DETERMINATION OF METSULFURON METHYL AND ITS 2 METABOLITES IN CROPS BYLIQUID-CHROMATOGRAPHY WITH ULTRAVIOLET DETECTION

Metsulfuron methyl, its hydroxy metabolite (A1), and its glucose conju gate metabolite (A) were determined in several crops by liquid chromat ography (LC) using a simple extraction and cleanup scheme. After the p arent and 2 major metabolites were extracted from crops with methanol, metabolite A was enzymatically hydrolyzed to metabolite A1 with beta- glucosidase. The treated extracts were cleaned up chromatographically, and then metsulfuron methyl and metabolite A1 were quantitatively det ermined by reversed-phase LC with UV detection at 254 nm. Recovery of metsulfuron methyl and its 2 metabolites was 90 +/- 6% over a range of 0.005 to 0.4 ppm from fortified samples of brown grain, wheat, barley , sugarcane stalk, and oat straw. Method detection limits (MDLs) were 0.005 ppm for metsulfuron methyl, 0.006 ppm for metabolite A, and 0.00 3 ppm for metabolite Al in such crops as brown grain, wheat, barley, a nd sugarcane, and 0.01 ppm far metsulfuron methyl, 0.015 ppm for metab olite A, and 0.01 ppm for metabolite A1 in oat straw. The MDLs were es timated on the basis of a signal-to-noise ratio of 5 within a confiden ce interval of 95%. The method has potential application for the analy ses of these analytes in other crops and feeds and may be applicable t o other sulfonylurea herbicides.