High spatial resolution chemical imaging and accelerated bimolecular reactions using ambient ionization mass spectrometry: Desorption electrospray ionization (DESI) and low temperature plasma (LTP) ionization.

摘要

The introduction of ambient ionization methods has increased the performance of analytical mass spectrometry. Ambient ionization permits the analysis of samples in their native environment with minimal to no sample preparation. The initial part of my dissertation research focused on studying the phenomena which governs the increase in reaction rates associated with bimolecular reactions in a variant of the conventional desorption electrospray ionization (DESI) method, reactive-DESI. Additionally, a methodology was developed to improve the spatial resolution (smallest feature distinguishable in a chemical image) of the technique, in another DESI experiment referred to as DESI imaging mass spectrometry, and enabled the resolution of features as small as 35 μm. High resolution imaging was demonstrated for both a conventional DESI source and a fixed geometry DESI source (FG)-DESI. My dissertation culminates with the use of low temperature plasma (LTP) ionization, a relatively new ambient ionization source for the imaging of semi-volatile fragrance compounds on various surfaces, determining high throughput capabilities and the distribution of compounds on a surface through chemical imaging. In summary, this dissertation has focused on studying the fundamental aspects and avenues for improving the applicability of various ambient ionization techniques.