Multielement molecular size fractionation in crude oil and oil residue by size exclusion microchromatography with high resolution inductively coupled plasma mass spectrometric detection (HR ICP MS)

Microchromatography using permeation through gels with the increasing exclusion limit (5000, 400 000 and 20 000 000 Da) was combined with high resolution ( R = 4000) ICP MS to measure the distribution of Co, Cr, Fe, Ni, S, Si, V and Zn as a function of the molecular mass fraction of crude oil and oil vacuum distillation residue. The accuracy of the simultaneous multielement determination was verified by the µflow-injection-ICP MS analysis of certified reference materials (wear-metals in lubricating oils: SRM 1084a and SRM 1085b). The method allowed the acquisition of chromatograms with high sensitivity competitive existing methods, showing element- and sample origin-dependent morphology. A multielement distribution pattern as a function of molecular size could be obtained in crude oils by µSEC-ICP HR MS.