An experimental design approach for the determination of polycyclic aromatic hydrocarbons from highly contaminated soil using accelerated solvent extraction

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 nas extraction temperature. Low extraction temperature (40 degrees C) was found to be significant for naphthalene, chrysene, and benzo[b]fluoranthene. Using constant operating conditions (100 degrees 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.