An h.p.l.c. method for the quantitative determination of asulam, acetylasulam and sulphanilamide in peaches

An analytical method has been developed for the determination of the herbicide, asulam [methyl(4-aminobenzenesulphonyl)carbamate] and two metabolites, sulphanilamide and acetylasulam individually, in peaches. Asulam and acetylasulam were partitioned from an aqueous phase with ethyl ether, leaving behind more polar components which interfered with the analysis of these compounds. The sulphanilamide was next partitioned from the aqueous phase into ethyl acetate. Each fraction was then chromatographed on its own neutral alumina column, activity grade 1, and analysed by high performance liquid chromatography (h.p.l.c.) using a C-18 reverse phase column. From peach samples fortified at the 0.10 p.p.m. level, recoveries averaged 72% (asulam), 100% (acetylasulam) and 90% (sulphanilamide). No residues of these compounds were found in two studies of peaches harvested 0, 5, 10, 15 and 20 days following asulam treatment at 0-7.50 kg/ha.