Novel Stir Bar Array Sorptive Extraction Coupled With Gas Chromatography-Mass Spectrometry for Simultaneous Determination of Three β2-Agonist Residues in Pork

This study aimed to simultaneously determine three beta 2-agonists (clenbuterol, salbutamol, and ractopamine) in pork samples using novel stir bar array sorptive extraction coupled with gas chromatography-mass spectrometry. Pencil refill was employed as the substrate of stir, which was covered with carboxyl graphene sheets and polyluminol coating. The coating was simply prepared by electrochemical deposition of luminol at a voltage of 0-0.6 V. Then, an automatic device with the stir bar array for extraction was used. The conditions for the extraction were optimized. Under the optimum extraction conditions, with toluene as the extraction solvent, the extraction and desorption times were 20 min. A good linearity of three beta 2-agonists was obtained in the range of 0.5-100 ng g(-1) by gas chromatography-mass spectrometry detection. The recovery of clenbuterol, salbutamol, and ractopamine in spiked pork samples ranged from 88.7 to 93.2%, 85.5-94.2%, and 85.7-93.9%, respectively, with the relative standard deviations less than 10%. The detection limits were in the range of 0.022-0.091 ng g(-1) for pork samples. The extraction coating with high extraction capacity was simply fabricated by the electrochemical method, which could simplify the pretreatment procedures. Moreover, the array could extract several samples simultaneously and improve the pretreatment efficiency.