The purpose of this study is to artificially produce degradation compounds similar to those formed in oxido/reductive environmental pathways by adopting a photocatalytic process as a model-system and, afterwards, to identify them water samples, beside parent compounds. We have studied the photocatalytic transformation of atenolol, 4-[2-hydroxy-3-[(1-methyl)amino]propoxyl]-benzeneacetamide, a cardio-selective β-blocking agent prescribed for the treatment of cardiac arrhythmias and hypertension under simulated solar irradiation using titanium dioxide as a photocatalyst, found in the Po river. The investigation has involved a kinetic study of the drug decomposition, the identification of intermediate compounds, the assessment of mineralization, as well as toxicity evaluation. HPLC coupled to HRMS via ESI interface demonstrate to be a powerful tool to identify and measure degradation products of the studied drugs. In beta-blocker drugs photocatalytic degradation, many oxidative potential metabolites were formed in the simulation model, beside some hydrolysis sub-products. 23 main species were identified within atenolol transformations. The intermediates were characterized by taking into account their chromatographic behavior and kinetics of evolution, coupled with the exact mass information, an accurate analysis of the MS and MSn spectra and a comparison with parent drugs fragmentation pathways. It has permitted to unequivocally discriminate the diverse isomers. According to our findings, a tentative degradation pathway is proposed for the photocatalytic degradation of atenolol. All these intermediates are easily degraded themselves and until 2h of irradiation there are no compound recognized to endure. Photomineralization of the substrate in terms of carbon mineralization and nitrogen release was rather a quick process (within 4 h), where the amino moiety is mainly transformed into NH4+ and in a little extent into NO3- ions (ratio 9:1). Subsequently we have applied the method to the identification and measurement of parent drugs and metabolic degradation products in water samples (urban drains, sewage treatment plants, freshwaters).
Drugs as new contaminants: photocatalytic degradation process as a tool to study environmental fate of β-blockers
CALZA, Paola;MEDANA, Claudio;PELIZZETTI, Ezio;BAIOCCHI, Claudio
2007-01-01
Abstract
The purpose of this study is to artificially produce degradation compounds similar to those formed in oxido/reductive environmental pathways by adopting a photocatalytic process as a model-system and, afterwards, to identify them water samples, beside parent compounds. We have studied the photocatalytic transformation of atenolol, 4-[2-hydroxy-3-[(1-methyl)amino]propoxyl]-benzeneacetamide, a cardio-selective β-blocking agent prescribed for the treatment of cardiac arrhythmias and hypertension under simulated solar irradiation using titanium dioxide as a photocatalyst, found in the Po river. The investigation has involved a kinetic study of the drug decomposition, the identification of intermediate compounds, the assessment of mineralization, as well as toxicity evaluation. HPLC coupled to HRMS via ESI interface demonstrate to be a powerful tool to identify and measure degradation products of the studied drugs. In beta-blocker drugs photocatalytic degradation, many oxidative potential metabolites were formed in the simulation model, beside some hydrolysis sub-products. 23 main species were identified within atenolol transformations. The intermediates were characterized by taking into account their chromatographic behavior and kinetics of evolution, coupled with the exact mass information, an accurate analysis of the MS and MSn spectra and a comparison with parent drugs fragmentation pathways. It has permitted to unequivocally discriminate the diverse isomers. According to our findings, a tentative degradation pathway is proposed for the photocatalytic degradation of atenolol. All these intermediates are easily degraded themselves and until 2h of irradiation there are no compound recognized to endure. Photomineralization of the substrate in terms of carbon mineralization and nitrogen release was rather a quick process (within 4 h), where the amino moiety is mainly transformed into NH4+ and in a little extent into NO3- ions (ratio 9:1). Subsequently we have applied the method to the identification and measurement of parent drugs and metabolic degradation products in water samples (urban drains, sewage treatment plants, freshwaters).
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