Determination of clenbuterol, ractopamine and zilpaterol in liver and urine by liquid chromatography tandem mass spectrometry

Beta-agonists have been misused as growth promoting agents in meat producing animals over 20 years. Clenbuterol (CLB) was the main beta-agonist substance used illegally for this purpose. But other beta-agonist substances have been developed to be used for zootechnical purposes, such as ractopamine (RCT), licensed for this application in the United States and currently zilpaterol (ZIL), licensed in South Africa and Mexico. However, these compounds are banned in the European Union (EU) Council Directive 96/22/EC. An analytical method able to identify these three beta-agonists by liquid chromatography tandem mass spectrometry (LC-MS-MS), after clean-up with mixed-mode SPE Bond Elut Certify cartridges (6 mL, 300 mg) was developed and validated according to the Commission Decision 2002/657/EC. Decision limit (CCα) ranged from 40 to 110 pg mL−1 and from 80 to 150 pg g−1 (ppt) for urine and liver, respectively. Detection capability (CCβ) ranged from 180 to 270 pg mL−1 and 270 to 520 pg g−1 (ppt) for urine and liver respectively. This method appeared suitable for the control of these beta-agonists residues in liver and urine.