| Abstract
| - Ozonation of ciprofloxacin at different pH and H2O2 conditions is studied, and degradation intermediates and pathways are proposed based on HRMS identification.
- Degradation products formed during ozonation of an aqueous solution of the antibiotic ciprofloxacin in a bubble column are analyzed by HPLC-UV high-resolution mass spectrometry. Based on the identification of the reaction products, reaction pathways are proposed starting with (1) degradation at the piperazinyl substituent, (2) degradation at the quinolone moiety with formation of isatin analogues, and (3) degradation at the quinolone moiety with formation of anthranilic acid analogues. Unlike H2O2 addition (10 µM), pH (3, 7, and 10) strongly affects degradation product formation during ozonation. Degradation at the quinolone core is favored at pH 7. Addition of t-butanol, a hydroxyl radical scavenger, ruled out formation of isatin and anthranilic acid analogues. Because the carboxylic group and the keto group at the quinolone moiety are essential for antibacterial activity, degradation at pH 7 seems to be promising for reduction of bacterial resistance against quinolones in contaminated water.
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