Ultrasonication extraction and solid phase extraction clean-up for determination of US EPA 16 priority pollutant polycyclic aromatic hydrocarbons in soils by reversed-phase liquid chromatography with ultraviolet absorption detection

A method using ultrasonication extraction and solid phase extraction (SPE) clean-up for determination of US EPA 16 priority pollutant polycyclic aromatic hydrocarbons (PAHs) in soils by reversed-phase liquid chromatography (RP-LC) with ultraviolet (UV) absorption detection was studied. Separation and detection of the 16 PAHs were completed in 31 min by RP-LC with a C18 column (Bakerbond PAH 6 PLUS 125×3.0 i.d. mm or Phenomenex ENVIROSEP-PP 125×3.2 i.d. mm), acetonitrile–water gradient elution and UV absorption detection. The detection limits, for a 10 μl of solution injection, determined at 254 nm were less than 1 μg/ml, except for acenaphthene, which was 1.05 μg/ml. Because individual PAHs are present in soils at the ng/g level or below and few sample matrices can be analyzed directly without serious interference, efficient extraction, preconcentration and clean-up of PAHs from the samples are indispensable prior to the determination of the PAHs. Several organic solvents were tested for extraction of the PAHs from soils, and ultrasonication extraction was used for the extraction in acetone of the 16 PAHs in soils. Several SPE procedures were tested and compared, and Supelco 6 ml LC-18 SPE cartridge and acetone:tetrahydrofuran (THF)=1:1 eluant were used for the preconcentration and clean-up of the 16 PAHs in the soil. The method was successfully applied to determine the 16 PAHs in the soil sampled from an industrial land in the UK.