Matrix‐assisted laser desorption of peptides and proteins on a quadrupole ion trap mass spectrometer

Abstract

The use of ultraviolet matrix‐assisted laser desorption (MALD) to ionize peptides for analysis in a quadrupole ion trap is described. An ion source was modified to accommodate a fiber optic to transmit laser radiation from a notrogen laser (337 nm) to the tip of the sample probe containing peptide of protein samples in a matrix of 2,5‐dihydroxybenzoic acid (DHB) or 3,4‐dimethoxy‐4‐hydrexy‐cinnamic acid. Detection limits are demonstrated with 10 fmol of sperm‐whale‐myoglobin. The dimer of sperm‐whale myoglobin was also observed at m/z 34, 430. A. comparison is made of the tandem mass spectrum of (MS/MS) of human angiotensin I desorbed by MALD to that of the peptide desorbed by liquid secondary‐ion mass spectrometry. Both spectra were found to contain abundant structural information.