Advanced LC-MS-based methods for polar metabolite analysis in complex samples

A high percentage of intracellular metabolites have a polar or ionic character. Analysis of these polar metabolites in biological samples is an important task in metabolism research. These investigations can lead to an enhanced understanding of metabolic pathways. Within this thesis, novel analytical methods based on hydrophilic interaction liquid chromatography and ion exclusion chromatography were developed for separation of polar metabolites like cofactors, amino acids and small organic acids. Sensitive and selective detection was achieved by means of electrospray mass spectrometry. Moreover, determination of metabolite concentration in biological matrices was achieved by different quantification strategies like standard addition and stable isotope dilution analysis. For fast and gentle sample preparation of reactive and labile metabolites, an online solid phase extraction approach was integrated in the analytical method to prevent anaiyte degradation. This improved reproducibililty and throughput.