Analytik von Oxylipinen bei unterschiedlichen Ionisationsmethoden und fundamentale Analyse der Fragmentierungsprozesse in der Laser-Ionisation bei Atmosphärendruck

Abstract

Eicosanoids and other oxylipins play important roles in mediating inflammation and other biological processes. In order to investigate their biological roles, comprehensive analysis methods are required, with which these compounds can be reliably identified and quantified in biological matrices. Very different concentrations and different biological matrices pose enormous challenges for the modern analysis of oxylipins. In the first part of this work, a combination of solid phase extraction, charge switch derivatization, liquid chromatography, ion mobility, mass spectrometry, and bioinformatics was used to developing a novel strategy for the analysis of oxylipins. After developing and characterizing the method, it was applied to the biological matrices of cells, serum, and plasma. The results were compared with current methods of analytics of oxylipins. Subsequently, further derivatization reagents were developed in order to expand the possible analysis spectrum via stable isotope labeled derivatives, derivatives for specific functional groups, or derivatives for other ionization methods such as laser ionization at atmospheric pressure (APLI). In the second part of the thesis the APLI and the fundamental mechanisms of fragmentation during the ionization process were dealt with. In contrast to laser ionization at low pressure (multi photon ionization, MPI), APLI leads to very little fragmentation of the analytes. Both the quenching of highly excited states and the collision-induced loss of charge of the fragment ions by charge transfer were hypothesized as possible causes. These hypotheses have not been elucidated in the past to the extent that unequivocal conclusions were drawn. Through experiments and calculations with both APLI and MPI, this process was examined in more detail and basic knowledge was provided to clarify the fragmentation pathways.