Compound characterization in complex mixtures has applications in diverse areas such as the pharmaceutical, health, and petroleum industries. Measurement problems arising from complex mixtures include the overwhelming of the analytical peak capacity, the wide concentration range of the different analytes, and the inter-sample concentration variability of given molecular species. Therefore advances in the rapid identification of compounds such as improvements in peak capacity and analyte selectivity are an active area of scientific research. This dissertation presents research that is directed at improving these measurement areas. For petroleum samples, silver cationization coupled with ion mobility spectrometry... More
Compound characterization in complex mixtures has applications in diverse areas such as the pharmaceutical, health, and petroleum industries. Measurement problems arising from complex mixtures include the overwhelming of the analytical peak capacity, the wide concentration range of the different analytes, and the inter-sample concentration variability of given molecular species. Therefore advances in the rapid identification of compounds such as improvements in peak capacity and analyte selectivity are an active area of scientific research. This dissertation presents research that is directed at improving these measurement areas. For petroleum samples, silver cationization coupled with ion mobility spectrometry---tandem mass spectrometry (IMSMS/ MS) is presented as a means to improve compound selectivity (sulfur-containing molecules) and species identification. The approach showed that silver-sulfur ions demonstrate higher mobilities compared with protonated nitrogen-containing compounds. Furthermore, at lower m/z values, mostly elongated structures (with lower DBE values) were favored. Conversely, more compact structures (with higher DBE values) were favored at higher m/z values. Additionally, cyclic structures were favored over acyclic structures and S1, S2, and S3 molecular classes were favored over other molecular classes in sulfur-containing petroleum compounds. In separate studies, hydrogen/deuterium exchange (HDX), hydrogen deuterium scrambling (HD scrambling), and collision-induced dissociation (CID) were coupled with IMS-MS measurements to assist in the characterization of metabolites, lipids, and peptides. Unique mass spectral patterns were obtained for different classes of biological molecules upon HDX. The use of these HDX patterns in combination with CID and collision cross section (CCS) data were demonstrated as an aid for the identification efforts for dataset features from a bovine heart extract sample. Lastly, HDX kinetics modeling was used to estimate the relative abundances of sucrose conformers contributing to experimental HDX profiles. These advances in compound identification have implications for the health and energy industries. An example for the former is the discovery of important biomarkers associated with disease progression. For the latter, such characterizations may help to optimize the refining process for different petroleum samples. Future trends to improve these new measurements are presented and discussed.
