Multiresidue analysis of pesticides in fruits and vegetables by gel permeation chromatography followed by gas chromatography with electron-capture and mass spectrometric detection

A wide range screening method for multiresidue analysis of seventy-seven pesticides (twelve organohalogens, forty-five organonitrogens, eleven organophosphorus and nine pyrethroids) in agricultural products is proposed. Pesticide residues were extracted from crop samples with acetone followed by dichloromethane partitioning. Crop extracts were cleaned-up by gel permeation chromatography equipped with a 10 mm diameter column. Analytical screening was by gas chromatography using long, narrow-bore fused-silica open-tubular columns equipped with electron-capture detection (ECD). Recoveries of majority of pesticides from spiked samples of carrot, melon and tomato at fortification levels of 0.04-0.10 mg/kg ranged from 70 to 108%, The lowest recovery was for chlormephos (51.5%). Limits of detection were less than 0.01 mg/kg for ECD, Confirmation of pesticide identity was performed by gas chromatography-mass spectrometry in selected-ion monitoring mode. The multiresidue procedure was applied in routine crop analysis: a 9-month period data are reported.