title: Photochemical degradation of methylparathion in the presence of humic acid.
abstract: Photochemical degradation of methylparathion (O,O,-dimethyl O-4 nitrophenylphosphorothioate) in the presence of humic acid between pH 2 and 7 was monitored by differential pulse polarography. Humic acid was not electro-active under the experimental conditions used in this study. Only the pesticide and its main degradation product at pH 2 exhibited polarographic signals. Photolysis of methylparathion in acid media was sensitized by humic acid since the pesticide did not degrade in the absence of this compound. Methylparathion degradation in the presence of humic acid was observed at each of the studied pHs. The reaction was first-order with rate constant values ranging from 2 x 10(-3) to 6.3 x 10(-3) min(-1).
authors.affiliation: Department of Analytical Chemistry, Autonomous University of Yucatan, Yucatan, Mexico. mcano@uady.mx
authors.forename: Jose A
authors.initials: JA
authors.lastname: Manzanilla-Cano
authors.forename: Manuel H
authors.initials: MH
authors.lastname: Barcelo-Quintal
authors.forename: Tania I
authors.initials: TI
authors.lastname: Coral-Martinez
mesh_terms: D001673:Biodegradation, Environmental; D004563:Electrochemistry; D006812:Humic Substances; D007306:Insecticides / Q000737:chemistry*; D008743:Methyl Parathion / Q000737:chemistry*; D010777:Photochemistry
chemical_list: D006812:Humic Substances; D007306:Insecticides; D008743:Methyl Parathion