Multi-Residual Analysis of 17 β₂-Agonists and β-Blockers in Milk by HPLC-MS/MS

A method for the determination of 17 β₂-agonists and β-blockers in milk was developed by solid-phase extraction(SPE) and high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS). The samples were extracted with acetontrile and cleaned with an Oasis MAX SPE cartridge, after protein precipitation with trichloracetate. The analytics were quantified by HPLC-ESI-MS/MS operating in positive multiple-reaction mode(MRM). Recoveries of 17 compounds range from 61.6 % to 134.3%, and the RSDs are less than 25%. LOD and LOQ of the analytics upon the method range from 0.024 to 3.960 μg kg^－1 and from 0.068 to 13.200 μg kg^－1.