Determination of β-Agonists and Chloramphenicol Residues in Pork by Subcritical Water Extraction and Liquid Chromatography-Tandem Mass Spectrometry

A liquid chromatography-tandem mass spectrometric(LC-MS/MS) method with subcritical water extraction was developed for the determination of β-agonists and chloramphenicol in pork.Enzymatic hydrolysis was firstly used during the preparation of pork,then the target compounds were extracted with subcritical water and cleaned up by C18.The LC separation was performed on an Agilent XDB-C18 column(4.6 mm×50 mm,1.8 μm).The veterinary drugs were determined by MS/MS in MRM mode and quantified by the matrix-matched internal standard method.The calibration curves showed good linearities in the ranges of 1.0-32.0 μg/L for salbutamol and ractopamine with quantitation limits(S/N10) of 0.5 ng/g and detection limits(S/N3)of 0.25 ng/g,and 0.2-6.4 μg/L for clenbuterol and chloramphenicol with quantitation limits(S/N10) of 0.1 ng/g and detection limits(S/N3)of 0.05 ng/g.The correlation coefficients were all larger than 0.99.The recoveries of veterinaries in pork at three spiked levels ranged from 79.2% to 113.6% with relative standard deviations(RSDs)of 3.2%-12.0%.The sensitivity,accuracy and precision of the method could meet the technical standard for veterinary drugs determination,and the method was suitable for the determination of β-agonists and chloramphenicol in pork.