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, ha s been used to investigate the dependence of accelerated solvent extra ction 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 i n terms of the three operating parameters was found when considering t he 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 ex traction temperature (40 degrees C) was found to be significant for na phthalene, chrysene, and benzo[b]fluoranthene. Using constant operatin g conditions (100 degrees C, 14 MPa and an extraction time of 5 min pl us 5 min equilibriation time), the influence of extraction solvent was evaluated. No dependence on recovery was found when polar organic sol vents, i.e., a dipole moment of >1.89, were used.