| Abstract: | A capillary column gas chromatographic method is described for determining parts-per-trillion (ppt) levels of chlorsulfuron in agricultural runoff water. The water sample is acidified with acetic acid and extracted with methylene chloride. The chlorsulfuron in the extracts derivatized to its monomethyl derivative. After Florisil column cleanup, the methylated chlorsulfuron is determined by electron-capture gas chromatography. Recovery of chlorsulfuron from fortified water samples is greater than 80%. Detection limit of the method is 25 ng chlorsulfuron/L water (25 ppt). There are 2 reaction sites on the chlorsulfuron molecule, both of which are susceptible to methylation leading to monomethyl chlorsulfuron and dimethyl chlorsulfuron. A procedure is described to methylate selectively the sulfonamide nitrogen of chlorsulfuron. |
