title: Ion trap tandem mass spectrometry study of dexamethasone transformation products on light activated TiO2 surface.
abstract: The photocatalytic transformation of dexamethasone and the formation of its intermediate compounds have been studied using titanium dioxide as a photocatalyst. The degradation of dexamethasone occurs easily through the formation of several hydroxy derivatives whose characterization has been made by HPLC/MS/MS. Even if both oxidative and reductive processes can be operating, only oxidative products have been identified in air saturated aqueous suspensions. A pattern of reaction pathways accounting for the observed intermediates is proposed. The obtained experimental evidence may be rationalized postulating the existence of a double initial mechanism. A single oxidation step resulting from the attack by one *OH radical leading to the formation of five hydroxy-derivatives and a concomitant attack involving two *OH radicals leading to the hydroxylation of the quinoid moiety of the molecule.
authors.affiliation: Dipartimento di Chimica Analitica, Università di Torino, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Calza
authors.forename: E
authors.initials: E
authors.lastname: Pelizzetti
authors.forename: M
authors.initials: M
authors.lastname: Brussino
authors.forename: C
authors.initials: C
authors.lastname: Baiocchi
mesh_terms: D002853:Chromatography, Liquid; D003907:Dexamethasone / Q000737:chemistry* / Q000528:radiation effects; D008401:Gas Chromatography-Mass Spectrometry; D007202:Indicators and Reagents; D008027:Light; D013058:Mass Spectrometry; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry; D014025:Titanium
chemical_list: D007202:Indicators and Reagents; C009495:titanium dioxide; D003907:Dexamethasone; D014025:Titanium; D010100:Oxygen