An experimental design approach, based on central composite design, has been used to investigate the dependence of accelerated solvent extraction operating variables (pressure, temperature, extraction time) on the recovery of 16 polycyclic aromatic hydrocarbons (PAHs) from native, contaminated soil. At the 95% confidence interval, no significance in terms of the three operating parameters was found when considering the total PAH recovery. However, when individual PAHs were considered, some compounds were found to be dependent on operating variables. The most significant operating variable was extraction temperature. Low extraction temperature (40 °C) was found to be significant for naphthalene, chrysene, and benzo[b]fluoranthene. Using constant operating conditions (100 °C, 14 MPa and an extraction time of 5 min plus 5 min equilibriation time), the influence of extraction solvent was evaluated. No dependence on recovery was found when polar organic solvents, i.e., a dipole moment of >1.89, were used.
Accelerated solvent extraction (ASE) is a new technique forthe extraction of a range of organic pollutants from soils and related material. 1 The technique is based on the use of a solvent or combination of solvents to extract organic pollutants at elevated pressure and temperature from a solid matrix. [2][3][4] The range of organic pollutants for which the technique is proposed includes semivolatile compounds, organochlorine pesticides, organophosphorus pesticides, chlorinated herbicides, and polychlorinated biphenyls. 1 As the semivolatile compounds includes polycyclic aromatic hydrocarbons (PAHs), it was the intention in this paper to investigate the interdependence of selected operating parameters on their recovery from a native, highly contaminated soil.Previous work in this laboratory 4 has confirmed that PAHs can be effectively extracted from soil using the proposed Environmental Protection Agency (EPA) operating conditions of pressure, 14 MPa, temperature, 100 °C, and extraction time 5 min plus a 5 min equilibriation time period using a 1 + 1 solvent mixture of acetone and dichloromethane. 1 As the main operating variables identified were pressure, temperature, and extraction time, these operating parameters were chosen to allow the robustness of the proposed EPA method to be considered. The method of optimiza-