A new methodology is proposed for ractopamine residue analysis in pork. It consists of enzyme-mediated digestion and deconjugation steps; modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction; and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In brief, the samples were digested with protease and then deconjugated with β-glucuronidase enzyme; they were then subjected to extraction and cleanup by QuEChERS and underwent sequential analysis by LC-MS/MS. The method performance was evaluated in accordance to the validation guidelines regulated by the Brazilian Ministry of Agriculture and Food Supply. The limit of detection was 0.15 μg/kg and limit of quantification was 0.5 μg/kg. When the method was applied to real samples, ractopamine residue was found in concentrations (up to 7.86 μg/kg) below international recommendation limits up to 10 μg/kg. The method is sensitive, accurate, quick, simple, and suitable for routine analysis; therefore, it is a monitoring tool that may be adopted by laboratories to achieve compliance levels.
Keywords: Hydrolysis; Liquid chromatography; Mass spectrometry; Method validation; Swine muscle; β-Agonist.