SYMPOSIA PAPER Published: 01 January 1989

The Effect of Metal Atoms on Electron Ionization and Ammonia Chemical Ionization Mass Spectra of Metalloporphyrins: Implications for Geoporphyrin Analysis


Eight metal complexes of octaethylporphyrin were analyzed by electron ionization (EI) and ammonia chemical ionization (NH3 CI) mass spectrometry. In both modes, features of the mass spectra of the metal complexes correlated well with the stability index of the metalloporphyrin, Si = [100(PE) (V)]/R, where PE is the Pauling Electronegativity of the metal, V is the valence of the metal, and R is the ionic radius of the metal. Metalloporphyrins with high stability indices produced abundant doubly charged fragments in the EI mode, and gave very little fragmentation with NH3 CI. Metalloporphyrins with low stability indices gave less intense doubly charged ions in EI, but gave abundant monopyrrolic fragments, and some dipyrrolic fragments under NH3 CI conditions. These results will be very valuable in geoporphyrin analysis, since it will now be possible to control the degree of fragmentation by inserting an appropriate metal into demetalated geoporphyrins.

Author Information

Beato, BD
University of Florida, Gainesville, FL
Yost, RA
University of Florida, Gainesville, FL
Quirke, JME
Florida International University, Miami, FL
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Developed by Committee: D02
Pages: 84–93
DOI: 10.1520/STP18676S
ISBN-EB: 978-0-8031-5080-5
ISBN-13: 978-0-8031-1198-1