RÉSUMÉ
A liquid chromatography-tandem mass spectrometry(LC-MS/MS)method was developed for determination of three kinds of β-agonists(Clenbuterol(CL),Ractopamine(RAC)and Salbutamol(SAL))residues in animal liver samples.The liver sample homogenates were extracted with organic solvent,followed by clean-up using the automatic magnetic solid-phase extraction(MSPE),and then analyzed using LC-MS/MS.The results showed that the magnetic mixed-mode cation exchange adsorbent(M-MCX)exhibited 34%higher adsorption capacity than the conventional mixed-mode cation exchange(MCX)column.Furthermore,the clean-up was conducted by using an automatic MSPE device,and 8 samples could be simultaneously treated within 30 min.The limits of detection(LOD)were 0.01-0.1 μg/kg,the average recoveries ranged from 88.2%to 110.5%,and the relative standard deviations(RSDs)were in range of 2.9%-10.3%at three spiked levels for the three kinds of β-agonists.Compared with the traditional SPE technique,the present method had many advantages such as simple operation,rapidity and high efficiency,which was suitable for high-throughput and automatic detection of residues in routine analysis.