USE OF 2-HYDROXY-1-NAPHTHOIC ACID AS A MATRIX FOR MATRIX-ASSISTED LASER-DESORPTION IONIZATION MASS-SPECTROMETRY OF LOW-MOLECULAR-WEIGHT PORPHYRINS AND PEPTIDES

Use of the matrix-assisted laser desorption/ionization matrix 2-hydrox y-1-naphthoic acid provides a 2-4-fold enhancement of ion signal for l ow molecular mass porphyrins over other matrices including alpha-cyano -4-hydroxycinnamic acid, 2-(4-hydroxyphenylazo)benzoic acid, sinapinic acid and 2,5-dihydroxybenzoic acid. Tetraphenyl-, octaethyl-and tetra methoxyphenylporphyrins give strong signals corresponding to [M + H]() ions and limits of detection between 100 and 500 fmol. Significant f ragmentation is observed for the octaethylporphyrins at high laser pow er and moderate fragmentation is observed for the other classes of por phyrins. The 2-hydroxy-1-naphthoic acid matrix also gives strong signa ls corresponding to [M + H](+) and/or [M + Na](+) ions for peptides, i ncluding methionine enkephalin, bacitracin, bradykinin, renin substrat e and insulin.