title: Development of HPLC/ESI-MS and HPLC/1H NMR methods for the identification of photocatalytic degradation products of iodosulfuron.
abstract: In the present study, HPLC/ESI-MS and stopped-flow HPLC/1H NMR methods were developed and applied to separate and characterize the byproducts arising from TiO2-catalyzed photodegradation of the herbicide iodosulfuron methyl ester (IOME) in aqueous solution under UV irradiation. Prior to identification, irradiated solutions of IOME (200 and 1000 mg.L(-1)) were concentrated by solid-phase extraction using two cartridges: Isolute C18 and Isolute ENV+. Analytical separation was achieved on a C18 reversed-phase column with ACN/H2O (HPLC/MS) or ACN/D2O (HPLC/NMR) as mobile phase and a linear gradient with a chromatographic run time of 35 min. The combination of UV and MS data allowed the structural elucidation of more than 20 degradation products, whereas 1H NMR data permitted an unequivocal confirmation of the identities of major products and the differentiation of several positional isomers, in particular, the hydroxylation isomers. The obtained results permitted us to propose a possible degradation scheme and to put in evidence the presence of privileged sites for the attack of OH radicals. This work shows, for the first time, the application of combined HPLC with UV, MS, and NMR detection for complete structural elucidation of photocatalytic degradation products, and it will be of particular value in studies on the elimination of pollutants in aqueous solutions by photocatalysis.
authors.affiliation: Laboratoire d'Application de la Chimie à l'Environnement, UMR 5634, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France. mohamad.sleiman@univ-lyon1.fr
authors.forename: Mohamad
authors.initials: M
authors.lastname: Sleiman
authors.forename: Corinne
authors.initials: C
authors.lastname: Ferronato
authors.forename: Bernard
authors.initials: B
authors.lastname: Fenet
authors.forename: Robert
authors.initials: R
authors.lastname: Baudot
authors.forename: Farouk
authors.initials: F
authors.lastname: Jaber
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Chovelon
mesh_terms: D002384:Catalysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004952:Esters / Q000737:chemistry / Q000528:radiation effects; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D010777:Photochemistry; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry / Q000528:radiation effects; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013449:Sulfonamides / Q000737:chemistry* / Q000528:radiation effects*; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry
chemical_list: D004952:Esters; D012996:Solutions; D013449:Sulfonamides; D014867:Water; C009495:titanium dioxide; D014025:Titanium; C474738:iodosulfuron