Focused microwave-assisted extraction of polycyclic aromatic hydrocarbons and alkanes from sediments and source rocks

Focused microwave-assisted extraction (FMW) of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes from sediments and rocks was compared to conventional extraction methods such as Soxhlet extraction. With the FMW technique, extraction time is reduced to 10 min and the solvent volume is small ( 30 ml). The extraction procedure and analysis was validated on a certified marine sediment standard reference material, then applied to four source rocks of different origins, compositions and analyte concentrations. Recoveries of individual compounds were calculated for both FMW and Soxhlet methods and the results suggested that there was no analyte selectivity. The moisture content of the sample matrix had a positive effect on the extraction recovery of some PAHs with a maximum increase of 30%, whereas n-alkane extraction seems less affected by this factor. The conventional biomarker parameters determined after FMW extraction were the same as those found after Soxhlet extraction. A study of matrix effects on the extraction recovery showed that the recovery of analytes was near 100% if the matrix was ground and above 74%, if the matrix was used without prior grinding