| Abstract
| - Aqueous solutions of Pyrimethanil, as technical gradeproduct (TP), with 98.2% purity, and commercial formulation(CF), containing 40% (w/v) of Pyrimethanil, were submittedto photocatalytic degradation under sunlight in thepresence of TiO2 as catalyst in a preindustrial pilot plant.Complete Pyrimethanil degradation was achieved afterca. 230 min of irradiation, in both TP and CF, but totalmineralization was not observed, as was demonstrated bythe TOC values of 3−4 mg/L, measured at the end of theexperiments (907 min). A qualitative and quantitative studyof the degradation products (DPs) generated during theprocess was performed by GC-MS, using EI and CI as ionizationmodes, and by LC-API-MS, using Atmospheric PressureChemical Ionization (APCI) and Electrospray (ES) interfacingtechniques. Up to 22 compounds could be detected asdegradation intermediates. To evaluate the extractionefficiency of these DPs from the aqueous solution, speciallyfor the more polar intermediates, a recovery study wasperformed with Pyrimethanil and seven of the commerciallyavailable DPs. Liquid−liquid extraction (LLE) and solid-phase extraction (SPE), with different sorbents, werecompared. A SPE method using Lichrolut-EN cartridgeswas selected as the most adequate, but recoveries ≤60%were obtained for four of the DPs studied (aniline,formamide, 1,3-benzenediol, and 4,6-dimethyl-2-pyrimidinamine). Structure identification of DPs allowed us to proposetwo main routes in the degradation process. One routeinvolves the attack of hydroxyl radicals to the pyrimidineand benzene rings with further rings opening and the otherone corresponds to a photoinduced hydrolysis of themolecule by the amine group bonds.
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