A rapid multi-residue method for the determination of pesticide residues in choi sum, yardlong beans and aubergines

A rapid multi-residue modified QuEChERS method has been developed to analyse 20 pesticide residues in choi sum, yardlong beans and aubergines by gas chromatography with flame photometric and electron capture detectors. Primary secondary amine in dispersive form was omitted in the extraction step but instead packed in a Pasteur glass pipette for column cleanup. The recoveries for all 20 pesticides except chlorothalonil at 10–500 μg kg−1 fortification levels ranged from 74.0% to 117%. Similar recoveries of 81.7–117% were obtained for all organochlorine and pyrethroid pesticides including chlorothalonil using silica gel cleanup. The relative standard deviation obtained was below 14.9%. The limit of quantification was in the range 1–10 μg kg−1. The method has high selectivity for pesticides in vegetables containing high amount of chlorophyll, pigment and coloured compounds such as in choi sum and aubergines. The method was used to analyse 132 vegetable samples from residue survey.