Optimisation and comparison of microwave-assisted extraction and Soxhlet extraction for the determination of polychlorinated biphenyls in soil samples using an experimental design approach

Optimisation of microwave-assisted extraction (MAE) for the extraction of polychlorinated biphenyls (PCBs) from soil samples has been accomplished using an experimental design approach. Variables studied have been: percentage of acetone (v/v) in an acetone:n-hexane mixture, solvent volume, extraction time, microwave power and pressure inside the extraction vessel. Five samples of a certified soil (CRM 481) have been extracted under the optimum conditions of the developed method and the results have been compared to those obtained by Soxhlet extraction. Good recoveries (>95%) have been obtained for all the PCBs studied. All extracts have been analysed by gas chromatography/mass spectrometry (GC/MS) and an optimum determination method for the electron impact mass spectrometric (EIMS) has also been developed.