A fast extraction technique for extracting polycyclic aromatic hydrocarbons (PAHs) from lichens samples used as biomonitors of air pollution: Dynamic sonication versus other methods

A fast method for the extraction of polycyclic aromatic hydrocarbons, PAHs, in lichens used as biomonitors of air pollution is optimized and further applied to real lichen samples. The method consists of using the dynamic sonication-assisted solvent extraction. The lichen sample is introduced in a cell through which the extracting solvent pass at 0.2 mL/min. Sixteen PAHs were extracted from 0.2 g of dried lichens, Xanthoria parietina, in 10 min with a total extraction volume of 2 mL of hexane. The extracted fraction, previously concentrated to 500 μL, was analyzed by GC–MS without any clean-up step following extraction. Both spiked and non-spiked native samples were used for the evaluation. The procedure compared with the static ultrasonic and Soxhlet extraction, showed high efficiency with respect to both recoveries, time and solvent consumption and for all the 16 PAHs recoveries higher than 70% were obtained.The limit of detection of the investigated PAHs was in the range of 0.021–0.032 μg/g. The linear range of the entire method was 0.115–1.805 μg/g. for all the investigated PAHs. An application of the method was demonstrated with the extraction of lichens samples collected from an urban area. Twelve out of 16 investigated PAHs were found.