Stephan Hann

Research Focus

Research on mass spectrometry based metabolomics concerns metabolic profiling, metabolic flux analysis and non-targeted analysis of metabolites and intermediates in biological systems. Current method development is mainly focused on biotechnology (microbial cell factories), plant/soil related research (root exudates and microbial siderophores) and oceanography (dissolved organic matter, iron transport).

In elemental analysis method development for ultra-trace analysis in the aquatic environment (ground- and surface water, including sea water) is an essential research area. A major topic concerns the chemistry of iron in river and in sea water, where elemental and molecular mass spectrometry are combined to investigate the speciation and transport of iron. Further research focusses is on elemental speciation analysis in environmental, biological and biomedical research targeting the elements sulfur, phosphorus, platinum and selenium.

Currently two technological developments are in the center of research, i.e. ion mobility mass spectrometry, and isotopologue and tandem mass isotopomer analysis. Ion mobility mass spectrometry is regarded as an emerging technique. We have performed and contributed to several studies which have aimed at the theoretical investigation and practical application of this topic. The major goal is the establishment of procedures for accurate collision cross section measurement of primary and secondary metabolites and the determination of the uncertainty of measurement which is associated with this measurand. Moreover, the harmonization of reporting of data obtained by this novel technique is a central concern.

Metabolic flux analysis is considered as a promising tool for understanding intra-and extracellular reactions of metabolites and related compounds. We have developed novel GC-QTOFMS and LC-QTOFMS based strategies for accurate determination of isotopologue ratios. This has been applied in recent studies which have been published in Nature Communications, in Nature Biotechnology and in PNAS.