Chiral Recognition by Means of Mass Spectrometry

Sammanfattning: This thesis is based on experimental studies of chiral ions in the gas-phase. An electrospray ion source platform (Stockholm University) and a commercially available quadrupole time-of-flight mass spectrometer (University of Oslo) have been used in our studies. Using the advantages of tandem mass spectrometry, we have investigated interactions between protonated amino acids, namely phenylalanine (Phe), tryptophan (Trp), and methionine (Met), and Trp containing diastereomeric complexes with chiral (2-butanol) and achiral (argon) targets. In high energy collisions of 1 keV in the center-of-mass (c.o.m.) frame, collision induced dissociation (CID) via multiple channels independent on the chirality of either the projectile or the target was observed. The fragmentation via loss of H2O + CO and NH3 were found to be the main reaction channels for all of the studied amino acids. The energy gained in the collision was found to be sufficient to initiate fragmentation via various competitive reaction pathways. Chiral recognition in CID of the diastereomeric proton-bound complexes of tryptophan and 2-butanol as a function of collision energy with argon was studied. Stereo dependent dissociation of the complexes was observed, and for the first time an energy dependence has been measured for such a complex. Where possible, comparisons with previously reported results have been performed.