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-sev en pesticides (twelve organohalogens, forty-five organonitrogens, elev en organophosphorus and nine pyrethroids) in agricultural products is proposed. Pesticide residues were extracted from crop samples with ace tone followed by dichloromethane partitioning. Crop extracts were clea ned-up by gel permeation chromatography equipped with a 10 mm diameter column. Analytical screening was by gas chromatography using long, na rrow-bore fused-silica open-tubular columns equipped with electron-cap ture 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 chlormep hos (51.5%). Limits of detection were less than 0.01 mg/kg for ECD. Co nfirmation of pesticide identity was performed by gas chromatography-m ass spectrometry in selected-ion monitoring mode. The multiresidue pro cedure was applied in routine crop analysis: a 9-month period data are reported. (C) 1997 Elsevier Science B.V.