Determination of Residues of 26 β_2-Agonists in Pork Liver by Reversed Phase High Performance Liquid Chromatography-Tandem Mass Spectrometry

A method for determination of residues of 26 β2-agonists in pork liver was developed using high performance liquid chromatography with tandem mass spectrometric( HPLC-MS /MS). After enzymatic hydrolysis with β-Glucuronidase /Arylsulfatase for 12 hours,the pH of sample solution was adjusted to 1 using perchloric acid for protein precipitation. The precipitate was extracted with 0. 1mol /L perchloric acid aqueous.The extracts in the above two steps were combined and adjusted to pH 4 for the solid phase extraction(MCX). And then the 26 β2-agonists residues in the extracts were separated on a reversed phase HPLC column using a gradient elution program of 0. 1% formic acid aqueous solution(A) and 0. 1% formic acid in acetonitrile solution(B). Multiple reaction monitoring( MRM) with positive polarity was selected to monitor qualitative and quantitative ion. Based on the optimized method,26 β2-agonists could be analyzed in 15 min.The recoveries ranged from 64. 0% to 112. 7% for the 26 kinds of β2-agonists residues with three spiked levels of 5,10 and 20 μg /kg. The relative standard deviations( RSDs) were less than 15. 2%. The limits of detection(LOD) for the 26 kinds of β2-agonists were 0. 15- 1. 35 μg /kg.