Relative recoveries of hydrocarbons from geological samples using high temperature supercritical fluid extraction: Contributions from thermal desorption

The extraction of n-alkanes, polyaromatic hydrocarbons (naphthalene, methyl ated naphthalenes, phenanthrene, methylated phenanthrenes, anthracene, and methylated anthracenes) and biomarkers (hopanes) from Posidonia shale by hi gh temperature supercritical fluid (HT-SFE) carbon dioxide extraction has b een evaluated, including the relative contributions from thermal desorption and relative comparisons to conventional Soxhlet extraction. These current results confirm those of previous studies indicating a widely differing ex tractability of strongly and weakly associated hydrocarbons in ancient sedi ments and the significantly higher recoveries possible using HT-SFE compare d to conventional Soxhlet extraction. The present study also demonstrates t hat these high HT-SFE recoveries are due to true extraction rather than sim ple thermal desorption and that this procedure is a useful tool to study sp eciation as well as total extractable hydrocarbons from sediments.