DATA ANALYSIS OF COMPLEX METABOLOMES OBTAINED BY ION MOBILITY MASS SPECTROMETRY (IMMS)
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A recent bio-analytical application for ambient pressure ion mobility-mass spectrometry (IMMS) is the separation, detection, and identification of metabolites in complex biological matrices for the field of metabolomics. Metabolomics presents significant challenges in analytical measurements due to the diversity of metabolites and is described in detail in Chapters 1. This thesis concerns the evaluation and development of IMMS as applied to metabolomic strategies for monitoring dynamic metabolome shifts for discerning different physiological states and identifying changing metabolites in biological systems. The chapters in this thesis describe method development and data analysis for the following biological systems bacteria (E. coli (Chapter 2), cancer cell lines (Chapter 3), lymph fluid of fasting and fed rats (Chapter 4), human blood with a new IMMS design (Chapter 6), human plasma (Chapter 7), and anatomical isolated areas in rat brain (Chapter 5 and 8). For all of the experiments, principal component analysis (PCA) was used to view patterns in the data and to view which metabolites were changing the most from the controls to stress. The major findings from this thesis include: 1) overall drift time of negative ions are greater than positive ions indicating their collisional cross section is larger; 2) by coupling PCA with IMMS data patterns are viewed for different treatments; 3) online metabolomics databases couple well for identification of m/z by isotope and accurate m/z measurements; 4) quantitative analysis is accomplished using isotope dilution and standard addition; 5) applying mobility mass correlation lines to small metabolite molecules is possible for qualitative analysis to aid in the identification of metabolites in complex biological systems; 6) IMMS provides rapid isomer and/or isobar separation prior to the mass spectrometer allowing for less false positive results; 7) IMS prior to MS reduces chemical noise and enhances signal to noise ratios for analytes; 8) accurate isotope ratios are obtained by extracting m/z from specific drift times; and 9) IMMS has shown to be reproducible, sensitive, and at ambient pressure obtain a high resolving power. This approach illustrates the ability of IMMS as an analytical technique applied for the detection of metabolites in a variety of biological system.