AbstractsChemistry

Matrix-assisted laser desorption/ionisation (MALDI) has rapidly been established as a suitable technique for lipid analysis. In MALDI lipids form a range of adducts (protonated ([M+H] \(^+\)) and cationic ([M+Na] \(^+\), [M+K] \(^+\))), leading to spectral complexity. Promotion of a single adduct type is therefore desirable. This thesis describes optimised sample preparation strategies for MALDI-MS and imaging of lipids in biological samples. Inclusion of salt additives in MALDI matrix solutions for analysis of biological samples is considered. Nitrate salt additives are found to increase sensitivity of a given adduct type in extract samples. Similar preparations deposited via airspray for imaging are shown to have limited use owing to blockage of the spray nozzle. Incorporation of lithium into tissue samples via formal fixation is demonstrated, enabling in situ structural characterisation of highly abundant lithium-lipid adducts in MALDI-MS and imaging. Analysis of formal fixed tissues is also shown to be compatible with a relatively new surface sampling technique: liquid-extraction surface-an) complexes, was used to allow electron-transfer dissocation (ETD) of [Mg+L\(_2\)]\(^2\)\(^+\) and [Ca+L\(_2\)]\(^2\)\(^+\)), giving rise to highly abundant fatty acid side-chain informative product ions.