Dynamic extraction in rotating coiled columns, a new approach to direct recovery of polycyclic aromatic hydrocarbons...

A new approach to the direct recovery of polycyclic aromatic hydrocarbons (PAHs) from environmental solid samples has been proposed. It has been shown that rotating coiled columns (RCCs) earlier used mainly in countercurrent chromatography can be successfully applied to the fast continuous-flow extraction of PAHs from soils. A particulate solid sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while a mixture of organic solvents (acetone-cyclohexane, 1:1, v/v) was continuously pumped through. The separation procedure requires less than half an hour, complete automation being possible. No clean-up step is needed before the subsequent HPLC- analysis of extracts. Besides, the dynamic multistage extraction performed in the rotating column at room temperature and normal pressure may have nearly the same efficiency as accelerated batch solvent extraction repeated three times at 150 degrees C and 14 MPa. Contents of PAHs in extracts obtained by using both methods are in good agreement with the certified data on the PAHs concentrations in the soil samples. The use of appropriate "mild" solvents for the dynamic extraction in rotating columns may be very perspective for the simulation of naturally occurring processes and determination of environmentally-relevant forms of PAHs and other pollutants in environmental solids. A particular emphasis could be placed on time-resolved (kinetic) studies of the mobilization of toxicants in soil systems.