Quantitative analysis of clenbuterol in meat products using liquid chromatography-electrospray ionisation tandem mass spectrometry

A method is presented that allows quantitation of clenbuterol in meat and l iver products at the ng/kg level by liquid chromatography-electrospray ioni sation tandem mass spectrometry (LC-ESIMS-MS) using a stable isotopically l abeled internal standard. The practical procedure involves acid extraction followed by two solid-phase clean-up steps with C-18 and strong cation-exch ange (SCX) resins. The typical recovery of the analyte spiked at 0.4 mu g/k g in meat and liver samples was at 63+/-7%. Mass spectral acquisition was d one in multiple reaction monitoring (MRM) to provide a high degree of sensi tivity, achieving a limit of detection and quantitation at 10 and 15 ng/kg, respectively. Two precursor ions at m/z 277 and 279, corresponding to the characteristic isotopic cluster of the two chlorine atoms of clenbuterol, w ere monitored by LC-ESIMS-MS to provide unambiguous identity of the analyte . Samples of meat and liver of various origins with either incurred residue s or spiked with known amounts of clenbuterol were used to validate the met hod. (C) 1999 Elsevier Science B.V. All rights reserved.