RESUMO
A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) method was established for the determination of fifteen beta-agonists (clenbuterol, ractopamine, salbutamol, cimaterol, mabuterol, tulobuterol, bambuterol, mapenterol, cimbuterol, zilpaterol, formoterol, clorprenaline, terbutaline, penbutolol and brombuterol) in animal urine. Perchloric acid solution was used to acidify the sample and precipitate protein in the sample. The sample was purified and concentrated by an HLB mini-column. The separation of the beta-agonist was performed on an Agilent 1100 HPLC system with a Eclipse XDB-C18 column by using gradient elution with methanol and water (containing 0.1% (v/v) formic acid) as the mobile phases at a flow rate of 1 mL/min. Qualitative and quantitative analysis of the fifteen beta-agonists, which were ionized by electrospray ionization interface (ESI), were carried out in multiple reaction monitoring (MRM) mode with API 4000 tandem mass spectrometry. The calibration curves showed good linearity in the mass concentration range of 0.25 - 20 microg/L with the correlation coefficients r > or = 0.999 5. The recoveries of the fifteen beta-agonists ranged from 62.1% to 107% at the spiked levels of 0.25, 1.0 and 10 microg/L. The relative standard deviations (n = 10) were between 3.5% and 9.9%. The limits of quantification (S/N > 10) were 0.25 microg/L for all the analytes. This method is simple, rapid, sensitive and accurate.