Application of solid-phase microextraction for monitoring the photocatalytic decomposition of fenthion and parathion in aqueous TiO2 suspensions

The photocatalytic degradation of the organophosphorus insecticides fenthion and ethyl parathion has been studied in aqueous titanium dioxide suspensions under simulated solar irradiation. The degradation kinetics followed a pseudo-first order reaction and monitored by headspace solid-phase microextraction (SPME) and gas chromatography (GC) with flame thermionic detection. The degradation of both insecticides was a fast process with half-lives varying between 1.0 and 12.2 min depending on the TiO2 concentration as well as on the structure of the compound. The generated transformation products formed during the process were extracted by SPME: (a) by direct immersion of the fiber in the filtered sample and (b) by exposing the fiber in the headspace. The intermediates were formed predominately via oxidation processes and were identified by gas chromatography and mass spectrometry (MS). (C) 2002 Elsevier Science B.V. All rights reserved.