Abstract:A new method based on membrane dialysis/high performance liquid chromatography-tandem mass spectrometry (MD/HPLC-MS/MS) was developed for the analysis of nine β-agonist residues (e.g., clenbuterol, ractopamine, salbutamol) in livestock products. The samples were extracted with ammonium acetate buffer, enzymolyzed by β-glucuronidase/arylsulfatase, and purified with a standard-grade regenerated cellulose dialysis membrane (RC, MWCO: 1000 D). The residues of β-agonists were infiltrated through the membrane into the dialysis solution, which was extracted with cyclohexane-ethyl acetate (4:1). The β-agonists were separated with Waters Xbridge C18 columns using a gradient elution with 0.1% formic acid-acetonitrile as the mobile phase. The β-agonists were detected by positive electrospray ionization (ESI+) in the multiple reaction monitoring (MRM) mode, and the quantification analysis was performed by an external standard method. The results showed that the nine β-agonists had good linearities in the range from 0.5 μg/kg to 10 μg/kg. The limits of quantitation for all β-agonists were 0.5 μg/kg. The recoveries of these analytes varied from 72.5% to 92.6% at the spiked levels of 0.5 μg/kg, 1.0 μg/kg, and 2.5 μg/kg. The relative standard deviation of the method varied from 4.1% to 12.7% (n = 6). The method was based on membrane dialysis and expensive solid-phase extraction cartridges were not required. Thus, this method is economical, highly sensitive, and suitable for the determination of the nine β-agonists residues in livestock products.
