内标在LC-MS法生物样品分析中的相关问题探讨

Discussion about internal standards in LC-MS for bioanalysis

内标在LC-MS法生物样品定量分析时被广泛使用,它可以补偿检测过程中待测物在样品准备、色谱分离和信号响应等方面的损失或变化,使定量结果更加准确。选择一个合适的化合物做内标十分关键。采用内标法需关注诸多问题,如选择类似物还是稳定同位素内标,使用稳定同位素内标需要注意什么,内标浓度如何确定及如何评价未知浓度样品内标响应的变异。本文将对这些问题进行初步探讨。

Internal standards are widely used in LC-MS for quantitative analysis of biological samples, which can compensate for the loss or change in sample preparation, chromatographic separation and signal response. So it is very critical to choose a suitable compound as the internal standard. Which one should be chosen： structural analog or stable isotope-labeled compound？ What should be noted when using stable isotope- labeled compounds as internal standards？ How to determine the concentration of internal standard？ How to evaluate the variation of internal standard response with unknown sample concentration？ All these issues should be addressed when using internal standard method. This paper made a preliminary discussion on these issues.