Identification and 

Measurement of 

Chlorinated Organic 

Pesticides in Water by 

Electron-Capture 

Gas Chromatography

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1817-B
Identification and 

Measurement of 

Chlorinated Organic 

Pesticides in Water by 

Electron-Capture 

Gas Chromatography

By WILLIAM L. LAMAR, DONALD F. GOERLITZ, and LfiROY M. LAW

ORGANIC SUBSTANCES IN WATER

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1817-B

A convenient and sensitive method for 

monitoring chlorinated organic 

pesticides in water

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1965
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 15 cents (paper cover)
CONTENTS

Page

Abstract.._----__-_--_-_-______--_----_--_-_----_--__--------_-- Bl

Introduction-__-____--_-_---_____---_--_---__-_--------_--------__ 1

Collection and handling of samples.-_-----_-__--__-------_-_---__--- 3

Electron-capture gas chromatographic method-___..---_---,______.___ 4

Apparatus.-__-__---_-----_------------_-------_-_-------__-__ 4

Reagents-_-____----_---______-_---_-_-_-_-_-_-___-_---_------ 4

Procedure for analysis__._-_-_---____________-____-______-__-. 5

Interferences....--_-__--------__-_---_-----_---_---------__------- 6

Results and summary-___-----_-___---_--_-_--_-_-_-_-_-_-------_-_ 8

Ref eren ces----__-------------------_-_-------------------_-------- 11

TABLES

Page 

TABLE 1. Electron-capture gas chromatographic data for pesticide

standards.-------_-_---_-------_-___-_-_-----_-____--_ B6

2. Recovery of pesticides from distilled water after addition as an

emulsion __-_-----_-_---_-._-__-.--____---_-----_-_-.-_ 9

3. Recovery of pesticides from selected water samples after addition as an emulsion_.---_---------__-----_----._-_-_---- 10

4. Electron-capture gas chromatographic analysis of chlorinated

pesticides in unfiltered surface water__-.-_--_--_-___-_-. 11

in
ORGANIC SUBSTANCES IN WATER

IDENTIFICATION AND MEASUREMENT OF CHLORINATED 

ORGANIC PESTICIDES IN WATER BY ELECTRONCAPTURE GAS CHROMATOGRAPHY

By WILLIAM L. LAMAK, DONALD F. GOEELITZ, and LsRoY M. LAW

ABSTRACT

Pesticides, in minute quantities, may affect the regimen of streams, and because they may concentrate in sediments, aquatic organisms, and edible aquatic 

foods, their detection and their measurement in the parts-per-trillion range are 

considered essential.

In 1964 the U.S. Geological Survey at Menlo Park, Calif., began rese°rch on 

methods for monitoring pesticides in water. Two systems were selected electron-capture gas chromatography and microcoulometric-titration gas chromatography. Studies on these systems are now in progress. This report provides 

current information on the development and application of an electron-capture 

gas chromatographic procedure. This method is a convenient and eytremely 

sensitive procedure for the detection and measurement of organic pesticides 

having high electron affinities, notably the chlorinated organic pesticides. The 

electron-affinity detector is extremely sensitive to these substances bnt it is 

not as sensitive to many other compounds. By this method, the chlorinated 

organic pesticide may be determined on a sample of convenient size in concentrations as low as the parts-per-trillion range. To insure greater accuracy in 

the identifications, the pesticides reported were separated and identified by 

their retention times on two different types of gas chromatographic colnmns.

INTRODUCTION

The term "pesticide" is exercised to cover a broad class of toxicants 

that are used to control insects, mites, fungi, weeds, aquatic plants, 

and undesirable animals. More specific designations include such 

terms as insecticides, miticides, nematocides, fungicides, rodenticides, 

herbicides, weedkillers, and defoliants.

Synthetic organic pesticides have introduced a far-reaching technological advance in the control of pests. Although the organic 

compound DDT (dichlorodiphenyltrichloroethane) was first synthesized in 1874, its insecticidal properties were not discovered until 1939. 

