STP1019

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

    Published: Jan 1989


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    Abstract

    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.

    Keywords:

    metal complexes, octaethylporphyrin, electron ionization, ammonia chemical ionization, mass spectrometry, stability index, doubly charged ions, monopyrrolic fragments, dipyrrolic fragments, demetalated geoporphyrins, fossil fuels


    Author Information:

    Beato, BD
    Research assistant and associate professor, University of Florida, Gainesville, FL

    Yost, RA
    Research assistant and associate professor, University of Florida, Gainesville, FL

    Quirke, JME
    Associate professor, Florida International University, Miami, FL


    Paper ID: STP18676S

    Committee/Subcommittee: D02.04

    DOI: 10.1520/STP18676S


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