Direct Photolysis of Tiapride in Water: Deep insights into Desulfonation Reaction

The use of antipsychotics is constantly increasing worldwide due to their employment in the treatment of bipolar disorder, schizophrenia, autism, depression and more. These compounds are not efficiently removed by the current wastewater treatment technologies and are therefore recognised as environmental concerns. Unravelling their chemical transformations in the water matrix is therefore of high importance. This study investigates the photodegradation of tiapride (TP), an atypical neuroleptic agent, focusing on its reactivity by direct photolysis. The results unveiled a remarkable inhibitory effect of oxygen on the photodegradation, which was furtherly explored by fluorescence spectroscopy and laser flash photolysis. The involvement of the triplet excited state of TP in the process was demonstrated. The structures of the main transformation products under various oxygenation conditions, identified by LC/ESI/MS(MS), were proposed together with the TP transformation pathways.