A novel approach for the quantitation of the hydrocarbon groups in heavy petroleum fractions by HPLC-RI analysis

A novel approach is presented for the accurate quantitative determination of the main hydrocarbon groups (saturates and aromatics) in heavy petroleum fractions using high-pressure liquid chromatography and refractive index detection (HPLC-RI). The concentration of each component group is determined from the RI peak areas, which are corrected using an experimentally derived function of the response factors with respect to the elution time. The calibration function is determined by analyzing a series of successively eluting subfractions, obtained by open column chromatography. The method was applied for the determination of the saturates and of the aromatic content of 16 heavy petroleum fractions, exhibiting significant differences in their compositions, and the results obtained were found to agree within 1.5 wt % with the values measured by the ASTM D2549-91 method.