By 1955, however, more than 100 synthetic organic insecticides were

Pi
B2 ORGANIC SUBSTANCES IN WATER

in commercial use (Nicholson, 1959). As of June 1962, almost 500 

chemical compounds incorporated in more than 54,000 formulations 

were available for use in the United States (President's Science Advisory Committee, 1963). Johnson, Krog, and Poland (1963) reported that in 1962 sales of chemical pesticides at the consumer level 

reached a record of 1.04 billion dollars and predicted that by 1975 the 

sales of these toxicants could well reach 2 billion dollar?. The predominant trend toward synthetic organic pesticides is expected to 

continue, especially toward more selective pesticides to control a 

"target" pest or class of pests and (or) to regulate certain environmental conditions. When pests develop a tolerance to one toxicant, 

more selective or more toxic poisons are formulated.

Some organic pesticides maintain a residual toxicity for years, 

whereas others promptly degrade after application. For example, 

chlorinated hydrocarbon pesticides are generally more persistent and 

more toxic to fish than the organic phosphorus compounds The high 

stability of DDT contributes to its usefulness as an effective insecticide, but this property introduces an environmental contamination 

problem. After a study to determine the persistence of DDT residues in soils of forest stands which had been heavily sprayed, Woodwell and Martin (1964) reported that DDT residues do accumulate 

and persist for substantial periods, probably longer than the 10 years 

previously estimated (Woodwell, 1961). The study by Woodwell 

(1961) indicated that the ortho-para isomer of DDT is approximately 

10 times as persistent as the para-para isomer.

Adequate and convenient identification and measurement of pesticides in water involve complex problems to which there have been 

many approaches. Procedures have included visible, ultraviolet, and 

infrared spectrophotometry, paper, column, thin-layer and gas chromatography, and combinations of these tools (Dugan and others, 1963; 

Goodenkauf and Erdei, 1964; Gutenmann and Lisk, 1964; Hindin and 

others, 1962; Kalin and Wayman, 1964; Nicholson and others, 1964; 

Eyckman and others, 1964; Skrinde and others, 1962; and Teasley 

and Cox, 1963). Eosen and Middleton (1959) reported s, procedure 

for monitoring chlorinated insecticides in water using a combination 

of carbon-adsorption sampling, adsorption chromatography, and infrared spectrophotometry. The carbon-adsorption metl id, which 

involves sample volumes as large as 5,000 gallons, has br^n applied 

with various techniques for the analysis of pesticides in wHer (Breidenbach and Lichtenberg, 1963). However, because the carbon-adsorption method is time-consuming and because recovery tends to be 

low and (or) quite conditional (Goodenkauf and Erdei, 1964; Grzenda 

and others, 1964; Hoak, 1964; Ryckman and others, 1964; Teasley and
CHLORINATED ORGANIC PESTICIDES B8

Cox, 1963; Weber and Morris, 1963a, 1963b; and Wolf, 1963), attention is being given to more direct and highly sensitive techniques which 

can be performed with a sample of convenient size.

Lovelock and Lipsky (1960) described a sensitive and seb-ctive 

device called an electron-affinity or electron-capture detector. This 

device, used to detect components as they emerge from a gas chroma - 

tographic column, makes possible the selective detection of minute 

amounts of compounds which have high electron affinities. Inasmuch as chlorinated organic pesticides have high electron affinities, 

they may be separated and measured in the presence of compounds 

having low electron affinities. For example, the electron-capturing 

potential of many of the chlorinated organic pesticides is a million 

or more times greater than that of hexane.

Electron-capture gas chromatographic systems are now readily 

available and are being increasingly used for the measurement of 

extremely low concentrations. Development of more advanced instrumentation and techniques of electron-affinity detection and measurement is in progress (Lovelock, 1963). No one method will be 

adequate because of the large number of different types of pesticides 

and also because of the different conditions under which they are 

present in water. However, the development of electron-capturing 

procedures for monitoring organic pesticides in water is particularly 

important because chlorinated and other pesticides with high electroncapturing potentials have the greatest tonnage-use.

In 1964, the U.S. Geological Survey at Menlo Park, Calif., began 

research on methods for monitoring pesticides in water. Two systems 

were selected electron-capture gas chromatography and microcoulometric-titration gas chromatography. These studies &YV continuing. This report provides current information on advantages, 

disadvantages, interferences, and application of an electron-capture 

gas chromatographic procedure.

