New capabilities and applications of ambient ionization mass spectrometry for the surface analysis and imaging of lipids

Mass spectrometry is arguably the most important technique used in lipid analysis. It provides unparalleled sensitivity and molecular specificity in the detection, quantification and structure elucidation of the diverse range of lipids present in complex biological matrices. The recent and rapid emergence of ambient ionization mass spectrometry presents new and exciting opportunities for the direct detection of lipids from surfaces, including those commonly encountered in lipid research such as tissue sections, cells and thin-layer chromatography plates. This thesis describes the application, optimization and analytical capabilities for two contemporary ambient ionization technologies - namely desorption electrospray ionization (DESI) and liquid extraction surface analysis (LESA) - for the surface and structural analysis of lipids from all three of these sample/substrate classes. Herein the results of ambient ionization analysis are shown to: (i) provide new insight into the distribution (and thus function) of individual lipids within human lens tissue; (ii) monitor and exploit surface chemistry such as the oxidation of unsaturated lipids by atmospheric ozone; and (iii) obtain lipid profiles allowing for the identification of cell types, including analysis of single cells, by coupling LESA-MS with inkjet bio-printing technologies. Results from this thesis serve to highlight the great potential of ambient surface analysis mass spectrometry for lipid research