METRIBUZIN AND METABOLITES IN WISCONSIN (USA) WELL WATER

Metribuzin is a commonly used pesticide in Wisconsin and elsewhere, although contamination of groundwater by metribuzin has received little attention. A technique using solid phase extraction and high performance liquid chromatography was optimized to allow measurement of metribuzin and its major metabolites-deaminated metribuzin (DA), diketometribuzin (DK) and deaminated diketometribuzin (DADK). Percent recoveries and precision of metribuzin and DA analyses were good. Recoveries and reproducibility of DADK were acceptable (about 65%). However, the recoveries for DK were low (about 35%; the precision of the analysis was good, however). Overall, accuracy and precision were as good as, or better than, reported in the literature. Metribuzin and metribuzin metabolites were found in most of the groundwater samples analyzed from a number of wells located in sandy soil areas of Wisconsin. The parent metribuzin compound was found at concentrations ranging from not detected to 10.2 mug/l, while metabolite concentrations ranged from not detected to nearly 2 mug/l. Metabolites, which have been rarely reported to occur in water, were found in most of the samples even when the parent compound was absent.