Multiresidue analysis of organophosphorus pesticides in vegetables and fruits using dual-column GC-FPD, -NPD

Abstract

We investigated simultaneous and consecutive analytical methods for pesticide residues in large numbers of vegetable and fruit samples. Extraction of the sample with acetonitrile was followed by a salting-out step using a graduated cylinder. Co-extractives were removed by gel permeation chromatography (GPC) and the pesticide eluate was separated to 2 fractions. Firstly, the second fraction (85∼125 mL) was passed through a silica-gel mini-column. After putting a Florisil mini-column before the silica-gel mini-column, the first fraction (55∼85 mL) was passed through the tandem mini-columns, which were then eluted with 15 mL of 50% acetone/petroleum ether. The eluate was subjected to dual-column GC with dual FPD (P mode, column Rtx®-OPPesticides) and NPD (column Rtx®-200) detectors. Recoveries of 63 organophosphorus pesticides from fortified spinach, tomato, apple and strawberry, ranged from 71 to 126% with RSD values of 1∼18%, except for the RSDs of omethoate, isoxathion, and pyraclofos (20%