Mass Spectrometry of Polycyclic Aromatic Compounds from Petroleum

The presence of polycyclic aromatic sulfur heterocycles (PASHs) in transportation fuels is being increasingly regulated because of their impact on the environment and refining processes. Methods for the analysis of PASHs are constantly being improved to meet the new environmental regulations requiring a reduction in the amount of sulfur. However, the successful analysis of PASHs is hindered by complex matrices, many similar compounds and low level concentrations. This dissertation is an investigation of atmospheric pressure chemical ionization (APCI) and tandem mass spectrometry (MS/MS) for improving the detection of PASHs. Limits of detection and calibration curves of model polycyclic aromatic compounds (PACs) from petroleum were determined under various conditions. Conclusions regarding ionization mechanisms, solvation effects and interferences between analytes are also presented, and thermodynamic data were calculated to support the proposed ionization mechanisms. Although model PACs from petroleum were used in this study, the results reported here are in general applicable to the analysis of non- and semi-polar compounds by APCI-MS.