Sequential extraction of polycyclic aromatic hydrocarbons using subcritical water

Abstract

A rapid sequential subcritical (superheated) water extraction method for polycyclic aromatic hydrocarbons (PAHs) in contaminated soil and sediment is presented. Decreasing the polarity of water by successive increase of the extraction temperature from 50 °C to 200 °C at the moderate pressure (10.3 MPa) enabled selective, non-exhaustive extractions to be performed. Concurrent with increasing temperatures to 150 °C there was an increase in PAH extraction efficiencies. For the majority of determinations no significant differences between extractions at 150 °C and 200 °C were observed. Varied extraction efficiencies of PAHs at the same extraction conditions reflected dissimilarities between environmental matrices investigated. Selective subcritical water extraction of PAHs was proportional to their octanol–water partition coefficients. This technique may be applicable in evaluation of risks associated with PAH contaminated sites and in assessments of their bioremediation potential.