COLLECTION AND HANDLING OF SAMPLES

The samples are collected in 4-liter glass bottles which have been 

carefully cleaned and then heat-treated at 300°C overnight to destroy 

any trace of organic matter (see section on "Interferences"). Tc avoid 

airborne contamination, the sample bottle should be stoppered 

promptly. However, it is important to prevent contact of the sample 

with rubber, cork, and most plastic (Teflon, a fluorocarbon resin, is 

satisfactory). Rubber or cork stoppers which have been carefully 

wrapped with a double layer of organic-free tin or aluminum foil 

are satisfactory. Care must be taken when stoppering the bottle 

that the foil covering is not ruptured. The sample should not be 

transferred from one container to another.
B4 ORGANIC SUBSTANCES IN WATER

ELECTRON-CAPTURE GAS CHROMATOGRAPHIC

METHOD

APPARATUS

The essential experimental functions isolation of the chlorinated 

pesticides and their determination by electron-capture gas chromatography are performed with the following apparatus:

Gas chromatograph: Aerograph Hy-FI, Wilkens Model 610-C, 

manual temperature-programming gas chromatograph with electroncapture detector and differential flow controller.

Gas chromatographio oven: Aerograph Hy-FI, Wilkens Model 

550, equipped with electron-capture detector, differential flow controller, and detector transfer switch. This additional even permits 

use of two different gas chromatographic columns without cooling the 

oven to change columns.

Gas chromatographic columns: Two columns are used: (1) 

Dow-11, silicone grease coated 5 percent by weight on 60-80 mesh 

Chromasorb W (nonacid washed) packed into a 1.5-mm-ID, 3-mmOD heat-resistant glass column, 5 feet long. (2) QF-1 (also designated FS-1265), fluorinated silicone coated 5 percent by weight on 

60-80 mesh Chromosorb W (nonacid washed) packed into a 1.5-mmID, 3-mm-OD heat-resistant glass column, 5 feet long.

Recorder: Honeywell Brown Electronik, class 15, 1-riv full-scale 

response, 1-second pen speed, with a Disc chart integrator.

Sand bath: Tecam fluidized sand bath. A steam bath may be used 

in place of the sand bath.

Concentrating apparatus: Kuderna-Danish concentrator, 250-ml 

capacity.

BEAGENTS

Anhydrous sodium sulfate: Reagent grade, heated at 400 °C 

overnight and stored in a glass-stoppered bottle. The crystals must 

be free of electron-capturing material; test by rinsing them with 

hexane and check the rinsing with the electron-capture gas 

chromatograph.

n-Hexane: Reagent grade, redistilled from a packed column after 

being refluxed over bright sodium ribbon for 8 hours and tested to 

insure that it does not contain significant amounts of interfering 

electron-capturing components when concentrated 10 times and analyzed as a reagent blank.

Distilled water: See section on "Interferences" for precautions to 

be observed for preparing organic-free distilled water.
CHLORINATED ORGANIC PESTICIDES B5 

PROCEDURE FOR ANALYSIS

All glassware, except the volumetric, is heat-treated at 300°C overnight to avoid organic contamination. The volumetric glassware is 

cleaned in the conventional manner with cleaning solution (sodium 

dichromate in concentrated sulfuric acid). Before they are used, all 

reagents and glassware are checked for contamination by electroncapture gas chromatography.

1. Extract the pesticides with hexane in such a manner that the water, 

sediment, and container itself are exposed to the solvent; the 

following technique is recommended: Pour part of the water 

sample into a 1-liter separatory funnel and shake with 25 ml of 

hexane for 1 minute. Allow the contents to separate for at least 

10 minutes and collect the aqueous layer in another 4-liter bottle.

2. Repeat this procedure until all the water has been extracted with 

the same 25 ml of hexane. If the hexane layer becomes partly 

emulsified, add distilled water to help break the emulsion.

3. Pour the hexane layer from the top of the separatory funnel into a 

125-ml Erlenmeyer flask containing 0.5 g of anhydrous sodium 

sulfate, Allow the sample bottle to drain into the separatory 

funnel for at least 5 minutes. Einse the bottle with 25 ml of 

hexane which is then also poured into the separatory funnel. 

