Markus Thoma
My contribution to the chemical characterization of environmental samples (especially PM2.5) is the development and optimization of the extraction procedure, the measurement with a high performance liquid chromatography (UHPLC) coupled to a high resolution tandem mass spectrometer (HRMS2) and the elaboration of a non-target workflow for identification of secondary organic aerosols (SOA). These steps are necessary to examine filters from ambient air and chamber experiments to understand potential sources, trends (e. g. day/night chemistry) and formation pathways. Therefor we use molecular fingerprints instead of studying every single compound in a sample. For the creation of these molecular fingerprints we use statistical methods like the hierarchical cluster analysis.