Photolysis and photocatalysis of ibuprofen in aqueous medium : characterization of byproducts via liquid chromatography coupled to high-resolution mass spectrometry and assessment of their toxicities against Artemia Salina.

Abstract

The degradation of the pharmaceutical compound ibuprofen (IBP) in aqueous solution induced by direct photolysis (UV-A and UV-C radiation) and photocatalysis (TiO2/UV-A and TiO2/UV-C systems) was evaluated. Initially, we observed that whereas photocatalysis (both systems) and direct photolysis with UV-C radiation were able to cause an almost complete removal of IBP, the mineralization rates achieved for all the photodegradation processes were much smaller (the highest value being obtained for the TiO2/UV-C system: 37.7%), even after an exposure time as long as 120 min. Chemical structures for the byproducts formed under these oxidative conditions (11 of them were detected) were proposed based on the data from liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) analyses. Taking into account these results, an unprecedented route for the photodegradation of IBP could thus be proposed. Moreover, a fortunate result was achieved herein: tests against Artemia salina showed that the degradation products had no higher ecotoxicities than IBP, which possibly indicates that the photocatalytic (TiO2/UV-A and TiO2/UV-C systems) and photolytic (UV-C radiation) processes can be conveniently employed to deplete IBP in aqueous media.