Matrix additive for mass spectrometry

摘要

The application is directed to MALDI matrix additives based on 5-alkoxy-2- or -3-hydroxybenzoic acid represented by the following formula (I):
where R is an alkyl group having 6 to 10 carbon atoms and the substituted carboxyl group and hydroxyl group are ortho or meta to each other. A preferred embodiment comprises 5-octyloxysalicylic acid. By including the additive in a matrix for mass spectrometry selected from the group consisting of ±-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, sinapic acid, and 1,5-diaminonaphthalene, the ionization efficiency of hydrophobic peptides is increased, leading to improved MALDI-MS analysis of hydrophobic proteins.