Determination of Tetracyclines and Their Epimers in Agricultural Soil Fertilized with Swine Manure b

A rapid,sensitive and specific ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS) method was developed for the analysis of tetracycline antibiotics,including tetracycline (TC),oxytetracycline (OTC),chlortetracycline (CTC) and their 4-epimers (4-epiTCs) in agricultural soil fertilized with swine manure.Soil samples were extracted and cleaned-up with 10 mL EDTA-Mcllvaine buffer solution (pH 4.0),then cleaned-up and pre-concentrated using the Oasis MAX cartridge and then eluted with 1 mL solution by mixing formic acid,methanol and water at a ratio of 2∶15∶83 (v/v/v).The purified samples were separated by an ACQUITY UPLC BEH C18 column using acetonitrile and water containing 0.1％ formic acid mobile phase and detected by a single quadrupole MS.The limits of detection for the soil extraction method (LODsoil) ranged from 0.6-2.5 μg kg-1 with recoveries from 23.3-159.2％.Finally,the method was applied to an agricultural field in an area with intensive pig-fattening fanning.Tetracyclines were detected in soil from 2.8 to 42.4 μg kg-1 soil.These results demonstrate that soil from swine farms can become severely contaminated with tetracycline antibiotics and their metabolites.