The determination of β-agonist residues in bovine tissues using liquid chromatography tandem mass spectrometry.

We aimed to develop a rapid, simple, and reproducible method based on liquid chromatography/tandem mass spectrometry (LC-MS/MS) to analyze β-agonist residues (clenbuterol, zilpaterol, ractopamine, and isoxsuprine) in bovine tissues. The method was validated in accordance with the European Council Decision 2002/657/EC. The samples were homogenized, and then 10 mL of an acetate buffer were added to a 5-g sample. The sample was then centrifuged at 12,000 rpm and filtered. Two-molar sodium hydroxide was added to adjust pH, and centrifuged again. The extract was filtered through a solid phase extraction column. The residue was redissolved in 250 μL of acetonitrile and then subjected to LC-MS/MS. The separation was done on a C18 column. The mobile phase consisted of 0.1% formic acid in deionized water and 0.1% formic acid in methanol. The mean recoveries of β-agonists were in the range of 84.3-119.1% with RSDs of 0.683-4.05%. Decision limits and detection capabilities of the analytes upon the method ranged from 0.0960 to 4.9349 μg/kg and from 0.0983 to 5.0715, respectively. This method was used to detect four β-agonists in 100 bovine muscle, 100 liver, and 100 kidney tissues from a slaughterhouse. No residue was found above the maximum residue limit level.