Liquid chromatography-tandem mass spectrometry as a fast and simple method for the determination of several antibiotics in different aqueous matrices

Abstract

Environmental contextAntibiotic residues released to the environment could influence the selection of antibiotic-resistant bacteria and hence their spread within the aquatic environment. We report a multi-method approach for determining 47 antibiotics in wastewater, surface water, drinking water and groundwater. The method provides a rapid screening of water samples for common antibiotics that have the potential to alter natural bacterial populations. AbstractA simple and rapid liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) method for the determination of 47 different antibiotics in water samples was developed. A straightforward sample preparation of aqueous samples could be established using a simple dilution step with a mixture of water and acetonitrile (+ 0.8gL−1 ethylenediaminetetraacetic acid (EDTA)), subsequent filtration through a hydrophilised polytetrafluoroethylene (H-PTFE) syringe filter and a subsequent direct injection. The multi-analyte method presented includes substances from eleven classes of antibiotics (penicillins, cephalosporins, carbapenems, macrolide antibiotics, lincosamides, fluoroquinolones, tetracyclines, sulfonamides, glycopeptid antibiotics, oxazolidinones and nitroimidazoles). The method is characterised by a typical dynamic range from 0.01µgL−1 to a maximum of 5µgL−1, with good linearity regression coefficients (r2>0.99) and suitable recovery rates (generally from 65±13% to 117±5%) in spiked drinking water, surface water, groundwater and simulated treated wastewater. Suitable limits of quantification between 3.3ngL−1 and 190ngL−1 could be obtained, which are sufficient to determine low levels of antibiotic residues in the aquatic environment. The efficiency of the developed method was tested by analysing the residual concentrations of antibiotics in a small creek in Germany (‘Swistbach’). Sulfamethoxazole in combination with trimethoprim could be detected frequently, with calculated detection frequencies of 94–100% and 29–47%, as well as macrolide antibiotics (azithromycin (50–60%), clarithromycin (82–94%), clindamycin (88–100%) and erythromycin (41–53%). The determined concentrations were in a range between 0.01µgL−1 and 0.43µgL−1 downstream of the municipal wastewater treatment plants, whereas no antibiotics could be detected upstream.