Determination of Zeranols in Milk Using Immunoaffinity Microextraction in a Packed Syringe and High Performance Liquid Chromatograph-Tandem Mass Spectrometry

Abstract:

This research prepared a selective adsorbent on the basis of SiO2 glass beads bound with zeranol monoclonal antibody and the method of immunoaffinity microextraction in a packed syringe and high performance liquid chromatograph-tandem mass spectrometry (IA-MEPS-LC-MS/MS) was further developed to detect six kinds of zeranols (ZERs) in milk. Milk samples were centrifuged, and the middle layer was extracted with IA-MEPS syringe and washed by ultra-pure water before eluted with methanol. The eluent was concentrated and then re-dissolved by mobile phase. Finally, the sample was detected by LC-MS/MS, separated on a C₁₈ column with the mobile phase of water and acetonitrile. Matrix-matched external standard method was used for quantification. The linearity of six ZERs was good within 0.1~100.0 ng/mL, and the correlation coefficient was 0.994 3~0.996 2. The average recoveries ranged from 50.40% to 68.34% at the addition level of 1 ng/g, the intra-day and the inter-day RSDs were 4.87%~17.64% and 7.04%~18.75%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of this method were 0.05 ng/g and 0.2 ng/g, respectively.