Exploring the aquatic photodegradation of two ionisable fluoroquinolone antibiotics - Gatifloxacin and balofloxacin: Degradation kinetics, photobyproducts and risk to the aquatic environment

The Science of the Total Environment
Linke GeZiwei Yao

Abstract

Fluoroquinolone antibiotics (FQs) are ubiquitous and ionisable in surface waters. Here we investigate gatifloxacin (GAT) and balofloxacin (BAL), two widely used FQs, and determine the photochemical reactivity of their respective dissociation species that arise at different pH to understand the relevance and pathways of phototransformation reactions. Simulated-sunlight experiments and matrix calculations showed that neutral forms (HFQs0) of the two antibiotics had the highest apparent photolytic efficiency and hydroxyl-radical oxidation reactivity. Based on the pH-dependent photochemical reactivities, the solar apparent photodegradation half-lives (t1/2) in sunlit surface waters ranged from 14.5-169min and was 1-2 orders of magnitude faster than hydroxyl-radical induced oxidation (t1/2=20.9-29.8h). The corresponding pathways were proposed based on the identification of key intermediates using HPLC-ESI-MS/MS. The apparent photodegradation induced defluorination, decarboxylation, and piperazinyl oxidation and rearrangement, whereas hydroxyl-radical oxidation caused hydroxylated defluorination and piperazinyl hydroxylation. The photomodified toxicity of GAT and BAL was examined using an Escherichia coli activity assay. E. coli acti...Continue Reading

Citations

Feb 28, 2019·Photochemical & Photobiological Sciences : Official Journal of the European Photochemistry Association and the European Society for Photobiology·B SulzbergerN D Paul
Feb 9, 2021·Chemosphere·Iván SciscenkoGilles Mailhot
May 1, 2021·Molecules : a Journal of Synthetic Chemistry and Natural Product Chemistry·Marwa El-AzazyHagar Morsy
Jan 27, 2019·Environment International·Mohit KumarPratyoosh Shukla
Apr 28, 2020·Ecotoxicology and Environmental Safety·Li-Jun ZhouQinglong L Wu

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