DETERMINATION OF PESTICIDE-RESIDUES IN WATERS FROM SMALL LOUGHS BY SOLID-PHASE EXTRACTION AND COMBINED USE OF GAS-CHROMATOGRAPHY WITH ELECTRON-CAPTURE AND NITROGEN-PHOSPHORUS DETECTION AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH DIODE-ARRAY DETECTION

A procedure for the determination of pesticide residues in waters from small loughs surrounded by different crops has been developed. For th is purpose, a solid-phase extraction procedure with octadecylsilane ca rtridges was used, optimizing the elution parameters as well as the br eakthrough volume and the influence of the pesticide amount. The recov eries of the pesticides can be improved by about 10-20%. Extracts were analyzed either by gas chromatography with electron-capture and nitro gen-phosphorus detection or high-performance liquid chromatography wit h diode array detection to achieve a more reliable identification and determination of twenty-three pesticides from different chemical famil ies, including triazines, phenylureas and organophosphorus. (C) 1997 E lsevier Science B.V.