Collaborative study of a method for Sevin insecticide residues was repeated with apples and lettuce as test crops. The method is based on alkaline hydrolysis of Sevin and colorimetric determination of the resulting 1-naphthol with p-nitrobenzenediazonium fluoborate as chromogenic agent. Data from 5 collaborators were in good agreement with an average recovery of 87.8% at 2 concentration levels. It is recommended that the method be adopted as official, first action.

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Improved spectrophotometric methods have been developed for separate determinations of BHA and BHT in vegetable oils. The methods are applicable in the presence of other synthetic antioxidants and are adaptable to BHA and BHT concentrations ranging from 5 to 200 ppm. BHA is nitrosated directly in the oil and the nitroso product is isolated by a combination of solvent extraction and liquid chromatographic techniques. An alkaline solution of the product is measured spectrophotometrically at 480 mμ, and the absorbance is referred to a calibration curve to determine the BHA concentration. Both the 2- and 3-isomers yield approximately the same absorptivity, and Beer's Law is obeyed from 0 to 50 μg BHA/ml final solution. BHT is determined by its ultraviolet absorption at 283 mμ. The compound is separated from the oil by direct extraction into acetonitrile. BHT is isolated from BHA and other extraneous materials by chromatography on alumina

Temik, 2-methyl-2-(methylthio) propionaldehyde O-(methylcarbamoyl)oxime, is a systemic pesticide effective both by topical application to the plant and by systemic translocation from treated soil. The method developed for residues of Temik in crops is based on extraction of the crops with chloroform, followed by cleanup involving both coagulation and liquid partitioning techniques. The analysis involves both base- and acid-catalyzed hydrolysis to liberate hydroxylamine, which is then oxidized by iodine to nitrous acid; the latter is determined by diazotization (a modification of the Griess test for nitrites). The method is sensitive to about 0.03 ppm; average recovery from 8 crops is 96.3 ± 3.2%. Other current commercial pesticides do not interfere in the analysis.

Colorimetric methods are described for determining Sevin and its metabolities, 1 -naphthol and 1 -naphthol conjugates, in poultry tissues and eggs. Free naphthol is reacted with pnitrobenzenediazonium fluoborate to produce a colored product which is measured spectrophotometrically. Sevin and 1 -naphthol conjugates are hydrolyzed to 1 -naphthol which is then determined in the same manner.Residue studies with poultry dusted with Sevin showed highest concentrations of residues to be in skin tissue where an average of 1 9.3 p.p.m. Sevin was found 1 day after the final treatment. A 7-day waiting period between treatment and slaughter reduced these residues to 2.15 p.p.m. No significant amount of either 1 -naphthol or its conjugates was found in any tissue of birds processed 7 days after treatment, and eggs were found free of residues throughout the study. Sevin(1-naphthyl '-methylcarbamate), a broad spectrum insecticide developed by Union Carbide Chemicals Co., has proved highly effective for controlling chicken mites, northern fowl mites, lice, and other ectoparasites of poultry (7). Control is gained by treating the litter in the cages or by direct application of the insecticide to the birds.To study the extent of contamination that may result in the edible tissues of birds treated with Sevin, a dusting experiment was conducted jointly between the Research and Development Department of Union Carbide Chemicals Co. and the Zoology-Entomology Department of Auburn University. The experiment was designed to provide residue data in all types of edible tissue for both the parent insecticide and its metabolite, 1-naphthol. Each type of tissue, including skin, dark and white muscle, liver, and gizzard, was analyzed separately to show' the distribution of residues in the carcass.