Simultaneous determination of human and veterinary antibiotics in various environmental matrices by rapid resolution liquid chromatography–electrospray ionization tandem mass spectrometry

A robust and sensitive analytical method is presented in which 11 classes of antibiotics are simultaneously extracted and determined in surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge. Water samples with different volumes were adjusted to pH 3, added with 0.2g Na₂EDTA and then extracted using Oasis hydrophilic-lipophilic balance (HLB) cartridges. Extraction of solid samples was carried out by a combination of ultrasonic and vortex mixing using a mixture of acetonitrile and citric buffer at pH 3 as the extraction solution. The extracts of the solid samples were then cleaned-up by a tandem solid phase extraction (SPE) method using a strong anion exchange cartridge (SAX) and a HLB cartridge, followed by analysis using rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) equipped with electrospray ionization source. Among the 50 target compounds, the recoveries in the range of 50-150% were obtained for 39, 40, 36, 40, 38, 33 and 36 antibiotics in the spiked samples of surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge with three concentrations, respectively. Method quantification limits (MQLs) for the target compounds (except sulfaguanidine and sulfanilamide) were in the range of 0.52-5.88 ng/L, 2.36-65.8 ng/L, 1.73-20 ng/L, 1.42-9.52 ng/L, 0.64-6.67 ng/g (except bacitracin and cloxacillin), 1.33-17.4 ng/g (except salinomycin, narasin, monensin, cloxacillin and novobiocin) and 1.50-28.6 ng/g (except salinomycin, narasin, monensin and cloxacillin) in surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge, respectively. The developed analytical method was successfully applied in the determination of target compounds in wastewater and sludge samples from Huiyang wastewater treatment plants, and in ground water, lagoon wastewater, manure and sediment collected from a pig farm, in South China.