PHOTOLYSIS OF METRIBUZIN IN OXYGENATED AQUEOUS-SOLUTIONS

The photochemical behaviour of metribuzin methylethyl)-3-methylthio-1. 2.4-triazin-5(4H)-one] and its known metabolites desaminometribuzin (D A), diketometribuzin (DK) and desaminodiketometribuzin (DADK) was inve stigated in aqueous oxygenated solutions at various pH values. The pho tochemical degradation of metribuzin over time and the formation and f urther fate of DA, DK and DADK were elucidated. Both sidechain degrada tion and ring opening were detected as a result of photolysis. Six unk nown metabolites as a result of side-chain degradation, including 6-az auracile, 6-azathymine and 4-aminosubstituted derivatives, were identi fied as very stable photodegradation products. Furthermore, some inorg anic and organic ionic compounds were detected such as monocarboxylic, dicarboxylic and ketocarboxylic acids formed by side-chain degradatio n and ring cleavage. (C) 1998 Elsevier Science Ltd.