UV-MALDI- Mass spectrometry: Photochemistry and Photophysics of the most commonly used matrices

I. TARZI, OLGA; ERRA BALSELLS, ROSA

Venecia

Congreso; Sixth Post-Graduate Summer School on Green Chemistry; 2003

INCA

           In order to achieve a better understanding of the photosensitized process of desorption/volatilization in UV-MALDI-MS and, given that there are no such studies in literature, we decided to start a photochemical study of several matrices in use at present. We know from previous UV-MALDI-MS experiments that certain nitrogenated sugars decompose when using 2,5-dihydroxybenzoic acid  (gentisic acid, GA) as a matrix. This decomposition is not observed when using a carboline, for example nor-harmane, as a UV-MALDI matrix. In order to find whether such decomposition occurs: (a) during the sample preparation, (b) when irradiating the matrix in the analyte presence, or (c) when the desorption of the solid is produced, we began studying the thermal and photochemical stability of  2,5-dihydroxybenzoic acid in solution. In order to conduct a comparative study, we decided to also study the thermal stability, photochemistry and photophysics of the most used compounds as UV-MALDI matrices such as: 2,4,6-trihydroxyacetophenone (THA), 4-hydroxy-a-cyano-cinnamic acid (CHC), 3,5-dimethoxy-4-hydroxy-cinnamic acid (SA) and the new matrices recently introduced by us, nor-harmane (nHo), harmane (Ho) and harmine (Ha).