Mémoire, Partim B

Abstract

Laser desorption/ionization (LDI) mass spectrometry on porous silicon (MS) is a promising alternative to matrix-assisted laser desorption/ionization (MALDI) MS for the study of small molecules. Indeed, LDI-MS employs nanostructured porous silicon surfaces instead of organic matrices to assist the analyte desorption/ionization, which greatly limits the interference generated in the low m/z range, and thus allows the analysis of low molecular weight compounds. In addition, the use of porous silicon surface has the potential to provide other valuable advantages, such as the dual-polarity capabilities of the substrate, the compatibility with multimodal experiments and the possibility to functionalize the surface to improve the selectivity or the limit of detection of the technique. However, the use of porous silicon surfaces in real applications first requires a good understanding of the different aspects of the LDI-MS technique, including for example the impact of the nanosubstrate morphology on the desorption/ionization process harshness (analytes fragmentation). The objective of this Master’s thesis is to gain a better understanding of the desorption/ionization process occurring on porous silicon surfaces to ultimately optimize them for the LDI-MS analysis of small molecules such as metabolites or organic pollutants.