3-Amino-4-hydroxybenzoic acid is the first matrix to be used specifically for carbohydrates. The other most commonly used matrices are α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, and sinapinic acid. Matrix and sample solutions are mixed prior to laser exposure, spotted on a solid metallic surface, and allowed to dry before submitting them to MALDI. These matrices are characterized by high absorptivity of the laser radiation and the capability of forming fine crystalline solids during sample/matrix drying. In general, the more fine-grained and homogeneous the morphology of crystals formed with the analyte/matrix mixture, the more intense the MALDI mass spectrum of the analyte. 3-Amino-4-hydroxybenzoic acid produced [M+Na]+ ions from as little as 1 pmol of dextran hydrolysate and N-linked glycans released from glycoproteins.
