The occurrence and distribution of low-molecular-weight sulphoxides in polar fractions of sediment extracts and petroleum

Polar fractions of sediment extracts and a crude oil were isolated and analyzed for low-molecular-weight (LMW) sulphoxides. Sediment extracts were found to contain relatively high amounts of sulphoxides as demonstrated by X-ray absorption analyses and chemical reduction of sulphoxides followed by the isolation of the formed LMW sulphides. The amounts of cyclic sulphoxides are comparable to the amounts of cyclic sulphides present as such. The distribution of sulphides and sulphoxides were slightly different indicating preferential oxidation of specific sulphides. The sulphoxides may be formed during long-time storage of samples or during weathering of sediment outcrop samples. The results further indicate that carbon skeletons released by desulphurization of polar fractions are partially (up to 60%) derived from LMW sulphoxides.