Determination of five β 2 -agonist residues in pork by ultra-high performance liquid chromatography-tandem mass spectrometry with molecularly imprinted solid phase extraction

An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method with molecularly imprinted solid phase extraction for the determination of five β2-gonists residues in pork has been developed. After the sample preparation, the ammonium acetate/acetic acid buffer was added, followed by the internal standard and β-glucuronidase/arylsulfatase enzyme. The solution was incubated at 55 °C for 2 h. After adjusting the pH of the solution, it was purified by a molecularly imprinted solid phase extraction column, then analyzed on a BEH C18 column with methanol-0.1% (v/v) formic acid aqueous solution as the mobile phases in gradient elution mode. The MS/MS analysis was in positive ion mode and multiple reaction monitoring mode. The analytes were quantified by the internal standard method. The limits of detection (LODs, S/N = 3) and the limits of quantification (LOQs, S/N = 10) were 0.005-0.009 µg/kg and 0.015-0.025 µg/kg, respectively. In the range of 0-10 µg/kg, the correlation coefficients of linear calibration curves were not less than 0.993 3. At the spiked levels of 0.25, 1.0 and 5.0 µg/kg, the recoveries were 80.4%-92.9% with the relative standard deviations of 1.3%-6.3%. The method is of high sensitivity, good reproducibility, high recovery, and is useful for the simultaneous determination of multiple β2-agonists residues.