Comparison of different drying, extraction and detection techniques for the determination of priority polycyclic aromatic hydrocarbons in background contaminated soil samples

Different drying (thermal, freeze-drying, chemical drying), extraction (sox hlet, sonication, KOH-digestion, mechanical shaking, supercritical fluid ex traction (SFE), accelerated solvent extraction (ASE)) and detection techniq ues (high resolution gas chromatography-mass spectrometry (HRGC-MS), liquid chromatography-fluorescence detection (LC-FD)) were applied to real soil s amples and their influence studied with respect to the final concentrations of the 16 PAHs included in the US Environmental Protection Agency Priority Pollutants List. Thermal and chemical drying were equally suited whereas a pplying freeze-drying naphthalene was partly lost. SFE and ASE turned out t o be as efficient as classical extraction methods Like soxhlet and mechanic al shaking. Soxhlet extraction however, showed the smallest variations in t he results. Recovery of PAHs after KOH-saponification were generally high a s well but differences were rather high especially for the low molecular we ight PAHs. Sonication proved to be a less efficient extraction technique. D ue to the higher linear range of the MS compared to the fluorescence detect or and practical considerations HRGC-MS was superior to LC-FD. (C) 1999 Els evier Science B.V. All rights reserved.