Development of a mutton powder certified reference material for the analysis of ractopamine

A novel matrix certified reference material (CRM) of ractopamine in mutton powder GBW 10169 was first developed. The incurred mutton obtained by orally administering ractopamine was lyophilized, mixed, dispensed and sterilized to prepare the CRM candidates. An optimized ultra-performance liquid chromatography tandem isotope dilution mass spectrometry (UPLC-ID-MS/MS) method was used for the characterization. The CRM characterization was carried out in nine laboratories in accordance with ISO Guide 35 requirements. The certified value of CRM was 10.4 mu g/kg with an expanded uncertainty of 1.2 mu g/kg (k = 2). The CRM was suf-ficiently homogeneous between and within bottles and stable up to 12 months at -20 degrees C and 9 days below 50 degrees C. The uncertainty was evaluated by combing the contributions from characterization, homogeneity and stability. Thus, the CRM can be used for quality control and method validation to ensure the accurate and reliable quantification of ractopamine residue in mutton.