Abstract
Some results are introduced in studying characters of matrices influencing the desorption ionization processes in MALDI-MS, which have not been reported. By the use of low angle laser scattering photometer the association state of four matrices with lysozyme are measured. The results demonstrated that 3-amino-4-hydroxybenzoic acid (3A4HA) is the best one which can be calculated 224 molecules to associate with one molecule of lysozyme. The other three matrices, nicotinic acid (NA), 2, 5 dihydroxybenzoic acid (DHB) and caffeic acid (CA) are in the order of several tens of matrix molecules associated with one protein molecule. It is interesting to point out that 3-amino-4- hydroxybenzoic acid is the only one that cannot perform MALDI-MS spectrum and the reason is discussed. The results of the investigation in negative MALDI mass spectra of different matrices demonstrated that the desorption ionization processes are different with that of positive ions, and their mechanisms were proposed.
