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 (soxhlet, sonication, KOH-digestion, mechanical shaking, supercritical fluid extraction (SFE), accelerated solvent extraction (ASE)) and detection techniques (high resolution gas chromatography-mass spectrometry (HRGC-MS), liquid chromatography-fluorescence detection (LC-FD)) were applied to real soil samples 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 applying freeze-drying naphthalene was partly lost. SFE and ASE turned out to be as efficient as classical extraction methods Like soxhlet and mechanical shaking. Soxhlet extraction however, showed the smallest variations in the results. Recovery of PAHs after KOH-saponification were generally high as well but differences were rather high especially for the low molecular weight PAHs. Sonication proved to be a less efficient extraction technique. Due to the higher linear range of the MS compared to the fluorescence detector and practical considerations HRGC-MS was superior to LC-FD. (C) 1999 Elsevier Science B.V. All rights reserved.