A Comparative Study on Extraction of Organic Matters in Source Rocks by Accelerated Solvent Extraction and Soxhlet Extraction

The application of accelerated solvent extraction (ASE) technique to the extraction of extractable organic matters in source rocks with ASE 200 are discussed by comparing with traditional Soxhlet extraction technique. Based on analytical results of a mudstone sample from northeast China, the effects of dispersion ratio, extraction temperature and pressure conditions on the determination were discussed and the extraction conditions for extracting organic matters in source rocks with accelerated solvent extraction was optimized with dispersion ratio of 8∶3; extraction temperature of 110℃; extraction pressure of 10.3 MPa and heating time of 5 min. Under the optimized experimental condition, the satisfactory result was obtained with recovery rate of higher than 90% and precision of 2.6%RSD (n=10). Additionally, the bulk chemical composition of the chloroform bitumen obtained with accelerated solvent extraction from the Dongshen 1 source rock collected from TuHa Basin of China is also very close to those obtained with soxhlet extraction. The GC-MS analytical results of the aliphatic and aromatic fractions of the extracts from other six source rocks obtained with accelerated solvent extraction and Soxhlet extraction, separately also show very good consistence. The molecular abundances, distribution patterns and geochemical parameters of normal alkanes, polycyclic terpanes, steranes, and aromatic hydrocarbons obtained with both accelerated solvent extraction and Soxhlet extraction are consistent. The results suggest that the accelerated solvent extraction technique can be applied to the extraction of organic matters in source rocks and as the pretreatment method for further organic geochemistry analysis.