Portions of several previously reported methods have been combined, condensed, and modified to provide a rapid, simple procedure for determining chlorinated organic pesticide residues in nonfatty foods. The method is believed to be applicable to 21 pesticides in a variety of foods. Results are reported for 5 pesticides in 11 foods.

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Two crops, lettuce and kale, were treated with a maneb formulation at a rate of 2.4 lb active/acre. Samples were harvested at various times after application for residue analysis. The residues determined were maneb and ethylene thiourea (ETU). On lettuce, residues of maneb decreased from 45 to 5 ppm in 15 days. On kale, the decrease was from 90 to 15 ppm in 7 days. With both crops, ETU which was already present in the formulation did not accumulate, but quickly decreased from 0.6 ppm to undetectable amounts after 7 days.

Thin layer and gas chromatographic methods have been developed for the determination of ethylene thiourea in fruits, vegetables, and milk. The food sample is extracted with an ethanol-chloroform mixture and partially cleaned up on a cellulose column. For TLC determination, an aliquot (5–25 g) is further cleaned up on an aluminum oxide column. The remainder of the sample is treated with a methanolic solution of 1-bromobutane and the resultant derivative is isolated and measured by GLC, using a thermionic detector. Recoveries at fortification levels of 0.02 to 10 ppm exceeded 80%.