Method 614.1

The Determination of

Organophosphorus Pesticides in

Municipal and Industrial

Wastewater
Method 614.1

The Determination of Organophosphorus Pesticides in Municipal and

Industrial Wastewater

1. SCOPE AND APPLICATION

1.1 This method covers the determination of certain organophosphorus pesticides in

municipal and industrial wastewater. The following parameters may be determined by

this method.

Parameter STORET No. CAS No.

Dioxathion 78-34-2

EPN 2104-64-5

Ethion 39398 563-12-2

Terbufos 13071-79-9

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 nitrogen/phosphorus detector

equal to 5 times the gas chromatographic (GC) background noise assuming a 1.0-mL

final extract volume of a 1-L reagent water sample and an injection of 5 μL. The EDL

for a specific wastewater may be different depending on the nature of interferences in

the sample matrix.

1.3 This is a gas chromatographic (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 Organophosphorus pesticides are removed from the sample matrix by extraction with

15% methylene chloride in hexane. 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 a nitrogen/phosphorus-specific detector.

2.2 Confirmatory analysis by GC/MS is recommended when a new or undefined sample

type is being analyzed if the concentration is adequate for such determination.
Method 614-1

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

conditions 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. Clean all glassware as soon as possible 1

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 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 coextracted 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 for the 2-4

information of the analyst.

5. APPARATUS AND EQUIPMENT

5.1 Sample containers: Narrow-mouth glass bottles, 1-L or 1-quart volume, equipped with

polytetrafluoroethylene (PTFE)-lined screw-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 at 400°C for 1 hour. After cooling, rinse the

cap liners with hexane, seal the bottles, and store in a dust-free environment.
Method 614-1

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) and

two-ball micro (Kontes K-569001-0219 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 3% OV-225 on

Supelcoport (100/120 mesh) or equivalent.

5.3.1.2 Column 2: 120 cm long by 2 mm ID, Pyrex glass, packed with R

1.5% OV-17/1.95 % QF-1 on Gas Chrom Q, 80/100 mesh or equivalent.

5.3.1.3 Column 1 was used to develop the accuracy and precision statements in

Section 12. Guidelines for the use of alternative column packings are

provided in Section 10.3.1.

5.3.1.4 Detector: nitrogen/phosphorus. This detector has proven effective in the

analysis of wastewaters for the parameters listed in the scope and was

used to develop the method performance statements in Section 12.

Guidelines for the use of alternative detectors are provided in

Section 10.3.1.

5.4 Chromatographic column: 300 mm long by 10 mm ID Chromaflex, equipped with

coarse-fitted bottom plate and PTFE stopcock. (Kontes K-420540-0213 or equivalent).

5.5 Drying column: Approximately 400 mm long by 20 mm ID borosilicate glass, equipped

with coarse-fitted bottom plate.
Method 614-1

5.6 Miscellaneous.

5.6.1 Balance: Analytical, capable of accurately weighing to the nearest 0.0001 g.

5.6.2 Separatory funnel: 2-L, equipped with PTFE stopcock.

5.6.3 Water bath: Heated with concentric ring cover, capable of temperature control

(±2°C). 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

perform a Soxhlet extraction with methylene chloride.

6. REAGENTS AND CONSUMABLE MATERIALS

6.1 Reagents.

6.1.1 Acetone, hexane, and methylene chloride: Demonstrated to be free of analytes.

6.1.2 Silica gel: Woelm 70-230 mesh. Activate approximately 100 g of silica gel at

200°C for 6 hours in a tared 500-mL Erlenmeyer flask with ground-glass stopper.

Allow to cool to room temperature, reweigh, and determine the weight of

activated silica gel. Deactivate by adding 3% by weight of distilled water.

Restopper the flask, and shake on a wrist-action shaker for at least one hour.

Allow to equilibrate for 3 or more hours at room temperature.

6.1.3 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.

6.1.4 Sodium hydroxide (NaOH) solution (10N): Dissolve 40 g NaOH in reagent water

and dilute to 100 mL.

6.1.5 Sodium sulfate: Granular, anhydrous. Condition by heating at 400°C for 4 hours

in a shallow tray.

6.1.6 Sulfuric acid (H SO ) solution (1+1): Add measured volume of concentrated 2 4

H SO to equal volume of reagent water. 2 4

6.2 Standard stock solutions (1.00 μg/μL): 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 g of pure

material. Dissolve the material in hexane 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.
Method 614-1

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 should be followed, except that the bottle must not be 5

prewashed with sample before collection.

7.2 The samples must be iced or refrigerated at 4°C from the time of collection until

extraction.

