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In many countries, ractopamine hydrochloride (RAC) is allowed to be used in animal production as a β-agonist, which is an energy repartitioning agent able to offer economic benefits such as increased muscle and decreased fat deposition, feed conversion improvement and an increase in average daily weight gain. However, some countries have banned its use and established strict traceability programmes because of pharmacological implications of β-agonist residues in meat products. In Brazil, commercial RAC is controlled (5-20 mg kg -1 ) and only added to pig diet during the last 28 days before slaughter. However, the control is more difficult when co-products, like meat and bone meal (MBM), which can be produced from RAC treated animals, are part of the feed composition. Therefore, a study was undertaken to evaluate the presence of RAC residue concentrations in urine and tissues of gilts (n = 40) in four dietary groups: 0%, 7%, 14% and 21% (w/w) of MBM-containing RAC (53.5 µg kg -1 ). The concentration of RAC residues in MBM, pig tissues and urine was determined by LC-MS. Low RAC concentrations were detected in muscle, kidney, liver and lungs (limit of detection = 0.15, 0.5, 0.5 and 1.0 µg kg -1 , respectively); however, no RAC residues were quantified above the limit of quantification (0.5, 2.5, 2.5 and 2.5 µg kg -1 , respectively). In urine, the RAC concentration remained below 1.35 µg L -1 . These data suggest that MBM (containing 53.5 µg kg -1 RAC) added to diet up to 21% (w/w) could hamper the trade where RAC is restricted or has zero-tolerance policy.

A QuEChERS method of ractopamine (RCT) residue detection in swine meat and bone meal (MBM) samples was demonstrated. Samples were hydrolyzed with protease and β-glucuronidase prior to QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction and clean-up. Samples were analyzed in a Liquid Chromatography (equipped with ACE 5 C18 column under gradient elution) coupled with a triple quadrupole mass spectrometer operating in positive electrospray ionization mode (using multiple reaction monitoring, MRM). The method was validated for its specificity, decision limit (CCα), detection capability (CCβ), recovery, repeatability, reproducibility, linearity, limits of detection (LODs), quantification (LOQs), and stability according to international guidelines (European Commission Decision 2002/657/EC). Recoveries ranged from 96.3 to 107.0%. Repeatability and reproducibility showed both RSD<5.7% and 3.1%, respectively. LODs and LOQs were 1.91 and 6.36 ppb, respectively. CCα and CCβ values were 1.91 and 2.37 ppb, respectively. RCT showed good stability for spiked samples and real samples when the concentration was higher, otherwise at lower concentration stability was lower. The proposed method can be successfully applied on a regular basis for the determination of RCT in MBM, demonstrating the usefulness of the method as a tool for compliance monitoring in regulatory laboratories., (Copyright © 2016 Elsevier B.V. All rights reserved.)