Several washings made with some of the previously extracted 

water sample will help transfer the hexane to the separatory 

funnel.

4. Extract the water a second time with the same 25 ml of hexane used 

to rinse the sample bottle after the first extraction is completed. 

Collect the aqueous layer in the original sample bottle, and combine the second hexane extract with the first extract in the 125-ml 

Erlenmeyer flask. Extract the water a third time with another 

25 ml of hexane and add this extract to the first two extracts already in the Erlenmeyer flask. Discard the extracted water after 

its volume has been recorded to three significant figures.

5. Decant the combined extracts from the sodium sulfate into a 

Kuderna-Danish concentrating apparatus. Now remove most of 

the hexane by heating on a fluidized sand bath at 100°C. Transfer the hexane solution quantitatively with a disposable pipette 

to a 10.00-ml volumetric flask. Bring the solution to volume with 

hexane and then add about 50 mg of anhydrous sodium sulfate. 

Mix the contents thoroughly.

6. Take 5-/J (microliter) aliquots of the sample with a microliter 

syringe and inject them into the gas chromatograph. The injections are made on both Dow-11 and QF-1 columns to facilitate 

identification through the different partitioning effects of tl °- two

7'72-45c
B6 ORGANIC SUBSTANCES IN WATER

liquid substrates. The operating conditions for both columns 

are the same. The glass-lined injection ports are Hid at 210°- 

220°C, and the columns are heated at 185°±5°C. Record the 

exact temperatures at the time of analysis. The nitrogen carrier 

gas, which is dried by a Molecular Sieve (Linde type 13X), is 

regulated at 40 ml per minute by differential flow controllers. 

7. Because the electron-affinity potential of each pesticide may be 

different, standardization curves must be determined and retained 

for quantitative analysis. Quantitative and qualitative pesticide 

standards are injected on the same day the pesticide samples are 

analyzed to aid in identification and to provide correction, as 

necessary, for day-to-day fluctuations in the instrument. Retention times are recorded and are summarized in table 1. Relative 

retention times (the ratio of the retention time of th°, particular 

pesticide to that of aldrin) are also given.

TABLE 1. Electron-capture gas chromatographic data for pesticide standards

Pesticide

Dieldrin

o, p'-DDT _ _

p, p'-DDT

Endrin ...

Heptachlor

Tjindanf

Dow-11 column

Retention 

time 

(minutes)

4.74 

9.76 

12.90 

16.50 

10.80 

3.74 

6.16 

2.18

Relative 

retention 

time

1.00 

2.06 

2.72 

3.48 

2.28 

.79 

1.30 

.46

QF-1 columi

Retention 

time 

(minutes)

1.58 

4.84 

4.16 

6.14 

5.58 

1.40 

3.06 

1.32

Relative 

retention 

time

1.00 

3.06 

2.63 

3.89 

3.53 

.89 

1.94 

.84

Response 

(mv-sec 

per 10-iig)

94

97

27

70 

71 

99 

93

8. The pesticides are identified on two different types of gas chromatographic columns by comparing their relative retention times. 

The initial identifications are made on a Dow-11 column and 

the confirmations are made on a QF-1 column. If a closely 

eluting component interferes with the identification, then, to 

confirm the identification, a small amount of the pesticide suspected to be present should be added to the sample to be injected 

into the columns. The injection consists of a measured amount 

of the pesticide standard drawn into a microliter syrmge already 

charged with an aliquot of the sample extract.

INTERFERENCES

The experimental studies showed that lindane present in the injected 

sample in amounts as low as 0.1 picogram (1 picogram=10~12 gram) 

can be readily detected and measured. The degree of sensitivity varies 

with the electron affinity of the particular compound aid also from
CHLORINATED ORGANIC PESTICIDES B7

one instrument to another. High sensitivity requires meticulous1 laboratory techniques and high-purity reagents. Trace contamination by 

compounds with high electron-affinity potentials should be avoided, 

but other contaminants do not seriously affect the results.

