Development and validation of a sensitive method for simultaneous determination of eight β₂-agonists in pork by ultrasonic-assisted extraction and liquid chromatography/tandem mass spectrometry.

A simple and sensitive ultrasonic-assisted extraction coupled with liquid chromatography-tandem quadrupole mass spectrometry was developed for the simultaneous determination of eight β2-agonists (i.e., phenylethanolamine, fenoterol, formoterol, clenbuterol, ractopamine, salbutamol, terbutaline and tulobuterol) in pork. The recovery rate of ultrasonic-assisted extraction was compared with that of enzymolysis. Results showed that ultrasonic-assisted extraction is a satisfactory method for the treatment of pork samples, yielding β2-agonist recovery rates of 82.0-114.0%. In contrast, most of the recovery rates obtained by enzymolysis were <80%. Linearities obtained ranged from 0.1 to 16.0 μg kg(-1) for terbutaline, formoterol, tulobuterol and phenylethanolamine, 0.2 to 16.0 μg kg(-1) for salbutamol, fenoterol and ractopamine, and 0.2 to 40.0 μg kg(-1) for clenbuterol. The correlation coefficients were >0.9945 for all analytes. The lower limits of quantification were between 0.086 and 0.20 μg kg(-1). The applicability of the proposed method for detecting and quantifying β2-agonists was demonstrated in the analysis of 50 pork samples.