title: Kinetics and degradation pathways of photolytic and photocatalytic oxidation of the anthelmintic drug praziquantel.
abstract: In this study, an anthelmintic drug, praziquantel(PZQ), was degraded using the direct photolysis, photocatalysis, and oxidation processes including UV radiation, TiO2film, and hydrogen peroxide. The photolytic degradation with predominant wavelengths of 185/254nm (UV-C) proved to be more efficient with a half-life of 3.13min compared to the radiation of 365nm (UV-A) where the degradation did not occur. In order to enhance the rate of PZQ photolytic degradation, H2O2was added, which resulted in two to three times higher degradation rates. In the photocatalytic degradation, TiO2film was used as catalyst. The degradation was ten times faster in the photocatalytic experiments where UV-C light (k=0.2390min-1) was used than in those with UV-A (k=0.0201min-1). Comparing the results from all performed experiments it can be concluded that the UV-C/TiO2/H2O2process yielded the highest degradation rate and complete degradation of PZQ was obtained in less than 7min. The degradation of PZQ followed the first order kinetics in all the experiments. The photo degradation was inhibited in the presence of methanol. The degradation pathways and the structural formulae of five degradation products (m/z 273, 269, 189, 147, 132) were proposed based on the liquid chromatography tandem mass spectrometry analysis.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Croatia. Electronic address: mzrncic@fkit.hr.
authors.forename: Mirta
authors.initials: M
authors.lastname: Čizmić
authors.affiliation: Department of Energy, Power Engineering and Environment, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia. Electronic address: davor.ljubas@fsb.hr.
authors.forename: Davor
authors.initials: D
authors.lastname: Ljubas
authors.affiliation: Department of Materials, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia.
authors.forename: Lidija
authors.initials: L
authors.lastname: Ćurković
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Croatia.
authors.forename: Irena
authors.initials: I
authors.lastname: Škorić
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Croatia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Babić
mesh_terms: D000871:Anthelmintics / Q000737:chemistry* / Q000528:radiation effects; D006207:Half-Life; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D010782:Photolysis; D011223:Praziquantel / Q000737:chemistry* / Q000528:radiation effects; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D000871:Anthelmintics; C009495:titanium dioxide; D011223:Praziquantel; D014025:Titanium
keywords: Pharmaceuticals; Photodegradation pathway; Photolysis and photocatalysis; Praziquantel; Titanium dioxide film