Ozonation Products of Organophosphorous Pesticides in water

Abstract

Primary degradation products of organophosphorous pesticides by ozonation in water and the oxidation pathways of diazinon, fenthion (MPP) and edifenphos (EDDP) were studied by gas chromatography-mass spectrometry. Mass-spectra of ozonation products of the 17 organophosphorous pesticides evaluated suggested that they were oxons. Organophosphorous pesticides were converted to oxons in accordance with production of sulfate ion as their thiophosphorile bonds were oxidized by ozone into phosphorile bonds. Although oxons were stable against ozonation, they were further hydrolyzed into trialkyl phosphate and other hydrolysis products. However, in MPP, thiomethyl radicals were -oxidized prior to thiophosphorile bonds and MPP-sulfoxide was produced. MPP-sulfone, MPP-sulfoxide-oxon and MPP-sulfone-oxon were also generated from MPP. Two major oxidization products were obtained from bis-dithio type ethion. EDDP of the phosphate type was resistant to ozonation, but its oxidization products were detected after hydrolysis. © 1994, The Pharmaceutical Society of Japan. All rights reserved.