Multi-Residue Determination of 7 β-Agonists in Liver and Meat Using Gas Chromatography-Mass Spectrometry

A robust and sensitive methodology, utilizing GC-MS, for the identification and quantitation of seven beta-agonist residues (mabuterol, clenbuterol, brombuterol, mapenterol, clenpenterol, clenproperol, and clencyclohexerol), in liver and meat samples, is described. Different extraction procedures, followed by GC/MS measurement, were tested and compared in order to achieve optimum extraction conditions and eliminate matrix effects. The optimized method consisted of consecutive extractions with hydrochloric tris(hydroxymethyl)aminomethane (TRIS-HCl) and tert-butyl-methyl ether (TBME), defatting with hexane and solid-phase extraction (SPE) with C18 cartridges. Ie,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) was used as a derivatization agent and the GC-EI-MS determination was performed using a MDN-5S capillary column in single-ion monitoring (SIM) acquisition mode. The method was validated according to the Commission Decision 2002/657/EC, fulfilling all the EU criteria. Quantification was performed via internal standard calibration using deuterated analogs of the compounds. Recoveries ranged from 83 to 118% (mabuterol at concentration levels of 2.0 and 1.5 mu g kg(-1), respectively) and precision, expressed as %relative standard deviation (% RSD), was in every case lower than the % RSDs obtained from Horwitz equation. The obtained decision limit (CC alpha) and detection capability (CC beta) values varied from 0.21 ng g(-1) (clenbuterol) to 0.49 ng g(-1) (clenproperol, clencyclohexerol) and from 0.60 (mapenterol) to 0.69 ng g(-1) (clenpenterol), respectively.