Evaluation of on-line methodology for microwave-assisted extraction of polycyclic aromatic hydrocarbons (PAHs) from sediment samples

The development of novel on-line microwave techniques is described for the selective extraction of polycyclic aromatic hydrocarbons from sediment samples. Two flow systems were evaluated, in the first, samples of sediment were slurried in water and on passing through the microwave the analytes were extracted and subsequently trapped onto a C18 cartridge. Elution from the in-line C18 cartridge directly onto an analytical HPLC column was then performed. In the second study, samples were slurried in acetone and passed through the microwave cavity. The effluent was then shaken with 10 ml of hexane in order to pre-concentrate the extracted components, which were detected and quantified by GC-MS. Recoveries from the second technique on average ranged from 62 to 93% (0.28-8.15 µg). Both techniques were compared to the standard EPA method for microwave-assisted solvent extraction. The second method based on acetone, was found to give comparable recoveries to the EPA method, but offered significant improvement in the precision for replicate samples which were found to be in the range 2-7% RSD compared to 6-16% RSD for the batch technique.