When this investigation started, all glassware in the laboratory was 

discovered to be contaminated extensively with interfering organic 

compounds. The contamination was largely due to distilled water 

used for rinsing the glassware. The distilled water was obtained 

from a high-purity still that had no provision for removing organic 

material from the feedwater, but most of the organic contamination 

actually was coming from the valves, gaskets, connections, piping, and 

the storage system, and possibly from the pump used to pump the 

water to the storage tank. This contamination may be remedied by 

collecting the distilled water directly from the condenser exit. Depending on the quality of the feedwater, it may be necessary to use 

a high-purity still with an organic remover on the feedwater.

A more convenient and satisfactory distilled-water system is a 

gravity one that consists of a high-purity still with an organic remover 

(activated carbon) on the feedwater, a tin-lined or tin-silver-lined 

storage tank having an ultraviolet lamp, and tin-lined piping, v?,lves, 

and connections. If some plastic must be used in the system. Teflon, 

a fluorocarbon resin, is satisfactory. High-purity (organic-free) 

distilled water may be also obtained by redistilling good quality distilled water over alkaline permanganate in an all-glass system.

Each laboratory will have to insure that the sample bottles and 

all glassware used in the analysis are free of electron-capturing contaminants. Rinsing the glassware with solvents will remove organic 

contaminants, but the effectiveness of this removal apparently varies 

inversely with the degree of adsorption. For example, contamir ated 

glassware was rinsed with hexane until the analysis of these rinsings 

indicated no contamination, but this hexane-rinsed glassware again 

contaminated hexane which remained in it overnight. The authors 

found that heat-treating the glassware (including sample bottles but 

not volumetric glassware) at 300° C overnight is the most convenient 

way to avoid contamination from organic matter. As a further precaution, the glassware should be solvent-rinsed and checked by 

electron-capture gas chromatography prior to use.

Reagents as presently obtained on the market, including chromatoquality reagents, are usually not pure enough for use in electroncapture analysis. ACS-grade or chromatoquality hexane can be further purified by refluxing it over bright sodium (freshly prepared 

sodium ribbon). However, the quality of the hexane solvent may vary 

from bottle to bottle, and therefore this treatment is not always 

adequate.
B8 ORGANIC SUBSTANCES IN WATER

Another possible significant source of contamination, which might 

be termed the "screw-cap effect," is the plastic screw caps used on 

sample bottles and reagent bottles. Even if the plastic cap itself does 

not cause contamination, the liner on the cap may do so. For example, 

during the investigations the anhydrous sodium sulf ate used in drying 

the solvent was found to be contaminated. In tracing the source, it 

was established that the screw-cap liner had contaminated the sodium 

sulf ate. Impurities from this source can be avoided by heat-treating 

the sodium sulf ate at 400° C overnight and by storing it in an all-glass 

container.

High-purity nitrogen carrier gas is required for direct-current electron-capture detectors. This gas should be filtered and dry. Particular attention should be given to the efficiency of the drying agent 

because an exhausted drier will allow the passage of water, thus reducing the standing current.

RESULTS AND SUMMARY

The experimental results obtained by the use of this method cover a 

variety of waters. These include waters from streams that were 

analyzed for chlorinated organic pesticides and both distilled water 

and stream samples to which the pesticides were added for recovery 

tests.

In the recovery studies, two techniques of introducing the pesticides 

into the water were investigated hexane solutions and emulsion suspension :

1. Addition of pesticides from nonaqueous solution such as a hexane 

solution, is a very convenient technique that is frequently used by 

many workers in this field, but investigations indicated that this 

technique is not acceptable because the recovery of the chlorinated 

organic pesticides after they were added to distilled water was low, 

ranging from 54 to 87 percent. Many chlorinated hydrocarbon 

pesticides are not very soluble in water. A true solution is probably 

not immediately achieved when they are added to water in hexane 

solvent. The suspension assumed to take place is not uniform and, 

even in samples having concentrations in the parts-per-trillion range, 

the rate of solution is not rapid enough. Handling and processing 

nonuniform suspensions also introduce problems.

