Application of ultrasound-assisted liquid-solid extraction for the isolation of PAHs from organic-rich soil samples

Polycyclic aromatic hydrocarbons (PAHs) occur in soils at concentrations of ng•g-1 or less, and their levels are influenced by a number of factors, including the content of organic matter. Extraction of PAHs from soils, enriched in organic fraction, can be problematic, time-consuming and cost-intensive. The aim of this study was to modify an ultrasound-assisted solid-liquid extraction method, used for the isolation of 16 priority PAHs from forest soils collected from soil (sub)horizons with different organic matter content. The following parameters were considered: (i) the type and volume of solvent, (ii) the time of extraction and (iii) the purification of extracts by the SPE method. The final qualitative and quantitative determination of 16 PAHs was performed by the GC-MS method. The following results were obtained: recovery 71-107%, R2 = 0.993-0.999, LOD = 0.008-0.026 μg•ml-1 and LOQ = 0.024-0.078 μg•ml-1. The above method was successfully applied for the extraction of selected PAHs from organic soil samples collected from forest complexes located in south-central Poland.