title: Photodegradation of the herbicide penoxsulam in aqueous methanol and acetonitrile.
abstract: Penoxsulam is a triazolopyrimidine sulfonamide group of rice herbicide. The phototransformation of penoxsulam was studied under UV light (lambda max >or= 290 nm) and sunlight in aqueous methanol and acetonitrile solvent system using TiO2 as sensitizer. The rate of photodegradation of penoxsulam in different solvent systems followed first-order kinetics and calculated half-lives was found to be in the range of 51.89-73.41 h and 62.70-97.09 h for UV light and sunlight respectively in the presence or absence of sensitizer. From this study, a total of six photoproducts were identified and characterized on the basis of Q-Tof micromass spectral data. The plausible mechanism of phototransformation involved were hydrolysis, photo oxidation of the sulfonamide group, breaking of sulfonamide bond, loss of amino and sulfonic acid group.
authors.affiliation: Pesticide Residue Laboratory, Department of Agricultural Chemicals, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India. skpramanik@gmail.com
authors.forename: Sukhendu K
authors.initials: SK
authors.lastname: Pramanik
authors.forename: Saktipada
authors.initials: S
authors.lastname: Das
authors.forename: Anjan
authors.initials: A
authors.lastname: Bhattacharyya
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D000432:Methanol / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry; D013449:Sulfonamides / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays; D014529:Uridine / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D000097:Acetonitriles; D006540:Herbicides; D013449:Sulfonamides; D014867:Water; C009495:titanium dioxide; C504402:penoxsulam; D014025:Titanium; D014529:Uridine; D000432:Methanol; C032159:acetonitrile