Abstract: A method was developed for the determination of the residue of phenylethanolamine A in feeds by ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). The phenylethanolamine A in sample was extracted with phosphoric acid methanol solution. The extract was purified and concentrated by an MCX column. In the positive mode, an ultra-performance BEH C18 column (100 mm×2.1 mm, 1.7 μm) was used to separate the phenylethanolamine A, and the separation was carried out on a Waters UPLC system by using gradient elution with acetonitrile and 0.1%(v/v)formic acid aqueous solution as the mobile phases at a flow rate of 0.4 mL/min. The qualitative and quantitative analysis was carried out by multi-reaction monitoring (MRM) mode, in which the analyte was ionized by electrospray ionization interface (ESI). The results showed that, the calibration curve was linear in the range of 0.5~100 μg/kg (r﹥0.999), the limit of quantification (S/N ＞ 10) was 10 μg/kg, the recoveries ranged from 79.6% to 86.2%, and the relative standard deviations (RSDs) were between 3.1% and 6.7%. The real sample tests showed that the method is convenient and reliable.

Key words: feeds, phenylethanolamine A, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)