7.3 Chemical preservatives should not be used in the field unless more than 24 hours will

elapse before delivery to the laboratory. If the samples will not be extracted within

48 hours of collection, the sample should be adjusted to a pH range of 6.0 to 8.0 with

sodium hydroxide or sulfuric acid.

7.4 All samples must be extracted within 7 days and completely 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 estimated detection limit (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 μg/L, and a sample expected to contain approximately

5 μg/L is analyzed, solutions of standards should be prepared at concentrations

of 0.3 μg/L, 5 μg/L, and 10 μg/L for the particular analyte.

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.
Method 614-1

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.

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 1-L 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 standard 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 6.2, prepare a laboratory control standard

concentrate that contains each analyte of interest at a concentration of

2 μg/mL in acetone or other suitable solvent.7

9.2.1.2 Laboratory control standard: Using a pipette, add 1.00 mL of the

laboratory control standard concentrate to a 1-L 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 (P ) with the equation: i

Equation 1

where

S = Analytical results from the laboratory control standard, in μg/L i

T = Known concentration of the spike, in μg/L i

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.
Method 614-1

9.3.1 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.

9.3.2 For each analyte in each duplicate pair, calculate the relative range (RR ) with the 7

i

equation:

Equation 2

where

R = Absolute difference between the duplicate measurements X and X , in μg/L i 1 2

X = Average concentration found , in μg/L i

9.3.3 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. PROCEDURE

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-L 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 15% methylene chloride/hexane 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.

10.1.3 Add an additional 60-mL volume of 15% methylene chloride/hexane to the

sample bottle and complete the extraction procedure a second time, combining the

extracts in the Erlenmeyer flask.
Method 614-1

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 it 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 (80 to 85°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 1 mL, remove the K-D apparatus and allow it

to drain and cool for at least 10 minutes. Remove the Snyder column and rinse

the flask and its lower joint into the concentrator tube with 1 to 2 mL of hexane.

A 5-mL syringe is recommended for this operation. If the extract requires

cleanup, proceed to Section 10.2 (cleanup and separation). If cleanup has been

performed or if the extract does not require cleanup, proceed with Section 10.1.6.

10.1.6 Add a clean boiling chip to the concentrator tube. Attach a two-ball micro-Snyder

column. Prewet the micro-Snyder column by adding about 0.5 mL of hexane to

the top. Place this micro K-D apparatus on a steaming-water bath (80 to 85°C)

so that the concentrator tube is partially immersed in the hot water. Adjust the

vertical position of the apparatus and water temperature as required to complete

the concentration in 5 to 10 minutes. At the proper rate of distillation, the balls

will actively chatter but the chambers will not flood. When the apparent volume

of liquid reaches 0.5 mL, remove the K-D apparatus and allow it to drain and cool

for at least 10 minutes. Remove the micro-Snyder column and rinse its lower

joint into the concentrator tube with a small volume of hexane. Adjust the final

volume to 1.0 mL or to a volume suitable for cleanup or gas chromatography, and

stopper the concentrator tube; store refrigerated if further processing will not be

performed immediately. If the extracts will be stored longer than two days, they

should be transferred to PTFE-sealed screw-cap bottles. Proceed with gas

chromatographic analysis.

10.1.7 Determine the original sample volume by refilling the sample bottle to the mark

and transferring the liquid to a 1000-mL graduated cylinder. Record the sample

volume to the nearest 5 mL.

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 silica gel procedure

allows for a select fractionation of the compounds and will eliminate non-polar

materials. 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
Method 614-1

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 Prepare silica gel columns using a glass column 200 mm long by 10 mm ID.

Rinse column with hexane. Add approximately 50 mL of hexane to the empty

column. Add 3.5 grams of 3% deactivated silica gel. Pack by rotating slowly to

release air bubbles. Top with 1.5 cm of Na SO . Drain hexane to the top of 2 4

Na SO layer. 2 4

10.2.3 Just prior to exposure of the sodium sulfate layer to the air, transfer the sample

extract onto the column using an additional 2 mL of hexane to complete the

transfer.

10.2.4 Just prior to exposure of the sodium sulfate layer to the air, add 30 mL of 6%

methylene chloride/hexane and continue the elution of the column, collecting the

eluate in a 500-mL K-D flask equipped with a 10-mL concentration tube. Elution

of the column should be at a rate of about 2 mL per minute. Add 50 mL of

hexane to the flask and concentrate the collected fraction by the standard

technique prescribed in Sections 10.1.5 and 10.1.6.

10.2.5 Continue the elution of the column according to the scheme outlined in Table 3.

The elution of the compounds may vary with different sample matrices.

