SOLID-PHASE EXTRACTION, CLEANUP AND LIQUID-CHROMATOGRAPHY FOR ROUTINEMULTIRESIDUE ANALYSIS OF NEUTRAL AND ACIDIC PESTICIDES IN NATURAL-WATERS IN ONE RUN

Solid-phase extraction using C-18 silica cartridges, liquid chromatogr aphy analysis and UV diode array detection were investigated for the r outine trace-level determination of neutral pesticides over a wide ran ge of polarity. Detection limits below the 0.1 mu g/l range were easil y obtained in drinking water. Lf neutral and acidic pesticides over a wide range of polarity have to be determined in the same run, samples have to be acidified to obtain good recoveries of extraction. The effe ct of the sample matrix was studied and detection limits in the 0.1 mu g/l range were obtained in drinking water except for the more polar o nes which are in the interfering peak of humic and fulvic acids. For s urface water, a clean-up step using a Florisil cartridge has to be inc luded in the procedure that allows detection limits in the range 0.05- 0.3 mu g/l.