Automatised on-line SPE-chiral LC-MS/MS method for the enantiomeric determination of main fluoroquinolones and their metabolites in environmental water samples

Fluoroquinolones are antibiotics of significant environmental concern their extended use not only in human medicine but also in veterinary medicine and not only as therapeutic agents but also to promote livestock growth and in aquaculture. Some fluoroquinolones and their metabolites are chiral compounds. Therefore, for a proper environmental risk assessment, enantioselective analytical methods are required. In this work, an analytical method has been developed and validated for the first time automatised enantioselective determination of environmental significant fluoroquinolones and their metabolites in wastewater and surface water samples. Target fluoroquinolones were selected by considering their extended use in human (ciprofloxacin and ofloxacin) and veterinary (flumequine) medicine. The analytical method was based on on-line solid-phase extraction-chiral liquid chromatography-tandem mass spectrometry. Analysis, including sample extraction and chiral LC-MS/MS determination, was carried out in just 14 min. The method was validated for its application to surface water and effluent and influent wastewater. Accuracy values were in the range from 61.4 to 122 % in wastewater and from 73.4 to 119 % in surface water. Precision, expressed as relative standard deviation, was lower than 13.6 % for all the compounds and sample matrices. Method quantification limits were in the range from 0.2 to 50 ng/L for all the compounds in wastewater and surface water. Method application to wastewater and surface water samples revealed the enantioselective transformation of LEV into (R)-OFL in surface water and the prevalence of OH-FLU D2 with respect to OH-FLU D1 in influent wastewater.