Distribution of Polycyclic Aromatic Sulfur Heterocycles in Three Saudi Arabian Crude Oils as Determined by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

The distribution pattern of polycyclic sulfur aromatics was established in three Saudi Arabian crude oils using a combination of liquid chromatography on a bonded Pd(II) phase and Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The highest double bond equivalent (DBE) measured was 17 for the Arabian heavy crude oil and 14 for both Arabian medium and Arabian light crudes. The high DBE number indicates the presence of a large variety of parent ring systems; knowledge of them is important in the characterization of crudes with respect to their processing properties. A higher sulfur concentration was correlated with more alkyl carbons in the aromatic compounds and with a higher DBE. A representation of the mass spectral data in a pseudogram, a form that resembles a chromatogram, is introduced to facilitate the quick visual inspection and comparison of the mass spectral data.