Determination of Four Kinds of β-Agonists in Swine Urine by Molecularly Imprinted Solid Phase Extraction Followed Gas Chromatography Coupled Mass Spectrometry

A simple and rapid method for the determination of beta-agonists including Clorprenaline, Mabuterol, clenbuterol and ractopamine in swine urine by using molecular imprinted solid phase extraction followed with gas chromatography-mass spectrometry has been developed. 4 beta-Agonists in swine urine were concentrated and cleaned-up by using molecularly imprinted polymer (MIP) solid phase extraction cartridge, the comparison study of clean up effect for the MIP and common solid phase extraction cartridge was carried out. Then the purified sample was derivatized by using N, O-bis (trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% trimethylchlorosilane (TMCS) and were determined by gas chromatography-mass spectrometry(selected ion mode). Under the optimized conditions, there is a good linear correlation (the calibration coefficient is above 0.99) between the ratio of peak areas and the concentration of beta-agonists in the range of 5-100 mu g/L. the limit of quantitative (LOQ) is 0.5 mu g/L for ractopamine and 0.2 mu g/L for other beta-agonists in swine urine samples, the recoveries of different quantities of the beta-agonists spiked in swine urine are between 75.1% and 97.5%, the relative standard deviations (RSD) are below 10%. The developing method was applied to the determination of clenbuterol and ractopamine in real urine samples, the precision of the results is good, the manipulation of the developed method is simple and fast comparing to other methods.