A multi-residue method was developed for the simultaneous determination of 18 β-agonist residues( clenbuterol,ractopamine,penbutolol,tulobuterol,etc ) in feed by using QuEChERS sample preparation and high performance liquid chromatography-tandem mass spec-trometry(HPLC-MS / MS). The feed samples were dispersed by water,then the analytes were extracted with acetonitrile containing 4%(v / v)ammonia and cleaned up by QuEChERS method with 25 mg octadecylsilyl( C 18 )and 50 mg primary secondary amine( PSA)adsorbents. The separation of compounds was carried on an Agilent ZORBAX Eclipse XDB-C 18 column(50 mm× 4. 6 mm,1. 8 μm)by a gradient elution using methanol-0. 1%( v / v)formic acid aqueous solu-tion as mobile phase. The analytes were detected by tandem mass spectrometry under multiple reaction monitoring(MRM)mode with positive electrospray ionization( ESI +)and quantified by the matrix-matched external standard method. The results showed that the calibration curves of the 18 β-agonists were linear in the range of 5 - 200 μg / L with correlation coefficients of 0. 991 2-0. 999 5. The average recoveries of the 18 analytes at three spiked levels of 0. 05,0. 1 and 0. 5 mg / kg ranged from 78. 4% to 107. 1% with the relative standard deviations( RSDs)of 3. 5% -12. 3% . The limit of quantification( LOQ,S / N≥10)was 0. 05 mg / kg for each analyte . The developed method is simple and sensitive,and can be applied as a screen and confirmatory method for the analysis of β-agonists in feed.%建立了饲料中克仑特罗、莱克多巴胺、喷布特罗、妥布特罗等18种β-兴奋剂的 QuEChERS 结合高效液相色谱-串联质谱的检测方法。饲料样品加水分散后经4％（ v / v）氨水乙腈提取，加入25 mg 十八烷基硅烷（ C 18）和50 mg N-丙基乙二胺（PSA）吸附剂分散固相萃取净化后，以高效液相色谱-串联质谱进行定性和定量分析。采用 Agi-lent Zorbax Eclipse XDB-C 18（50 mm×4.6 mm，1.8μm）分析柱，以甲醇-0.1％（v / v）甲酸水溶液为流动相进行梯度洗脱，串联质谱在多反应监测（MRM）正离子模式下进行检测，基质外标法定量。结果表明，18种待测物在质量浓度为5~200μg / L 范围内线性关系良好，相关系数为0.9912~0.9995；在0.05、0.1、0.5 mg / kg 3个浓度加标水平下，饲料中18种β-兴奋剂的平均回收率为78.4％~107.1％，相对标准偏差（RSD）为3.5％~12.3％，定量限（以信噪比≥10计）均为0.05 mg / kg。该方法准确、灵敏，前处理简单，可作为饲料中克仑特罗等18种β-兴奋剂筛选和确认的检测方法。
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