Wan Eric Chun-hong, Ho Clare, Sin Della Wai-mei, Wong Yiu-chung
Analytical and Advisory Services, Government Laboratory of the Hong Kong Special Administrative Region (HKSAR), Homantin Government Offices, Hong Kong, China.
Anal Bioanal Chem. 2006 May;385(1):181-8. doi: 10.1007/s00216-006-0325-5. Epub 2006 Mar 18.
Liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS) was applied to the determination of residual bacitracin A, colistin A, and colistin B in milk and animal tissue samples. Prior to instrumental analysis, samples were subjected to acid extraction followed by solid-phase cleanup using Strata-X cartridges. Mass spectral acquisitions were performed under selective multiple reaction monitoring (MRM) mode at m/z 199 and 670 from triply charged precursors of bacitracin A (m/z 475); m/z 385 and 379 from triply charged precursors of colistin A (m/z 391); and m/z 380 and 374 from triply charged precursors of colistin B (m/z 386). Method precision was evaluated from spike recovery of samples fortified at concentrations corresponding to 2/5 of the maximum residue limits (MRLs) for each of the analytes under study. Intra-day and inter-day variations were found to range from 90.9 to 104% with relative standard deviation (RSD) <6.5%, and from 90.1 to 106% with RSD <9.1%, respectively. Limits of quantification (LOQs) were defined as the spiking concentrations at 2/5 MRL, and limits of detection (LODs) were 10-47 microg kg(-1) for bacitracin A, 1-16 microg kg(-1) for colistin A, and 6-14 microg kg(-1) for colistin B in milk and animal tissues. The presented method has good precision and high sensitivity and was applied as a fast screening protocol and a quantitative tool for monitoring of the concerned polypeptides in foods as part of a surveillance program.
采用液相色谱-电喷雾电离串联质谱法（LC-MS/MS）测定牛奶和动物组织样品中的杆菌肽A、黏菌素A和黏菌素B残留量。在进行仪器分析之前，样品先进行酸提取，然后使用Strata-X柱进行固相净化。质谱采集在选择性多反应监测（MRM）模式下进行，杆菌肽A（m/z 475）的三重带电前体离子在m/z 199和670处监测；黏菌素A（m/z 391）的三重带电前体离子在m/z 385和379处监测；黏菌素B（m/z 386）的三重带电前体离子在m/z 380和374处监测。通过在对应于每种被测物最大残留限量（MRLs）的2/5浓度水平加标回收来评估方法的精密度。日内和日间变化分别为90.9%至104%，相对标准偏差（RSD）<6.5%；以及90.1%至106%，RSD<9.1%。定量限（LOQs）定义为2/5 MRL的加标浓度，牛奶和动物组织中杆菌肽A的检测限（LODs）为10 - 47 μg kg⁻¹，黏菌素A为1 - 16 μg kg⁻¹，黏菌素B为6 - 14 μg kg⁻¹。所提出的方法具有良好的精密度和高灵敏度，作为一种快速筛查方案和定量工具，用于作为监测计划一部分的食品中相关多肽的监测。
