Studies on the selection of new matrices for ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A new group of compounds has been successfully tested as matrices for ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI MS). Several new matrices for UV-MALDI MS have been found by choosing, as potential matrices, compounds that perform an intramolecular proton transfer along an intramolecular H-bond under UV irradiation. Compounds of this type are, for example, salicylamide, salicylanilide, several ortho-hydroxyacetophenones and ortho-hydroxybenzophenones. The matrix activity of these compounds is compared to the corresponding meta- and para-isomers and to the matrix activity of such well known matrices as 2,5-dihydroxybenzoic acid and 2,4,6-trihydroxyacetophenone. It was found that meta- and para-substituted hydroxycarbonyl compounds show either a significantly lower or no matrix activity compared with the ortho isomers.