Determination of Four beta(2)-Agonists in Meat, Liver and Kidney by GC-MS with Dual Internal Standards

A method is presented to quantitate four beta(2)-agonists (orciprenaline, clenbuterol, salbutamol and ractopamine) in meat, liver and kidney, by GC-MS, using dual internal standards, fenoterol and metoprolol. The procedure involves liquid-liquid extraction, followed by a solid phase clean-up step and derivatization. Mass spectral acquisition was done in selected ion monitoring mode to provide a high degree of sensitivity, achieving a limit of detection of 0.04-0.09 mu g kg(-1) and quantitation of 0.20-0.30 mu g kg(-1). The typical recoveries of analytes spiked at 10, 1 and 0.1 mu g kg(-1) were at 80.0-102.0, 77.6-90.7 and 52.0-87.4%, respectively.