Degradation of fluoroquinolone antibiotics and identification of metabolites/transformation products by liquid chromatography-tandem mass spectrometry

Alexandra S. Maia, Ana R. Ribeiro, Catarina L. Amorim, Juliana C. Barreiro, Quezia B. Cass, Paula M. L. Castro, Maria Elizabeth Tiritan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

103 Citations (Scopus)

Abstract

Antibiotics are a therapeutic class widely found in environmental matrices and extensively studied due to its persistence and implications for multi-resistant bacteria development. This work presents an integrated approach of analytical multi-techniques on assessing biodegradation of fluorinated antibiotics at a laboratory-scale microcosmos to follow removal and formation of intermediate compounds. Degradation of four fluoroquinolone antibiotics, namely Ofloxacin (OFL), Norfloxacin (NOR), Ciprofloxacin (CPF) and Moxifloxacin (MOX), at 10mgL-1 using a mixed bacterial culture, was assessed for 60 days. The assays were followed by a developed and validated analytical method of LC with fluorescence detection (LC-FD) using a Luna Pentafluorophenyl (2) 3μm column. The validated method demonstrated good selectivity, linearity (r2>0.999), intra-day and inter-day precisions (RSD<2.74%) and accuracy. The quantification limits were 5μgL-1 for OFL, NOR and CPF and 20μgL-1 for MOX. The optimized conditions allowed picturing metabolites/transformation products formation and accumulation during the process, stating an incomplete mineralization, also shown by fluoride release. OFL and MOX presented the highest (98.3%) and the lowest (80.5%) extent of degradation after 19 days of assay, respectively. A representative number of samples was selected and analyzed by LC-MS/MS with triple quadrupole and the molecular formulas were confirmed by a quadruple time of flight analyzer (QqTOF). Most of the intermediates were already described as biodegradation and/or photodegradation products in different conditions; however unknown metabolites were also identified. The microbial consortium, even when exposed to high levels of FQ, presented high percentages of degradation, never reported before for these compounds.

Original languageEnglish
Pages (from-to)87-98
Number of pages12
JournalJournal of Chromatography A
Volume1333
DOIs
Publication statusPublished - 14 Mar 2014

Keywords

  • Biodegradation
  • Fluoroquinolones
  • Transformation products

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