Multiresidue analysis of pesticides in foods using acetonitrile extraction, gel permeation chromatography and mini-column cleanup, and dual-column GC-ECD

We investigated simultaneous and consecutive analytical methods for pesticide residues in large numbers of food samples using acetonitrile extraction, followed by gel permeation chromatography (GPC) and mini cartridge column cleanup, and then dual-column GC. A new apparatus with a graduated cylinder for vacuum filtration, salting-out and separation of a fixed quantity of the acetonitrile layer was developed. A test solution, cleaned up with GPC (column, Shodex(R) CLNpak EV-2000 and mobile phase, acetone-cyclohexane (1 : 4)) and with a silica-gel mini column, was subjected to dual-column GC (Rtx(R)-CLPesticides and Rtx(R)-CLPesticides2) equipped with ECD. Florisil mini-column fractionation was effective for further clean-up. Recoveries of 58 pesticides from fortified spinach, tomato, apple and strawberry were very good (70-121%), except for acrinathrin, captan, captafol, dichlofluanid, and etridiazol (< 70%). Detection limits of all of 58 pesticides were 0.1-5 ng/g. Surveillance of pesticides in vegetables and fruits was carried out by using the present method. From 21 out of 31 samples, 19 (50 in total) pesticides were detected within a period of about 3 days. The present method was compared with the bulletin method of residue analysis, and was demonstrated to have almost the same degree of sensitivity in detecting these pesticides. The results indicated that the present method can be applied as an efficient and reliable way of monitoring pesticide residues in foods.