Optimization of microwave-assisted extraction of hydrocarbons in marine sediments: comparison with the Soxhlet extraction method

Abstract

Microwave energy was applied to extract polycyclic aromatic hydrocarbons (PAHs) and linear aliphatic hydrocarbons (LAHs) from marine sediments. The influence of experimental conditions, such as different extracting solvents and mixtures, microwave power, irradiation time and number of samples extracted per run has been tested using real marine sediment samples; volume of the solvent, sample quantity and matrix effects were also evaluated. The yield of extracted compounds obtained by microwave irradiation was compared with that obtained using the traditional Soxhlet extraction. The best results were achieved with a mixture of acetone and hexane ¶(1 : 1), and recoveries ranged from 92 to 106%. The extraction time is dependent on the irradiation power and the number of samples extracted per run, so when the irradiation power was set to 500 W, the extraction times varied from 6 min for 1 sample to 18 min for 8 samples. Analytical determinations were carried out by high-performance liquid chromatography (HPLC) with an ultraviolet-visible photodiode-array detector for PAHs and gas chromatography (GC) using a FID detector for LAHs. To test the accuracy of the microwave-assisted extraction (MAE) technique, optimized methodology was applied to the analysis of standard reference material (SRM 1941), obtaining acceptable results.