Chemical Isotope Labeling LC-MS for Universal Urine Metabolomics

Abstract

Metabolomics refers to the characterization and quantification of small molecule metabolic products in a biological specimen. It is an emerging and evolving science studying the practice of precious medicine. Metabolomics study has been used to understand individual variations influenced by both genetic and environmental factors. Thus, measurement of metabolites has played an important role in clinical practice since the concept was introduced. In order to provide qualitative and quantitative information with high metabolite coverage, chemical isotope labeling (CIL) method has been developed. CIL is able to target different submetabolomes by adding isotope tags to improve separation, sensitivity and capability of relative quantification. This “divide and conquer” technology simplifies the platform of metabolomics study and promotes analytical performance of metabolites. My research focuses on utilizing CIL LC-MS approaches to profile amine/phenol submetabolomes to evaluate matrix effects in universal urine metabolome standard. In the first part of this thesis, CIL LC-MS was used to investigate the effect of urine sample matrix on metabolome analysis by comparing the absolute concentrations of selected metabolites with concentrations from external standards. The extent of matrix effects on labeling was evaluated by comparison of samples at different concentrations that were labeled using the same protocol. In the second part, CIL LC-MS was used to profile the amine and phenol submetabolome of universal urine metabolome standard. Matrix effects for a large number of identified metabolites were evaluated.