LC/MS and LC/MS/MS Strategies for the Evaluation of Pesticide Intermediates Formed by Degradative Processes: Photo-Fenton Degradation of Diuron

Abstract

Transformation products (TPs) obtained from diuron under photo-Fenton pilot scale degradation process were evaluated using various high performance liquid chromatography systems with electrospray ionization and provided by different analyzers such as quadrupole, ion trap and time of flight. The base peaks obtained in all cases were the protonated molecules (M+H)+ and very similar fragmentation patterns were obtained in all cases by the different systems. The use of single quadrupole lead to the determination of structures based on the molecular weight and one additional fragment ion obtained by increase of the fragmentor voltage. The structures proposed in this way were related with suspected oxidative reactions as a consequence of the attack of the OH radicals generated. Ion trap allowed the confirmation of the structures proposed in this way were related with suspected oxidative reactions as a consequence of the attack of the OH radicals generated. Ion trap allowed the confirmation of the structures of suspected and unknowns compounds by applying multiple mass spectrometric analyses (MS2 and MS3). The application of TOF was relevant, in the determination of open ring structures that were only possible to identify by using accurate mass information. Furthermore additional parameters such as total organic carbon, organic ions and inorganic species were also evaluated to assess the proposed degradation pathway.