Fueling advances in ultra performance liquid chromatography – and ion mobility – mass spectrometry as platforms for x-omic analyses.
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Munisamy, Sharon Michelle.
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Analysis of x-omics samples presents a significant challenge to analytical chemists. The complexity and diversity of x-omics samples make it difficult to determine or develop the right analytical approach. This dissertation presents novel applications of ultra performance liquid chromatography – high-resolution mass spectrometry (UPLC-HRMS) and ion mobility – high-resolution mass spectrometry (IM-HRMS) in two emerging x-omics areas: lignocellulomics and petroleomics. Compared to traditional methods of x-omics analyses, these techniques offer higher chromatographic efficiency with UPLC, which can equate to faster analysis times and greater separation, an additional degree of separation with ion mobility spectrometry (IMS), and high peak resolution and mass accuracy with HRMS, which allow for identification of known and unknown analytes. Direct infusion electrospray ionization – ion mobility – high-resolution mass spectrometry (DIESI-IM-HRMS) has been evaluated as a rapid technique for the determination of total molecular composition in “whole-sample” biomass hydrolysates and extracts. IM-HRMS data reveal a high molecular weight range of biomass components (up to 1100 m/z) and provide trendline isolation of feedstock components from those introduced “in process”. Carbohydrates and other lignocellulosic degradation products were identified via HRMS exact mass measurements (with typical mass errors less than 5 ppm). Analyte assignments were supported via IM-MS collision-cross-section (CCS) measurements and trendline analysis. An automated “omics” approach utilizing UPLC-HR-TOF-MS was developed for the identification of previously unknown lignocellulosic degradation products. The approach combines traditional HRMS techniques with a “metabolomics” method for novel compound identification. Evaluation of the method for a small subset (16) of the identified peaks enabled unambiguous molecular formula assignment for 69% of the peaks. Ion mobility – mass spectrometry and several model compounds were employed to better understand asphaltene molecules in terms of their structural types and degree of structural diversity. CCS analysis demonstrates that both monomeric and dimeric archipelago- and island-type structures might be present in asphaltenes. Comparison of arrival time peak widths for asphaltenes and model compounds indicates structural or conformational diversity for asphaltene compounds within a given nominal m/z.