Liquid chromatography/electrospray ionisation sequential mass spectrometric identification of the main chlortoluron by-products during water disinfection using chlorine

The main degradation by-products of the herbicide chlortoluron formed durin g water disinfection with HOCl/ClO- have been separated and identified by l iquid chromatography/electrospray ionisation sequential mass spectrometry ( LC/ESI-MSn). Chlorination and hydroxylation reactions seem to occur exclusi vely on the aromatic ring of chlortoluron, leading to by-products which sho w characteristic fragmentation patterns. Indeed, chlortoluron-like ESI spec tra were always observed for chlorinated byproducts, showing only a fragmen t at m/z 72, In contrast, hydroxylated and chloro/hydroxylated byproducts g ave a much more complex fragmentation pattern that could be elucidated by M Sn (n = 1-4) experiments, A mechanistic scheme rationalising the observed f ragmentation pattern is proposed and discussed. Copyright (C) 2000 John Wil ey & Sons, Ltd.