Characterization of Heavy Oil by FT-ICR MS Coupled with Various Ionization Techniques

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has high resolution, so provides a viable method to characterize extremely complex mixtures. The molecular formulas of individual components are determined simply by accurate mass measurement. Here, recent advances in FT-ICR MS application to pe­ troleum derived heavy materials are reviewed after a brief introduction of the features and history of FT-ICR MS. Advantages and limitations of ionization techniques, such as electron ionization (EI), electrospray ionization (ESI), field desorption (FD), and liquid secondary ionization (LSI), connected to FT-ICR MS are evaluated by ap­ plication to petroleum derived materials. Our improved ionization techniques are also explained to adapt very complex petroleum derived samples, ex., to suppress fragmentation and to accelerate vaporization in EI, and to de­ tect specific compounds selectively in ESI. Characterization procedures to estimate the structural features of components can be based on heteroatom composition, carbon number and Z-value (hydrogen deficiency index, as a measure of degree of aromatic ring condensation), through spectral analysis using the Kendrick mass. Such characterization can be applied to estimate structural changes of components during hydroprocessing.