The presence of drug residues in the environment, therapeutic, veterinary and illicit drugs, has recently become quite alarming and monitoring of pharmacologically active compounds is more and more necessary. The purpose of this study is to artificially produce degradation compounds similar to those formed in oxido/reductive metabolic and environmental pathways by adopting a photocatalytic process as a model-system and, afterwards, to characterize them by multiple stage mass spectrometry, using a high resolution ion trap (LTQ-Orbitrap). Ofloxacin and Ciprofloxacin are antibacterial of popular use and were chosen to study their presence in the environment. Liquid chromatography appears the best technique for direct analysis of these samples (neither derivatization nor complex extraction procedure for polar compounds), together with an high resolution MSn detection that empowers diagnostic identification and metabolites characterization. Heterogeneous photocatalysis experiments were performed under simulated solar light adopting TiO2 as photocatalyst. Solar light simulation was obtained using a 1500 W xenon lamp, at room temperature. LC-MS analysis were accomplished on a LTQ-Orbitrap instrument, with an electrospray interface. Chromatographic separation were achieved on C18 reversed phase columns. Degradation products identification has been performed acquiring MSn spectra at 60,000 resolution, in order to have elemental composition confirmation. Under these conditions experimental uncertainty was < 5 ppm. Toxicity of degradation products was evaluated in vitro and a significant correlation was found between maximum concentration of organic intermediates and toxicity. 10 intermediates were hypothesized in the case of ciprofloxacin and 12 in the case of ofloxacin.
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