title: Degradation of fluoroquinolone antibiotics and identification of metabolites/transformation products by liquid chromatography-tandem mass spectrometry.
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 10 mg L(-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) 3 μm column. The validated method demonstrated good selectivity, linearity (r(2)>0.999), intra-day and inter-day precisions (RSD<2.74%) and accuracy. The quantification limits were 5 μg L(-1) for OFL, NOR and CPF and 20 μg L(-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.
authors.affiliation: CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Rua Central de Gandra, 1317, 4585-116 Gandra PRD, Portugal; CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal.
authors.forename: Alexandra S
authors.initials: AS
authors.lastname: Maia
authors.affiliation: CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Rua Central de Gandra, 1317, 4585-116 Gandra PRD, Portugal; CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal; Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Ribeiro
authors.affiliation: CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal; Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
authors.forename: Catarina L
authors.initials: CL
authors.lastname: Amorim
authors.affiliation: Departamento de Química, Universidade Federal de São Carlos, CP 676, 13560-970 São Carlos, SP, Brasil.
authors.forename: Juliana C
authors.initials: JC
authors.lastname: Barreiro
authors.affiliation: Departamento de Química, Universidade Federal de São Carlos, CP 676, 13560-970 São Carlos, SP, Brasil.
authors.forename: Quezia B
authors.initials: QB
authors.lastname: Cass
authors.affiliation: CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal.
authors.forename: Paula M L
authors.initials: PM
authors.lastname: Castro
authors.affiliation: CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Rua Central de Gandra, 1317, 4585-116 Gandra PRD, Portugal; Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal. Electronic address: elizabeth.tiritan@iscsn.cespu.pt.
authors.forename: Maria Elizabeth
authors.initials: ME
authors.lastname: Tiritan
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D001372:Aza Compounds / Q000737:chemistry / Q000378:metabolism; D001711:Biotransformation; D002853:Chromatography, Liquid / Q000379:methods*; D002939:Ciprofloxacin / Q000737:chemistry / Q000378:metabolism; D024841:Fluoroquinolones / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D000077266:Moxifloxacin; D009643:Norfloxacin / Q000737:chemistry / Q000378:metabolism; D015242:Ofloxacin / Q000737:chemistry / Q000378:metabolism; D010782:Photolysis; D011804:Quinolines / Q000737:chemistry / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; D011804:Quinolines; D002939:Ciprofloxacin; D015242:Ofloxacin; D009643:Norfloxacin; D000077266:Moxifloxacin
keywords: Biodegradation; Fluoroquinolones; Transformation products