Determination of organophosphorus and carbamate insecticides in fresh fruits and vegetables by high-performance thin-layer chromatography-multienzyme inhibition assay.

HPTLC-enzyme inhibition assay was applied to different fruit and vegetable samples after individual spiking with organophosphate and carbamate pesticides at their maximum residue limits documented by the European Commission. Samples were extracted according to the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method, including cleanup by primary secondary amine sorbent. Additional cleanup was performed on the HPTLC plate by a prechromatographic step to separate most coextracted matrix compounds from 20 different pesticides under study. With both rabbit liver esterase and cutinase from Fusarium solani pisi as enzyme sources, mean recoveries from apples, cucumbers, grapes, nectarines, plums, tomatoes, and lemons were in the ranges 86-109, 95-129, 96-114, and 90-111% for chlorpyrifos, paraoxon, parathion, and pirimicarb, respectively, with a mean RSD of 8.5% for all samples.