title: Photo-induced degradation of diuron in aqueous solution by nitrites and nitrates: kinetics and pathways.
abstract: The photo-induced degradation of diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) in aqueous solution under simulated solar irradiation has been investigated in the presence of NO3-/NO2- ions. The degradation rates were compared by varying environmental parameters including substrate and inducer concentrations, oxygen content and pH. The photoproducts were identified by extensive LC-ESI-MS and LC-ESI-MS-MS studies after SPE preconcentration on prepacked cartridges. In both NO3- and NO2- conditions, oxidation of the N-(CH3)2 terminus group is the main process leading to the N-monodemethylated (NHCH3), N-formyl (N(CH3)CHO) and the uncommon and unstable carbinolamine (N(CH3)CH2OH) by-products. Cl/OH substituted and nitrated phenylureas are formed minorily. Degradation pathways involving OH* and NO2* (or dimer) radicals as reactive species are proposed.
authors.affiliation: Unité de Phytopharmacie et Médiateurs Chimiques, INRA, Route de St-Cyr, 78026 Versailles Cedex, France.
authors.forename: M V
authors.initials: MV
authors.lastname: Shankar
authors.forename: S
authors.initials: S
authors.lastname: Nélieu
authors.forename: L
authors.initials: L
authors.lastname: Kerhoas
authors.forename: J
authors.initials: J
authors.lastname: Einhorn
mesh_terms: D001673:Biodegradation, Environmental / Q000187:drug effects / Q000528:radiation effects; D002853:Chromatography, Liquid; D004237:Diuron / Q000032:analysis / Q000493:pharmacokinetics*; D006540:Herbicides / Q000032:analysis / Q000493:pharmacokinetics*; D006863:Hydrogen-Ion Concentration; D016014:Linear Models; D009566:Nitrates / Q000494:pharmacology*; D009573:Nitrites / Q000494:pharmacology*; D010777:Photochemistry / Q000379:methods*
chemical_list: D006540:Herbicides; D009566:Nitrates; D009573:Nitrites; D004237:Diuron