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Photochemical Degradation of Marbofloxacin and Enrofloxacin in Natural Waters

2010; American Chemical Society; Volume: 44; Issue: 12 Linguagem: Inglês

10.1021/es100278n

1520-5851

Michela Sturini, Andrea Speltini, Federica Maraschi, Antonella Profumo, Luca Pretali, Elisa Fasani, Angelo Albini,

Antibiotic Resistance in Bacteria

The photochemical fate of Marbofloxacin (MAR) and Enrofloxacin (ENR), two Fluoroquinolones (FQs) largely used as veterinary bactericides known to be present in surface waters, was investigated in aqueous solution. The degradation of these pollutants (5−50 μg L−1 starting concentration) was complete in about 1 h by exposure to solar light (summer) and obeyed a first-order kinetics. The structure of the primary photoproducts was determined. Those from ENR arose through three paths, namely, oxidative degradation of the piperazine side-chain, reductive defluorination, and fluorine solvolysis. More heavily degraded products that had been previously reported were rationalized as secondary photoproducts from the present ones. As for MAR, this underwent homolytic cleavage of the tetrahydrooxadiazine moiety to give two quinolinols. All of the primary products were themselves degraded in about 1 h. The photoreactions rates were scarcely affected by Ca2+ (200 mg L−1), Mg2+ (30 mg L−1), Cl− (30 mg L−1), and humic acid (1 mg L−1), but increased in the presence of phosphate (20 mg L−1). The fastest degradation of ENR occurred at pH about 8 where the zwitterionic form was present, while in the case of MAR the cationic form was the most reactive.