A high performance liquid chromatographic method was developed to meet the U.S. Environmental Protection Agency's (EPA) Unregulated Contaminant Monitoring Rule (UCMR) Survey need for the analysis of phenylurea pesticides in drinking waters. Many of these phenylurea compounds were demonstrated to degrade rapidly in the presence of the residual chlorine disinfectant in drinking waters. This degradation was halted by the addition of a tris buffer, which was initially chosen to optimize the sample pH prior to extraction. Copper sulfate was found to prevent the regrowth of microorganisms in surface waters, which was observed upon dechlorination. Tris buffer provided the additional benefit of keeping the copper sulfate preservative in solution even in groundwater matrices that caused precipitation of copper in its absence. A C-18 solid phase, in cartridge or disk form, was used to efficiently extract target compounds from the preserved drinking water matrices. A 21-day storage stability study, together with precision and accuracy studies, demonstrated that this method had suitable sensitivity, selectivity, accuracy, precision, and ruggedness for use in the EPA's UCMR drinking water occurrence survey.
