| A rapid liquid chromatography-tandem mass spectrometric(LC-MS/MS) method was developed for the determination of enramycin in swine liver.The swine liver samples were extracted twice with 0.1 mol/L hydrochloric acid solution-acetonitrile(3∶7,by volume),then purified by liquid-liquid extraction with ethyl acetate and hexane after centrifugation,and finally analyzed by LC-MS/MS after dilution with 0.1% formic acid solution.The separation was performed on an Acquity BEH C18 column(100 mm×2.1 mm，1.7 μm) with 0.1% formic acid solution-methanol as mobile phase by gradient elution.The LC-MS/MS analysis was in a positive electrospray ionization(ESI+) mode with multiple reaction monitoring(MRM) acquisition,and matrix matched external standard method was used for quantitation.Results showed that there existed good linear relationships for enramycin A and enramycin B in the range of 2.0-500 μg/L.The limits of detection for enramycin A and enramycin B were 3.0 and 4.0 μg/kg,and the limits of quantitation for them were 10 and 12 μg/kg,respectively.At the spiked levels of 15-60 μg/kg,the recoveries ranged from 80.8% to 90.3% with intra-assay relative standard deviations of 0.90%-4.5% and inter-assay relative standard deviations of 3.0%-4.3%.Compared with the other LC-MS/MS methods,the method is more suitable for the determination of enramycin in animal liver tissues due to its simplicity and reliability. |