Abstract
The photodegradation of an insecticide, dipropyl 4-(methylthio)phenyl phosphate (propaphos), was investigated under xenon lamp irradiation. Propaphos was easily decomposed after 60min irradiation, and the wavelengths for the 50% recovery in methanol solutions after constant irradiation for 60min were 318nm in the 12.5ppm solution, 314nm in the 100ppm solution and 312nm in the 200ppm solution, respectively, and those in water solutions 344nm in the 12.5ppm solution and 339nm in the 100ppm solution, respectively. Oxidation and hydrolysis were the main reactions involved in the photodegradation of propaphos. As the photodegradation products, dipropyl 4-(methylsulfinyl)phenyl phosphate, dipropyl 4-(methylsulfonyl)phenyl phosphate, dipropyl 4-(methoxysulfinyl)phenyl phosphate and dipropyl phenyl phosphate were tentatively identified by gas chromatography-mass spectrometry in the methanol solutions, and dipropyl 4-(methylsulfinyl)phenyl phosphate, dipropyl 4-(methylsulfonyl)-phenyl phosphate, 4-(methylthio)phenol, 4-(methylsulfinyl)phenol, 4-(methylsulfonyl)phenol, 1, 4-benzenediol, 4-hydoxythiophenol and dipropyl phenyl phosphate in the water solutions.
