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

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 similar to 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 similar to 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(R)-OPPesticides) and NPD (column Rtx(R)-200) detectors. Recoveries of 63 organophosphorus pesticides from fortified spinach, tomato, apple and strawberry, ranged from 71 to 126% with RSD values of 1 similar to 18%, except for the RSDs of omethoate, isoxathion, and pyraclofos (20%<). Detection limits of pesticides were 0.5<similar to>2 ng/g. Surveillance of pesticides in vegetables and fruits was carried out by using the present method. From 20 out of 30 samples, 15 pesticides (39 in total) were detected. The results indicated that the present method can be applied as an efficient and reliable tool for monitoring organophosphorus pesticide residues in vegetables and fruits.