Master of Science (MS)
Joseph J. Pesek
Aqueous Normal Phase Chromatography, Hydrogen Deuterium Exchange, Metabolomics, Phytocannabinoids, Psychoactive Drug Analysis, TYPE-C Silica Hydride
Analytical chemistry; Biochemistry; Chemistry
Most HPLC columns are packed with silanol (Si-OH)-rich type-B silica that often participates in undesired electrostatic interactions with sample solutes and produces a poor analyte peak shape. These silanols are also known to facilitate the surface hydration required for HILIC mode to retain polar analytes. However, the hydrated surface composition can easily fluctuate, which results in poor reproducibility and requires a lengthy equilibration step. In this study, four novel stationary phases have been developed by using the TYPE-C™ silica material, in which up to 95% of the surface silanols have been replaced with Si-H group. One of the advantages of this material is the ability to retain polar molecules by operating in adsorption-based ANP mode, despite surface coverage by the non-polar Si-H group. Overall, TYPE-C™ materials eliminate most of the drawbacks observed in Type-B silica. The objectives of this study were three-fold: (1) to develop novel hydride-based columns by surface modification, (2) to evaluate the general chromatographic performances and analyte selectivity by HPLC and ESI-TOF-MS instrumentation, and (3) to explore new bioanalytical applications of the novel stationary phases and ANP chromatography. Here, practical applications of the columns were demonstrated across several research projects: the analysis of phytocannabinoids along with other psychoactive-substances; metabolomics characterization of the USDA grape cultivars; and ANP-coupled HDX-MS method development which may serve as a potential approach to reduce proton back-exchange during structural proteomics assay.
Watanabe, Seiichiro, "Synthesis and Evaluation of Novel Silica Hydride-based Stationary Phases for Bioanalytical Applications" (2019). Master's Theses. 5050.