Dissertation/Thesis Abstract

The author has requested that access to this graduate work be delayed until 2018-08-02. After this date, this graduate work will be available on an open access basis.
Exposomics by Liquid Chromatography-ESI-Drift-Tube Ion Mobility Quadrupole Time-of-Flight Mass Spectrometry: A Proof-of-Principle Study
by Lai, Yunjia, M.S., University of California, Davis, 2017, 80; 10288191
Abstract (Summary)

Exposomics is challenging due to the low abundance, vast dynamic range, and structural diversity of exposome molecules, and is further complicated by matrix effects. The recent coupling of ion mobility spectrometry to mass spectrometry (IMS-MS) has been proposed as a promising solution for exposomics because of its increase in coverage, peak capacity, dynamic range, without compromising sensitivity and throughput compared to mass spectrometry alone. Here, we propose the first proof-of-principle study testing an actual IMS-MS instrument for exposomic analysis of complex biological matrices. In this study, a novel drift-tube ion mobility-quadrupole time-of-flight mass spectrometer (DTIMS-QTOF MS) was employed, coupled with cutting-edge phospholipid-removing solid phase extraction (SPE) and hydrophilic interaction chromatography (HILIC). An in-depth evaluation of this SPE-LC-DTIMS-QTOF workflow was conducted via a spiking trial, for which common exposome compounds were queried, collected, and spiked into human plasma at health-relevant levels. Results of this study provide strong evidence endorsing the incorporation of DTIMS into LC-QTOF for exposomics: (i) improved peak capacity without substantial compromise in duty cycle; (ii) EIC noise level isobar ions were revealed as separated by IMS drift spectrum; (iii) a linear dynamic range comparable to LC-QTOF, with some ions observed at much lower concentration levels; (iv) collision cross sections (CCS) (Single-Field calibration) was highly reproducible (0.2% RSD) and accurate (0.9% RSD), and correlated well with mass (R2 > 0.91). This work may be useful for future exposomics practitioners or IMS-MS users in biomedical and environmental arenas.

Indexing (document details)
Advisor: Fiehn, Oliver
Commitee: Ebeler, Susan E., Zhang, Qi
School: University of California, Davis
Department: Agricultural and Environmental Chemistry
School Location: United States -- California
Source: MAI 56/06M(E), Masters Abstracts International
Subjects: Environmental Health, Chemistry
Keywords: Environmental health, Exposome, Human blood plasma, Ion mobility-mass spectrometry, Metabolomics, Untargeted analysis
Publication Number: 10288191
ISBN: 9780355152036