Pressurised Liquid Extraction of Polycyclic Aromatic Hydrocarbons from Soil and Sediment Samples

Pressurised liquid extraction (PLE) is essentially an analyteand matrix-independent technique. It provides cleaner extracts than the time-consuming classical procedures. In this study, PLE was miniaturised and performed in a stainless-steel cell of 10 mm x 3 mm I.D. 50 mg amounts of the solid samples were packed in the holder. After being subjected to the PLE procedure, 50 out of 100-μl extracts were introduced into GC–MS using large-volume injection (LVI). The new device was applied to the determination of polycyclic aromatic hydrocarbons (PAHs) in soils and sediment. Evaluation of the pressure and temperature during extraction, and extraction solvent volume and nature (typical variables affecting the PLE efficiency) resulted in selection of 100 μl of toluene at 15 MPa for 10 min in a staticdynamic mode using not more than 50-mg samples. Clean-up or filtration of the extracts was not required. Detection limits for the complete at-line PLE–LVI–GC–MS procedure were below 9 ng/g soil for the thirteen most volatile EPA PAHs in real soil samples. Repeatability (expressed as RSD values) was better than 15%. Comparison of PLE with Soxhlet or liquid-partitioning extraction showed that the efficiency of PLE is the same or better for both spiked and nonspiked samples.