Simultaneous Determination of 19 Antibiotics in Environmental Water Samples Using Solid Phase Extraction-Ultra Pressure Liquid Chromatography Coupled with Tandem Mass Spectrometry

A solid phase extraction and liquid chromatography coupled with tandem mass spectrometric(SPE/LC-MS/MS) method was established for the simultaneous determination of 19 antibiotics,including tetracyclines,sulfonamides,macrolides,quinolones and β-lactam antibiotics,in water samples up to the concentration range of ng/L level.13C-caffeine was selected as the internal standard.Samples were acidified and extracted through a hydrophilic-lipophilic balance(HLB) cartridge.The extract was separated on a reverse phase column using methanol-0.1% formic acid as mobile phase.The antibiotics were quantified with the internal standard method under multiple reactions monitoring(MRM) mode with an orthogonal electrospray ionization source(ESI+).The SPE conditions and LC-MS/MS parameters were optimized.Under the optimized conditions,the calibration curves of 19 antibiotics were linear in the range of 0.5-1 000 μg/L with limits of quantitation(S/N=10,concentrated by 1 000 fold) of 0.1-0.5 ng/L.The mean recoveries of 19 antibiotics from water matrices at two spiked level of 20 ng/L and 100 ng/L were in the ranges of 75%-125% and 77%-132%,with relative standard deviations of 1.7%-6.9% and 0.9%-6.5%,respectively.The results also showed that the Huangpu River was polluted by antibiotics,in which fifteen antibiotics were detected with the concentrations of 13.0-56.9 ng/L for tetracyclines,12.2-103.4 ng/L for sulfonamides,53.8-84.8 ng/L for macrolides,3.1-26.2 ng/L for quinolones and 16.5-181.6 ng/L for β-lactams,respectively.