Optimization of a microwave-assisted extraction method for phenol and methylphenol isomers in soil samples using a central composite design

A simple and rapid microwave-assisted extraction (MAE) procedure was developed and optimized for phenol, o-cresol, m-cresol and p-cresol in soil samples. The spiked soil used was prepared 25 d before treatment to simulate weathering processes and to allow for the formation of analyte-matrix interactions, The samples, immersed in hexane-acetone, were irradiated with microwaves in a closed-vessel system, Optimization of the method was achieved by using a factorial design approach on parameters such as the volume of solvent, the percentage of acetone and the extraction temperature. The MAE procedure yielded extracts that could be analyzed directly using a GC-flame ionization detection system without any preliminary clean-up or concentration steps.