Analysis of small molecule compounds in complex mixture system by LC-MS

It has been a challenging task of analytical chemistry to qualitatively and quantitatively analyze the diverse compounds in the complex mixture. Liquid chromatography-mass spectroscopy (LC-MS), especially, ultra-high performance liquid chromatography (UPLC) coupled with high resolution mass spectrometry (HRMS), is a powerful tool for the analysis of complex samples. UPLC can greatly enhance the ability and efficiency of chromatographic separation. On the other hand, HRMS can provide more precise molecular weight and can thus improve the reliability and accuracy of qualitative and quantitative analysis. In this paper, we summarized the application of LC-MS technology to analysis of small molecule compounds in typical complex mixtures (urine, blood, cell metabolites and natural product extracts), concentrating on sample preparation, data acquisition, data (pre)processing, qualitative and quantitative analysis, multivariate analysis. Furthermore, technical challenges and developments in the analysis of complex samples by LC-MS were summarized and prospected.