Determination of organophosphorus pesticide metabolites in surface water by use of a strong anion-exchange disk and in-vial derivatization

Determination of the metabolites of organophosphorus pesticides by means of a strong anion-exchange disk (SAX) and direct derivatization has been evaluated in this study. Five metabolites in water were extracted and concentrated by means of an SAX disk and then derivatized directly with methyl iodide in acetonitrile. Capillary column gas chromatography with flame photometric detection (GC-FPD) tvas used for quantification. Recoveries were approximately 76-96 % and wen relatively stable throughout a broad pH range (6.5-12.0). The detection limits for these metabolites were approximately 0.021-0.12 mu g L-1 for a 100-mL sample. Results from analysis of water samples collected from a fruit-growing area were indicative of the applicability of the method. Compared with methods reported in the literature, the method established in this study not only enables substantial simplification of sample preparation but also reduces the consumption of solvents during sample pretreatment. The method can be used to determine trace amounts of organophosphorus pesticides in surface waters to accommodate the increasing need for environmental monitoring.