2. Because the hexane-solution technique did not provide satisfactory 

recovery, a procedure using emulsifiable pesticide concentrates was 

developed. Microliter quantities of emulsifiable concentrates of 

aldrin, DDT, dieldrin, endrin, heptachlor, and lindar e were added 

to distilled water. Portions of each suspension were serially diluted, and the concentration of the pesticide in the final diluted
CHLORINATED ORGANIC PESTICIDES B9

suspension was determined by gas chromatography; vigorous mixing prior to sampling obviated measurable phase separation. Appropriate amounts of the pesticides were added to 4 liters of distilled water. Recovery experiments were performed on these prepared samples using the developed gas chromatographic method. 

These results, expressed in nanograms (1 nanogram==10-9gram), are 

shown in table 2. From these data, it is concluded that addition of 

pesticides to water as standardized-emulsion suspensions is 

acceptable.

TABLE 2. Recovery of pesticides from distilled water after addition as an

emulsion

Test

1 .... _ . _ ....

2... ___ ..... __ ....

3. _ ....... _ . ___

4... _ ..... _ .......

5.... . . _____ .

Pesticide

Dieldrin.. _____ . ________

Aldrin... _ _ _____ .

Dieldrin--- 

Aldrin.-..-.. _ ............. _ .....

Dieldrin... __ ~ 

DDTL ..... .. __ ................

DDT L _ .

Quantity 

added 

(nanograms)

1,100 

940 

880 

1,210

1,100 

940 

880 

1,210

1,274 

1,156 

127 

1,401

5,100

3,773 

980

Recovered

Nanograms

980 

960 

735 

1,225

970 

910 

720 

1,150

1,320 

1,200 

130 

1,600

5,000

3,850 

1,000

Percent

89 

102 

84 

101

88 

97 

82 

95

104 

104 

102 

114

98

102 

102

i Summation of o,p'-DDT and p,p'-DDT.

To study the reliability of the gas chromatographic method on unfiltered surface-water samples and to document the stability of pesticides with respect to time, additional recovery experiments were performed. Three samples from each of the different streams were 

collected in 4-liter bottles. Known amounts of the standard izedpesticide emulsion were added to two of the samples of water; the 

remaining sample of water was used as the blank. All three samples 

of water were analyzed by the gas chromatographic procedure; the 

blank and one sample containing the added pesticides were analyzed 

immediately, but the other sample containing the added pesticides 

was analyzed 30 days later to determine the stability of the pesticides.

The data on the recovery of the pesticides are shown in table 3. All 

the results are satisfactory except that for heptachlor recovered 30 

days later. Whereas the recovery of the heptachlor immediately after 

addition was satisfactory, no heptachlor nor its conversion product, 

heptachlor epoxide, was found 30 days later. (Bowman and others, 

1964, reported the conversion of heptachlor to heptachlor epoxide as 

a metabolite in mosquito larvae, but this conversion did not occur in 

the aqueous suspensions.)
BIO ORGANIC SUBSTANCES IN WATER

TABLE 3. Recovery of pesticides from selected water samples after addition as

an emulsion

Source

Yuma Main Canal at Yuma, Ariz. (water 

diverted from Colorado River at Imperial Dam).

Pesticide

DDTi. -

Dieldrin......

Heptaehlor.,..

DDTi. .

Dieldrin ......

Heptachlor....

DDTi.. ......

Dieldrin.... ..

Endrin _ . __

Heptachlor ....

Quantity 

added (nanograms)

296 

1,159 

229 

289 

408 

174

296 

1,159 

229 

289 

408 

174

296 

1,159 

229 

289 

408 

174

Recovered

Immediately

Nanograms

280 

1,320 

236 

224 

500 

182

316 

1,378 

247 

237 

490 

198

300 

1,220 

234 

234

500 

178

Percent

95 

114 

1C* 

78 

15.3 

1C5

1C7 1]° 

1C8 

?2 

120 

1H

1C1 

1C5 

102 

81 

123 

102

30 days later

Nanograms

344 

941 

242 

223 

0 

155

310 

1,316 

249

247 

0 

151

280 

1,096 

241 

227 

0 

147

Percent

116 

81 

106

77 

0 

89

105 

114 

109 

85 

0 

87

95 

95 

1057y

0 

84

1 Summation of o, p'-DDT and p, p'-DDT.

The analytical procedure described was applied to th°. determination of chlorinated organic pesticides in unfiltered samples of water 

collected from streams in several States, and the results are given in 

table 4. To provide confidence in the results, all identifications were 

made on two different types of gas chromatographic columns: Dow-11 

and QF-1. A pesticide identified on one column but not confirmed on 

the other column was not reported in the results.

