Comparison of microwave-assisted extraction and Soxhlet extraction for phenols in soil samples using experimental designs

A study and comparison of microwave-assisted extraction (MAE) and Soxhlet extraction for five phenols (phenol, 2-chlorophenol, 2-methylphenol, 2-nitrophenol and 2,4-dichlorophenol) in soils was carried out in order to establish a comparative analysis between the two techniques under their optimum conditions. The optimisation of both the MAE and Soxhlet extraction methods was achieved using experimental designs. The parameters studied were pressure inside the extraction vessel, extraction time, percentage of microwave power, solvent volume and percentage (v/v) of acetone in an acetone-hexane mixture for MAE and extraction time and percentage (viv) of acetone in an acetone-hexane mixture for Soxhlet extraction. The simplex method was also used for obtaining the optimum conditions in some cases. The extracts were analysed by GC-MS or GC-FID.