Analysis of Heavy Oils by Thin-Layer Chromatography with Flame Ionization Detection†

Several rapid methods for compositional analysis of heavy oils by thin layer chromatography with flame ionization detection (FID-TLC) were investigated. Separating into four fractions, Saturates, Aromatics, Resins, and Asphalten, SARA analysis of heavy oils could be accurately performed by three stage development using n-hexane, toluene, and tetrahydrofuran. Detailed hydrocarbon type analysis of Maltene (Ma) in heavy oils could be performed adequately by using chemically bonded silica gel thin layer rods, which possess an aminopropyl or a cyanopropyl functional group, as the stationary phase. Saturates (Sa), Monoaromatics (M-Ar), Diaromatics (D-Ar), Triaromatics (T-Ar), Polyaromatics (P-Ar), and Polar compounds (Po) could be accurately determined. The standard deviation and the coefficient of variation in repeated measurements by FID-TLC method were as low as 1.5wt% or less and 10% or less, respectively. A silica gel thin layer rod coated partially with silver nitrate was prepared; and Sa, Olefins (Ol), and Aromatics (Ar) in heavy distillates could be accurately determined by using the rod as the stationary phase. The coefficient of variation in repeated measurements by this method was as low as 8% or less.