In this research, 4-liter samples were used, but smaller samples can 

be used in routine analysis. Most sources of contamination in the laboratory can be eliminated by precautions described in tl e section on 

"Interferences." Electron-capturing compounds (other than the pesticides) are present in some industrial wastes, and if these wastes are 

present in the water samples to the extent that they interfere with the 

analysis, either clean-up procedures or other methods of analysis will 

be necessary. Thus far, however, natural organic matter and agricultural pollution have not produced an interference problem in this 

research.

This method is a convenient and extremely sensitive procedure for 

the identification and measurement of organic pesticides having high 

electron affinities. Because chlorinated organic pesticides have high 

electron affinities, they can be separated and measured in the presence 

of compounds having low electron affinities. For example, the electron-capturing potential of many of the chlorinated organic pesticides 

is a million or more times greater than hexane.
CHLORINATED ORGANIC PESTICIDES Bll

TABLE 4.- -Electron-capture gas chromatographio analysis of chlorinated pesticides in unfiltered samples of surface water

Source

No. 1.

Location

Near Niland, Calif-.... -....

Date 

collected 

(1964)

Feb. 5

Feb. 5

May 13

Sept. 18

Sept. 19

Sept. 28

Pesticide found

Dieldrin- ______.

 -do...... 

. _ _do _ . . .

Heptachlor epoxide _

Dieldrin... ..

Heptachlor eporide.-.

Aldrin..-. __ ....

Endrin ______ ...

Dieldrin. 

Lindfine,..

Aldrin.. ..............

Endrin ......

Heptachlor epoxide...

Corcentratior (parts 

per trillion)

70

50

<10

<10 

10

10

<10 

<10

10

20

1,140

<10

<10

20

40

10

Measurable losses due to adsorption of the pesticide on the walls of 

the sample container are obviated because the walls of the container 

are exposed to the solvent. The recovery of the individual pesticides 

was good, average recoveries ranging from 89 to 104 percent. 67 this 

method, the pesticides may be determined on a sample of convenient 

size in concentrations as low as the parts-per-trillion range. Thir procedure has practical applications in surveillance programs, especially 

if prompt information or action is needed.

REFERENCES

Bowman, M. C., Acree, F., Jr., Lofgren, C. S. and Beroza, M., 1964, Chlor'nated

insecticides: Fate in aqueous suspensions containing mosquito larvae:

Science, v. 146, no. 3650, p. 1480-1481. 

Breidenbach, A. W. and Lichtenberg, J. J., 1963, DDT and dieldrin in rivers: A

report of the National Water Quality Network: Science, v. 141, no. 5384,

p. 899-901. 

Dugan, P. R., Pfister, R. M. and Sprague, M. L., 1963, Evaluation of the extent

and nature of pesticide and detergent involvement in surface waters of a

selected watershed: New York Health Dept. Research Rept. 10, pt. 1, 74 p. 

Goodenkauf, A. and Erdei, J., 1964, Identification of chlorinated hydrocarbon

pesticides in river water: Am. Water Works Assoc. Jour., v. 56, no. 5.

p. 600-606. 

Grzenda, A. R., Lauer, G. J. and Nicholson, H. P., 1964, The zooplankton, I ottoin

fauna, and fish [pt.] 2 of Water pollution by insecticides in an agricultural

river basin: Limnology and Oceanography, v. 9, no. 3, p. 318-323. 

Gutenmann, W. H. and Lisk, D. J., 1964, Gas chromatographic method for silvex:

Am. Water Works Assoc. Jour., v. 56, no. 2, p. 189-190. 

Hindin, E., Hatten, M. J., May, D. S., Jr., Skrinde, R. T. and Dunstan, G. H., 1962,

Analysis of synthetic organic pesticides in water: Am. Water Works Assoc.

Jour., v. 54, no. 1, p. 88-90. 

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B12 ORGANIC SUBSTANCES IN WATER

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O