Photophysical properties of a potential MALDI matrix: 3-hydroxy-4-nitro benzoic acid

SILVA RODRIGUEZ OSCAR E.; PETROSELLI, GABRIELA; ERRA BALSELLS ROSA

CABA

Simposio; Exploring the Frontiers of Chemistry: Challenges for the 21st Century; 2019

FCEN-UBA y BEN-GURION UNIVERSITY

Sample preparation for ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI) mass spectrometry is based on dispersing an analyte in a large excess of a matrix (photosensitizer), both in solid state. The solid mixture is irradiated with a laser pulse and vaporized (ablated). Analyte gas ions are formed and then detected by mass spectrometry (MS). The mechanism of ionization during MALDI is still poorly understood and no adequate quantitative model for the complete process exists. The UV-MALDI technique involves both laser ablation and ionization of the matrix/analyte mixture after electronic excitation of the matrix. The knowledge of photophysical properties of UV-MALDI matrices should play a key role in understanding why some matrices lead more abundant post-source decay (decomposition) as well as in source decay of the analyte. Furthermore, it will be helpful in order to choose the proper matrix to optimize UV-MALDI-MS analysis. Recently, 3-hydroxy-4-nitro benzoic acid was proposed as potential MALDI matrix for polypeptide analysis.1 However, photostability studies of this compound have not been reported in bibliography. In this work, absorption and emission spectra of this compound were studied, as well as the solvent effect and the effect of the presence of an amine (e.g., ethanolamine, triethylamine, butylamine) in the medium. Photostability of the compound in solution, under 366 nm light source, has been studied too.