title: Application of liquid chromatography/electrospray ionization tandem mass spectrometry for the elucidation of hydroxyl radical oxidation of metsulfuron methyl and related sulfonylurea pesticide products: evidence for the triazine skeleton scission.
abstract: BACKGROUND
  Sulfonylureas are among the most important class of antidiabetic and herbicides. Solar light excitation and Advanced Oxidation Processes may result in the formation of a wide array of products owing to the relative complex structure. These products, that should be identified, may present a more toxic effect than the parent compound.
  
  
  METHODS
  Liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI-QTOFMS) with accurate mass determination emerges as a valuable technique for the precise elucidation of all possible byproducts. The hydroxyl radical was generated by excitation of the iron(III) aquacomplex [Fe(H(2)O)OH](2+) and hydrogen peroxide at pH 3.5. Three different sulfonylureas were studied: metsulfuron methyl, cinosulfuron and thifensulfuron methyl.
  
  
  RESULTS
  Several products owing to the reactivity of hydroxyl radicals with sulfonylurea were obtained. They arise from scission of the sulfonylurea bridge, hydroxylation of the aromatic ring, demethylation of the methoxy group and more importantly and unequivocally from the rupture of the triazine skeleton. To reach such scission, a primary demethylation of the methoxy group on the triazine moiety seems to act as a precursor process. Such a process was observed with the three studied sulfonylurea compounds.
  
  
  CONCLUSIONS
  The reported results demonstrated the usefulness of accurate mass measurements undertaken by LC/ESI-QTOFMS for structural elucidation of the unknown byproducts that were generated during hydroxyl radical reactions with some sulfonylureas. It has been possible herein to identify the structures of products arising from the opening of the recalcitrant triazine structure via hydrolysis processes in acidic solutions.
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF), Equipe Photochimie, BP 10448, F-63000, Clermont-Ferrand, France.|CNRS, ICCF UMR 6296, Photochemistry Team, BP 80026, F-63171, Aubière, France.|Laboratoire des Sciences de l'Environnement et du Développement, Equipe de Chimie Ecologique, FST Université Hassan 1er, Km 3 route de Casablanca, BP 577, Settat, Morocco.
authors.forename: Rajae
authors.initials: R
authors.lastname: Chahboune
authors.affiliation: Laboratoire des Sciences de l'Environnement et du Développement, Equipe de Chimie Ecologique, FST Université Hassan 1er, Km 3 route de Casablanca, BP 577, Settat, Morocco.
authors.forename: Hafida
authors.initials: H
authors.lastname: Mountacer
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF), Equipe Photochimie, BP 10448, F-63000, Clermont-Ferrand, France.|CNRS, ICCF UMR 6296, Photochemistry Team, BP 80026, F-63171, Aubière, France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Sarakha
mesh_terms: D001190:Arylsulfonates / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D010084:Oxidation-Reduction; D010575:Pesticides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013453:Sulfonylurea Compounds / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods; D014227:Triazines / Q000737:chemistry
chemical_list: D001190:Arylsulfonates; D010575:Pesticides; D013453:Sulfonylurea Compounds; D014227:Triazines; C050296:metsulfuron methyl