Abstract: The matrix-assisted laser desorption/ionization-time of flight-mass spectrometric behavior of a series of cationic porphyrins was studied. The results showed the desorption/ionization ways of cationic porphyrins were different from those of non-ionic porphyrins. The space volume of the side chain groups of the porphyrins apparently affects the desorption/ionization mechanism of the formation of ions. The larger the space volume of the side chain groups and anions is, the larger the portion of the covalence is between the porphyrin cycle cation and the balance anions. As a result, the higher mass ion peaks formed by the porphyrin cycle cation combined with more anions appeared in the MALDI-TOF mass spectra. The desorption/ionization mechanisms of the cationic porphyrins were also discussed in this paper.

Key words: Cationic porphyrins, Matrix-assisted laser desorption/ionization-time of flight-mass spectrometry, Desorption/ionization mechanisms