Novel approach to microwave-assisted extraction and micro-solid-phase extraction from soil using graphite fibers as sorbent

A single-step extraction–cleanup procedure involving microwave-assisted extraction (MAE) and micro-solid-phase extraction (μ-SPE) has been developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) from soil samples. μ-SPE is a relatively new extraction procedure that makes use of a sorbent enclosed within a sealed polypropylene membrane envelope. In the present work, for the first time, graphite fiber was used as a sorbent material for extraction. MAE–μ-SPE was used to cleanup sediment samples and to extract and preconcentrate five PAHs in sediment samples prepared as slurries with addition of water. The best extraction conditions comprised of microwave heating at 50 °C for a duration of 20 min, and an elution (desorption) time of 5 min using acetonitrile with sonication. Using gas chromatography (GC)–flame ionization detection (FID), the limits of detection (LODs) of the PAHs ranged between 2.2 and 3.6 ng/g. With GC–mass spectrometry (MS), LODs were between 0.0017 and 0.0057 ng/g. The linear ranges were between 0.1 and 50 or 100 μg/g for GC–FID analysis, and 1 and 500 or 1000 ng/g for GC–MS analysis. Granular activated carbon was also used for the μ-SPE device but was found to be not as efficient in the PAH extraction. The MAE–μ-SPE method was successfully used for the extraction of PAHs in river and marine sediments, demonstrating its applicability to real environmental solid matrixes.