10.2.6 Analyze the fractions by gas chromatography.

10.3 Gas chromatographic analysis.

10.3.1 Recommended columns and detector for the gas chromatography 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 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% and data quality comparable to

Table 2 are achieved.

10.3.2 Inject 2 to 5 μL of the sample extract using the solvent-flush technique. Record 8

the volume injected to the nearest 0.05 μL, the total extract volume, 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.
Method 614-1

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 micrograms

per liter with the equation:

Equation 3

where

A = Amount of material injected, in ng

V = Volume of extract injected, in μL i

V = Volume of total extract, in μL t

V = Volume of water extracted, in mL s

11.2 Report the results for the unknown samples in microgram per liter. Round off the results

to the nearest 0.1 μg/L or two significant figures.

12. METHOD PERFORMANCE

12.1 Estimated detection limits (EDL) and associated chromatographic conditions are listed

in Table 1. The detection limits were calculated from the minimum detectable response 9

of the N/P detector equal to 5 times the GC background noise, assuming a 1.0 mL final

extract volume of a 1-L sample and a GC injection of 5 μL.

12.2 Single laboratory accuracy and precision studies were conducted by ESE, using spiked 6

relevant industrial wastewater samples. The results of these studies are presented in

Table 2.

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 compounds of interest. 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.
Method 614-1

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 625.10

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.11

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 ng 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% relative abundance

in the mass spectrum of the standard must be present in the mass spectrum of the

sample with agreement to ±10%. For example, if the relative abundance of an ion

is 30% 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%.

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.

13.6 Should these MS procedures fail to provide satisfactory results, additional steps may be

taken before reanalysis. These may include the use of alternative packed or capillary GC

columns or additional cleanup.
Method 614-1

References

1. 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.

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.

7. "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.

8. Burke, J.A. "Gas Chromatography for Pesticide Residue Analysis; Some Practical

Aspects," Journal of the Association of Official Analytical Chemists, 48, 1037 (1965T)

9. "Evaluation of Ten Pesticide Methods," U.S. Environmental Protection Agency, Contract

No. 68-03-1760, Task No. 11, U.S. Environmental Monitoring and Support Laboratory,

Cincinnati, Ohio 45268.

10. "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.

11. Eichelberger, J.W., Harris, L.E., and Budde, W.L. Analytical Chemistry, 46, 1912 (1975).
Method 614-1

Table 1. Gas Chromatography of Organophosphorus Pesticides

Retention Time (min) Detection Limit

Parameter Column 1 Column 2 (μg/L)

Terbufos 1.41 1.9 .004

Dioxathion 2.3 2.3 .01

Ethion 8.3 6.4 0.1

EPN 13.3 8.3 0.2

Column 1: 180 cm long by 2 mm ID, glass, packed with 3% OV-225 on 100/120 Supelcoport;

nitrogen carrier gas at a flow rate of 50 mL/min. Column temperature is 200°C for 2 minutes,

then programmed at 5°/min. to 240°C and held for 5 minutes.

Column 2: 120 cm long by 2 mm ID, Pyrex glass, packed with 1.5% OC-17/1.95% QF-1 on R

80/100 mesh Gas Chrom Q or equivalent; nitrogen carrier gas at a flow rate of 30 mL/min.

Column temperature is 180°C for 2 minutes, then programmed at 8°/min. to 250°C and held for

4 minutes.

Table 2. Single-Laboratory Accuracy and Precision

Parameter Type* (μg/L) Replicates Recovery Deviation (%)

Matrix Spike Range Number of Average Percent Standard

Dioxathion 1 1,978.0 7 94.3 19.9

1 19.8 7 99.0 27.5

EPN 1 1,293.0 7 96.1 6.1

Ethion 1 1,788.0 7 89.2 4.5

Terbufos 1 15.1 7 101.0 12.4

1 1,508.0 7 95.0 3.4

*1 = Combined industrial wastewaters
Method 614-1

Table 3. Silica Gel Cleanup of Organophosphorus Pesticides

Percent Recoveries

Silica Gel Fraction* Terbufos Dioxathion Ethion EPN

1 0 0 0.8 0

2 0 0 1.9 0

3 93.0 35.1 94.9 46.4

4 0 52.7 3.0 56.0

Total Percent Recoveries 93.0 87.8 101 102

*Fraction 1 = 30 mL 6% MeCl in hexane 2

 Fraction 2 = 30 mL 15% MeCl in hexane 2

 Fraction 3 = 30 mL 50% MeCl in hexane 2

 Fraction 4 = 30 mL 100% MeCl2
Method 614-1
Method 614-1