution of C$2 from the column.
Injector temperature and detector temperatures are
200°C. The Hall detector is operated in the sulfur
mode following manufacturer's specifications.
47
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TABLE 2. SINGLE LABORATORY ACCURACY AND PRECISION
Parameter
Amobam
Busan 40
Busan 85
EXD
Ferbam
KN Methyl
Me than
Nabam
Nabonate
NaDMDTC
Th i ram
Zineb
Ziram
(a) 1 -
Sample
Type(a)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Wastewater
Background
ug/L
4.6
4.6
6.6
6.6
5.9
5.9
4.5
4.5
5.2
5.2 '
5.4
5.4
6.2
6.2
4.8
4.8
6.1
6.1
5.4
5.4
4.5
4.5
5.2
5.2
5.7
5.7
Spike Mean
vg/L Recovery, %
50
500
50
500
50
500
50
500
50
• 500
50
500
50
500
50
500
50
500
50
500
50
500
50
500
50
500
from a manufacturer of a
90
93
110
100
110
100
71
76
94
no
90
89
no
84
62
65
66
56
no
no
89
82
87
86
100
95
Standard
Deviation
7.8
8.7
7.2
6.1
5.5
2.0
7.5
2.4
4.8
1.8
6.1
2.5
5.2
5.9
6.6
13
11
12
2.5
4.2
2.9
3.4
3.4
9.4
12
19
dithiocarbamate diluted
Number of
Replicates
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
1000:1
with Columbus POTW secondary effluent.
48
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cs,
1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00
Retention Time, Min.
FIGURE 1. GC-HALL CHROMATOGRAM OF 0.1 NG OF C$2
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