Composition of Sulfur-Containing Components of Crude Oils from the Volga–Ural Petroleum and Gas Province: a Study by Various Mass Spectrometric Methods

The composition of sulfur-containing compounds present in a representative set of crude oils from the Volga–Ural petroleum and gas province was studied by two-dimensional gas chromatography with mass-spectrometric detection and by ultra-high-resolution mass spectrometry with electrospray ionization and atmospheric pressure photoionization. The sulfur-containing aromatic compounds have a large set of isomers differing in the positions of alkyl substituents. A correlation analysis of the intensity distribution of sulfur-containing ion peaks in the mass spectra recorded with atmospheric pressure photoionization suggests different formation pathways of different classes of sulfur-containing compounds. These compounds can be subdivided into four groups within each of which the initial compounds and formation mechanisms are similar.