A novel matrix additive, MCM-41-type mesoporous silica nanoparticles, used for analysis of peptides by MALDI-FT/ICRMS

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was thought to be unsuitable for the analysis of low-molecular-weight species since matrix peak noise made it difficult to identify analyte ions. In this study, MCM-41-type mesoporous silica nanoparticles (MSNs) were used as a matrix additive with saturated 2,5-dihydroxybenzoic acid (DHB) or α-cyano-4-hydroxycinnannic acid (CHCA) solution for the analysis of six peptides of a wide range molecular weight, Leu-Val, Phe-Val, Lue-Phe, bradykinin fragment 1-7, angiotensin II and ACTH fragment 18-39. It was shown that MSNs were capable of reducing matrix peaks with laser power lower than 34% of saturated DHB especially for low polarity analyte or CHCA especially for high polarity analyte with molecular weight less than 500 regardless of the analyte-to-matrix ratio. In addition, MSNs could suppress ionization of oligopeptide and polypeptide. The way MSN exerted its effect was supposed to be via attraction between surface silanol groups and the analyte.