Simultaneous Determination of Ractopamine, Chloramphenicol, and Zeranols in Animal-Originated Foods by LC-MS/MS Analysis with Immunoaffinity Clean-up Column

A novel analytical method employing immunoaffinity column (IAC) clean-up coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of ractopamine, chloramphenicol, and zeranols (α-zearalanol, β-zearalanol, zearalanone, α-zearalenol, β-zearalenol, and zearalenone) in animal-originated foods. The sample was first digested by β-glucuronidase/sulfatase and then extracted with ethyl acetate-diethyl ether (9:1, v/v). The extracted solution was evaporated to dryness and then the residue was dissolved by 2 mL of 50% acetonitrile solution. After filtration, 1 mL filtrate was diluted to 10 mL with PBS. The reconstituted solution was cleaned up with immunoaffinity column and then analyzed by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The established method was shown to be sensitive efficient and reliable as indicated by the linearity (r2 ≥ 0.9994), precision (RSD ≤ 1.7%), average recovery (72.3–103.2%), and the limit of detection (0.05–0.10 μg/kg). The method can be used for determination of trace residues of ractopamine, chloramphenicol, and zeranols in animal-originated foods.