Microwave-Assisted Ionic Liquid Extraction of n-Alkanes and Isoprenoid Hydrocarbons from Petroleum Source Rock

Microwave-assisted ionic liquid extraction (MAILE) has been investigated for the extraction of n-alkanes and isoprenoid hydrocarbons from petroleum source rock and the conditions for maximum yield of the analytes were determined. An aqueous solution of an ionic liquid, 1-butyl-3-methylimidazolium bromide (BmimBr), was employed as the extracting medium. The results showed that the concentration of ionic liquid, extraction time and extraction temperatures have effects on extraction yields of aliphatic hydrocarbons with optimal conditions at: 3.0 mol L−1 ionic liquid solution, 30 min and 120 °C, respectively. The extraction yields of all the n-alkanes and acyclic isoprenoid hydrocarbons were much higher using microwave-assisted ionic liquid extraction than with Soxhlet extraction and accelerated solvent extraction. There were good correlations of the diagnostic geochemical ratios calculated from the gas chromatographic (GC) data of MAILE, Soxhlet extraction and accelerated solvent extraction. The results of this study show that MAILE is an efficient and green analytical preparatory technique for geochemical evaluation of petroleum source rock.