Argentation chromatography coupled to ultrahigh‐resolution mass spectrometry for the separation of a heavy crude oil

- Analysis of heavy crude oil by HPLC coupled to MS-measurements was preformed.
- More information was obtained compared to the direct MS-analysis.
- Separation is achieved by the interactions between aromatic analytes and silver(I) ions of stationary phase.
- Analytes with long chains bind weaker and have shorter retention times.

Simplification of highly complex mixtures such as crude oil by using chromatographic methods makes it possible to get more detailed information about the composition of the analyte. Separation by argentation chromatography can be achieved based on the interaction of different strength between the silver ions (Ag+) immobilized through a spacer on the silica gel surface and the π-bonds of the analytes. Heavy crude oils contain compounds with a high number of heteroatoms (N, O, S) and a high degree of unsaturation thus making them the perfect analyte for argentation chromatography. The direct coupling of argentation chromatography and ultrahigh-resolution mass spectrometry allows to continuously tracking the separation of the many different compounds by retention time and allows sensitive detection on a molecular level. Direct injection of a heavy crude oil into a ultrahigh-resolution mass spectrometer showed components with DBE of up to 25, whereas analytes with DBE of up to 35 could be detected only after separation with argentation chromatography. The reduced complexity achieved by the separation helps increasing the information depth.