Methyldibenzothiophene isomer ratio in crude oils: Gas chromatography tandem mass spectrometry analysis

The quantification of Methyldibenzothiophene isomers (MDBTs) is used in the geochemical characterization of crude oils. The relative ratio of these isomers can give useful information about the nature and the maturity of the source rock. This paper describes a novel analytical technique for the quantitative determination of MDBTs through triple quadrupole tandem mass spectrometry (GC–MS/MS). Through the multiple reaction monitoring (MRM) scan mode, it was possible to reach high selectivity for the MDBTs and their quantification was obtained without preliminary fractionation of the crude oil. In order to reduce the carryover of high boiling components, a recently developed backflush system in the GC program was applied. This novel protocol has been tested on sixteen samples of crude oil from different oil fields around the world. It was concluded to be more reliable than previously reported analytical methods based on selected ion monitoring (SIM) scan mode.

► Quantification of Methyldibenzothiophene isomers (MDBTs) is used as a marker in the geochemical characterization of crude oils.
► The quantification through previously reported analytical methods required fractionation steps.
► This paper describes a novel analytical technique for the determination of MDBTs without preliminary fractionation.
► The Backflush technology reduces strongly the carryover.