LASER DESORPTION STUDIES OF HIGH MASS BIOMOLECULES IN FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY

Matrix-assisted laser desorption ionization is used to obtain Fourier-transform ion cyclotron resonance mass spectra of model peptides (e.g., gramicidin S, angiotensin I, renin substrate, melittin, and bovine insulin). Matrix-assisted laser desorption ionization yields ions having appreciable kinetic energies. Two methods for trapping the high kinetic energy ions are described: (i) the ion signal for [M + H]+ ions is shown to increase with increasing trapping voltages, and (ii) collisional relaxation is used for the detection of [M + H]+ ions of bovine insulin.