Gas-Liquid Chromatographic Determination of Organophosphorus Insecticide Residues in Fruits and Vegetables

Abstract

A method intended for regulatory purposes is described for the determination of organophosphorus insecticide residues in fruits and vegetables. Eighteen organophosphorus insecticides, azinphos-ethyl, chlorpyrifos, diazinon, dichlorvos, dimethoate, ethion, ethoate-methyl, fenitrothion, fenthion, formothion, malathion, methidathion, mevinphos, parathion, phosalone, phosphamidon, thiometon, and trichlorphon, and 7 metabolites, fenitrooxon, fenthion sulfoxide, fenthion sulfone, malaoxon, desethylphosphamidon, thiometon sulfoxide, and thiometon sulfone, were extracted from different crops with acetone and partitioned into hexane or ethyl acetate, according to their polarities. The hexane extract was cleaned up by eluting from a Florisil column with acetone-hexane (4+96). The ethyl acetate extract needs no cleanup. The concentrated extracts were analyzed by gasliquid chromatography using thermionic detectors. Recoveries conducted at fortification levels ranging from 0.1 to 2 mg/kg were in most cases above 80%. The limit of sensitivity is less than 0.1 mg/kg.

Residues of dimethoate and omethoate in peaches and apples following repeated applications of dimethoate

“…Both peach and apple samples were analyzed for the determination of dimethoate and omethoate. Extraction was carried out by blending at high speed for 3 min with acetone, according to the general method of Ferreira and Silva Fernandes (1980) used in this laboratory for the determination of organophosphorus insecticides in fruits and vegetables, but the amount of samples and extracting solvent has been doubled. An aliquot of the aqueous acetone, equivalent to a 50-g sample, was transferred into a separatory funnel, 75 mL of water added, and partition carried out with two 50-mL portions of hexane.…”

Comparison of Soxhlet and Microwave-Assisted Extractions for the Determination of Fenitrothion Residues in Beans

“…Möllhoff () determined fenitrothion residues in apple, lettuce, carrot, onion, tomato, and potato by electron capture gas chromatography (EC-GC) after Florisil column cleanup. GC determination of fenitrothion residues in vegetables and fruits using a selective NPD detector has been also reported ( , ). Funch () reported a high-performance liquid chromatography (HPLC) method for analyzing fenitrothion residues in apple.…”