Speciation Distribution of Polycyclic Aromatic Sulfur Heterocycles in Crude Oil

A method for speciation analysis of polycyclic aromatic sulfur heterocycles (PASHs) in crude oil was established. The PASHs were separated from the oil sample by ligand exchange chromatography using SiO2 with PdCl2. The sulfur compounds were then determined by gas chromatography using a mass spectrogram detector (GC/MS), gas chromatography with a sulfur chemiluminescence detector (GC-SCD), and chromatography retention index of the compounds. More than 100 PASHs (including alkyl benzothiophene, dibenzothiophene, and alkyl dibenzothiophene) were identified. The dibenzothiophene and alkyl dibenzothiophene represent about 91 % of the total PASHs in crude oil. The method can be applied for speciation analysis of PASHs in crude oils from different sources.