Automated High-Performance Liquid Chromatography for SARA Analysis (SARA-HPLC)

SARA analysis is widely used to separate crude oil components to saturate, aromatic, resin, and asphaltene fractions. Despite the continuous improvement of the current methods, they are still suffering from insufficiencies in providing fast, accurate, and repeatable results. In this study, an automated SARA high-performance liquid chromatograph (SARA-HPLC) is developed and evaluated to overcome the aforementioned limitations and enhance SARA analysis. The developed system is equipped with three columns packed with different stationary phases, including poly­(tetrafluoroethylene) (PTFE), silica, and cyano, connected by automated six-port switching valves that can control the flow path of solvents. The system utilizes propane to sweep the primary carrier phase toward a flat and smooth baseline. A sample of 50 μL (bitumen dissolved in toluene) is passed through the columns where chromatographic separation of maltenes occurs. The asphaltene fraction precipitates on PTFE due to excess pentane, resins are adsorbed by the cyano column, and aromatics are retained on the activated silica column. After sweeping the primary carrier phase (n-pentane) using propane, the fractions are eluted from their columns by applying toluene and consequently sent to an ultraviolet light (UV) detector for analysis. The system can be run unattended and automatically, and each run needs 3 h, including system preparation. The obtained results verify that the developed analytical approach is fast, cost-effective, repeatable, and more precise than current SARA analysis methods.