DETERMINATION OF PESTICIDES IN DRINKING-WATER BY ONLINE SOLID-PHASE DISK EXTRACTION FOLLOWED BY VARIOUS LIQUID-CHROMATOGRAPHIC SYSTEMS

C-18 Empore extraction disks were coupled on-line with liquid chromatography-rapid scanning UV-VIS detection and post-column fluorescence detection for the isolation and trace enrichment of various pesticides [carbamates, (aldicarb, carbofuran, carbaryl), carbamate transformation products (TPs) (aldicarb sulfoxide, aldicarb sulfone, 3-hydroxycarbofuran, 3-hydroxy-7-phenol carbofuran, 3-keto-carbofuranphenol and 3-ketocarbofuran) and herbicides (chlortoluron, isoproturon and metolachlor)] spiked at concentration levels of 0.2 and 5 mug/l in drinking water samples. Recoveries were dependent on the pesticide level and preconcentrated water volume (50 ml to 1000 ml) using LC with rapid scanning UV-VIS detection. The same on-line system coupled with LC-post-column derivatization fluorescence detection has needed only 10 ml of water to achieve similar levels of determination for the carbamate insecticides.