Evaluation of liquid-liquid extraction and liquid-solid extraction with a new sorbent for the determination of polycyclic aromatic hydrocarbons in raw and finished drinking waters

A comparative study has been made of the application of the liquid-solid extraction (LSE) technique using a new sorbent solid, tC18, and liquid-liquid extraction (EPA Method 610) of 11 polycyclic aromatic hydrocarbons (PAHs) considered by the EPA as priority pollutants. The experimental conditions of both extraction techniques are evaluated and applied to the determination of 11 PAHs using a simple HPL chromatograph with fluorometric detection. The recovery yields obtained were greater in LLE. However, for most of the PAHs the yields were found to be greater than 80% with LSE. The detection limits do not differ significantly between either technique and vary between 0.007 mu g . L(-1) (benzo[k]fluoranthene) and 1.3 mu g . L(-1) (naphthalene). The absolute standard deviations and variation coefficients of both techniques are slightly higher with LSE and vary between 0.007 and 0.37 mu g L(-1) and between 8 and 19%, respectively. The method was applied to analyze raw and finished drinking waters from four towns supplied with different water sources and qualities.