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Implementation of Liquid Chromatography, Ion Mobility Spectrometry, and Mass Spectrometry for the Analysis of Steroids and Lipids
Steroids and lipids are biologically important for cellular signaling and energy/metabolism, respectively. Steroid and lipids have many isobaric species, wide variance on biological concentration, and complicated ionization patterns. Therefore, this dissertation focuses on employing liquid chromatography (LC), ion mobility spectrometry (IMS), and mass spectrometry (MS) techniques to enhance the analysis of steroids and lipids. There are three major themes: (1) Increasing the accuracy of IMS collision cross section (CCS) calibration, (2) Enhancing separation of steroid and steroid conjugates through IMS using metal adduction, and (3) Applying these techniques to biological mixtures. The first four chapters focus on increasing the accuracy of IMS CCS calibration. Chapter 1 contains an introduction to IMS and discusses the current state of CCS calibration research. Chapter 2, Chapter 3, and Chapter 4 applies an analytical approach to understanding the best calibration function, experimental parameters, and calibrant to employ, respectively. This research will advance the accuracy of CCS calibration and is implemented for all CCS calibration performed in this dissertation. The next five chapters focus on the use of metal adduction to enhance the separation of steroids and steroid conjugates through IMS. Chapter 5 provides a background for steroid analysis through IMS. Chapter 6 and Chapter 7 examine separation of steroid isomers as group I metal adducts through IMS as one-component and multicomponent mixtures, respectively. Chapter 8 focuses on group I metal adduction for separation of estradiol glucuronide isomers through IMS coupled with tandem mass spectrometry techniques for isomer discrimination. Chapter 9 incorporates LC analysis for the same isomers analyzed in Chapter 7 to enhance separation and apply to complex mixtures. Chapter 10 and 11 focus on the analysis of steroids and lipids in biological mixtures. Chapter 10 demonstrates a novel serum microextraction technique for simultaneous analysis of corticosterone and lipids. Chapter 11 then couples the Chapter 10 with mass spectrometry imaging (MSI) to analyze lipid alterations due to maternal diet in maternal serum, placentas, and fetuses at mid-gestation. Overall, this work covers the analysis of steroids and lipids from fundamental gas-phase chemistry to enhanced sample preparation to the analysis of a reproductive model.
Rister, Alana L, "Implementation of Liquid Chromatography, Ion Mobility Spectrometry, and Mass Spectrometry for the Analysis of Steroids and Lipids" (2019). ETD collection for University of Nebraska - Lincoln. AAI27666558.