Organophosphorus Insecticide Residues Research Articles

Rapid procedures for the routine determination of organophosphorus insecticide residues in vegetables : II. A screening procedure for water-soluble insecticides

A screening procedure is described for the determination of residues of the more polar organophosphorus insecticides in vegetables. The method is based on aqueous extraction, partition into chloroform, alumina column clean-up and coloritmetric determination of total pesticide phosphorus. Screening limits for sixteen organophosphorus insecticides and metabolites were in the range 0.05–0.1 p.p.m., depending on the particular insecticide.

Rapid procedures for the routine determination of organophosphorus insecticide residues in vegetables I. Determination of hexane-soluble insecticides by gas—liquid chromatography and total-phosphorus procedures

Two procedures are described for the determination of the less polar organo-phosphorus insecticides in vegetables, based on acetone—hexane extraction and alumina column clean-up techniques previously reported. Details are given of a screening method based on the colorimetric determination of pesticidal phosphorus in cleaned-up extracts and capable of screening for eleven insecticides at the 0.06−0.1 p.p.m. level, depending on the insecticide. A second procedure using the phosphorus-specific thermionic detector to identify and quantitatively measure residues of these same eleven compounds is also described. When the latter technique is combined with the previously reported method for organochlorine insecticide residues1, the combined method has been shown to be suitable for the determination of thirty-one insecticide residues. Thirty of these insecticides can be readily determined at the 0.01 p.p.m. level and most insecticides in most vegetables at the 0.002 p.p.m. level. Azinphos methyl can be determined at the 0.02 p.p.m. level.

Cleanup procedure for water, soil, animal and plant extracts for the use of electron-capture detector in the gas chromatographic analysis of organophosphorus insecticide residues

A simple, aqueous acetonitrile partition cleanup method for analyses of some common organophosphorus insecticide residues is described. The procedure described is for cleanup and quantitative recovery of parathion, methyl parathion, diazinon, malathion and thimet from different extracts. Those insecticides in the purified extracts of ground water, grain, soil, plant and animal tissues can be detected quantitatively by gas chromatography with an electron capture-detector at 0.01 ppm. Cleanup is satisfactory for paper and thin-layer chromatography for further identification of individual insecticides in the extracts.

An assessment of some methods of analysis for dimethoate residues in fruit and vegetables

Three methods for determining residues of dimethoate, OO-dimethyl S-(N-methylcarbamoylmethyl) phosphorodithioate, in fruits and vegetables have been investigated for the purpose of recommending a standard method that can be applied to a variety of temperature fruits grown in the United Kingdom. Laws and Webley's general method for determining organophosphorus insecticide residues was satisfactory for residues of dimethoate in sprouts, lettuces and apples, but not in peas. Chilwell and Beecham's procedure was also satisfactory at the 1 or 2 p.p.m. level of added dimethoate in cabbages, lettuces, apples and peas. Giang and Schechter's method, however, gave variable results.