METRIBUZIN AND METABOLITES IN WISCONSIN (USA) WELL WATER

Metribuzin is a commonly used pesticide in Wisconsin and elsewhere, al though contamination of groundwater by metribuzin has received little attention. A technique using solid phase extraction and high performan ce liquid chromatography was optimized to allow measurement of metribu zin and its major metabolites-deaminated metribuzin (DA), diketometrib uzin (DK) and deaminated diketometribuzin (DADK). Percent recoveries a nd precision of metribuzin and DA analyses were good. Recoveries and r eproducibility of DADK were acceptable (about 65%). However, the recov eries for DK were low (about 35%; the precision of the analysis was go od, however). Overall, accuracy and precision were as good as, or bett er than, reported in the literature. Metribuzin and metribuzin metabol ites were found in most of the groundwater samples analyzed from a num ber of wells located in sandy soil areas of Wisconsin. The parent metr ibuzin compound was found at concentrations ranging from not detected to 10.2 mug/l, while metabolite concentrations ranged from not detecte d to nearly 2 mug/l. Metabolites, which have been rarely reported to o ccur in water, were found in most of the samples even when the parent compound was absent.