Identification of photoproducts from imazosulfuron by HPLC

Photolysis of imazosulfuron was studied in aqueous solution under UV light. The reaction followed a pseudo‐rst‐order kinetic with signicant correlation coefcient. The major photodegradation products of imazosulfuron after irradiation under UV light were separated and tentatively identied by HPLC‐MS analysis as (4,6‐dimethoxypyrimidine‐2‐yl)aminocarbonylsulfamic acid, 4,6‐dimethoxy‐2‐ureidopyrimidine and 2,2′‐dichloro‐[3,3′] bi [imidazo[1,2‐a] pyridinyl]. The results indicate that different reaction pathways are followed: (1) cleavage of the sulfonylurea bridge; (2) desulfonylation, which can proceed either by a carbon–sulfur cleavage or a nitrogen–sulfur cleavage. A mechanism for the formation of the photoproducts is proposed. Copyright © 2004 John Wiley & Sons, Ltd.