Application of coupled liquid chromatography–mass spectrometry in hydrolysis studies of the herbicide ethametsulfuron-methyl

The hydrolysis of the sulfonylurea herbicide ethametsulfuron-methyl [methyl 2-[[[[(4-ethoxy-6-methylamino-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]benzoate] was studied in aqueous buffers of different pH values. The reaction was first-order and pH-dependent. Ethametsulfuron-methyl was more persistent in neutral or weakly basic than in acidic solution. Eleven degradation products were detected and tentatively identified by LC/MS/MS analysis. At all pH values studied, the primary pathway of degradation was the cleavage of the sulfonylurea bridge. However, minor degradation pathways have also been observed, such as O-de-ethylation, N-demethylation, and opening of the triazine ring.