Effect of moisture on the extraction efficiency of polycyclic aromatic hydrocarbons from soils under atmospheric pressure by focused microwave-assisted extraction

The effects of the moisture content in the original, air-dried and re-moist ened matrices as well as solvent have been studied on the recovery of polyc yclic aromatic hydrocarbons (PAHs) from soil by a focused microwave-assiste d extraction (FMAE) method. Solvents selected for the extractions were cycl ohexane-acetone (1:1), hexane-acetone (1:1) and dichloromethane. On the ext raction of 20-day aged spiked soil, the highest recovery was found by apply ing hexane-acetone mixture. Spiked soil sample, quality control sample and real soil sample were used for the evaluation of moisture effect. It indica ted that the presence of water in the soil is important for the recovery en hancement of PAHs and with this presence it is possible to avoid drying ste p with the FMAE technique. A comparison between microwave and 16-h Soxhlet methods has been made. It evidenced that the microwave-assisted extraction under ambient atmospheric pressure is a suitable alternative to Soxhlet ext raction for the analysis of PAHs in soils. (C) 2001 Elsevier Science B.V. A ll rights reserved.