title: A fast atom bombardment and matrix-assisted laser desorption/ionization mass spectrometry study of doubly charged porphyrins.
abstract: In this mass spectrometry (MS) study of doubly charged porphyrin salts, fast atom bombardment (FAB) and matrix-assisted laser desorption/ionization (MALDI) MS techniques are utilized to examine several unique ionic species. The predominant transformation of preformed doubly charged ions in the desorption/ionization mechanism of FAB and MALDI is the result of deprotonation reactions to form singly charged ions of the type [M(2+) - H(+)](+) and of one-electron reductions to form radical cations [M(2+) + e(-)](+.). The dependence of this phenomenon and the formation of a number of additional ionic species on the different matrices and the FAB-matrix additive benzoquinone is examined. The significant analogous behavior of doubly charged porphyrins in FAB- and MALDI-MS leads to the conclusion that one-electron reductions are of distinct relevance in the desorption/ionization mechanism of MALDI.
authors.affiliation: Mass Spectrometry Facilities, Institute of Organic Chemistry, University at Cologne Greinstr. 4, D-50939 Cologne, Germany. mathias.schaefer@uni-koeln.de
authors.forename: M
authors.initials: M
authors.lastname: Schäfer
authors.forename: H
authors.initials: H
authors.lastname: Budzikiewicz
mesh_terms: D016227:Benzoquinones; D004563:Electrochemistry; D004566:Electrodes; D007202:Indicators and Reagents; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000032:analysis*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D016227:Benzoquinones; D007202:Indicators and Reagents; D011166:Porphyrins