Greener extraction of polycyclic aromatic hydrocarbons from soil and sediment using eucalyptus oil

Polycyclic aromatic hydrocarbons are toxic pollutants which persist in the environment. Extraction of polycyclic aromatic hydrocarbons requires large volumes of toxic organic solvents, but the use of non-hazardous solvents provides a potentially cleaner approach to quantifying polycyclic aromatic hydrocarbons in environmental matrices. Here we investigated the efficiency of eucalyptus oil to extract polycyclic aromatic hydrocarbons from spiked soil and sediment. Eucalyptus oil extraction conditions including temperature, time, and volume of oil were optimized employing a Box–Behnken experimental design, and the desorption kinetics of phenanthrene, pyrene, chrysene, and benzo[a]pyrene were evaluated using an empirical first order kinetic model. Results show that extraction efficiency from soil, of 112% for phenanthrene, 108% for pyrene, 102% for chrysene and 98% for benzo[a]pyrene, is higher than that from sediment, of 90, 111, 84 and 82%, respectively. This may be due to soil possessing 12 times more organic carbon. Recoveries higher than 77% were obtained over the concentration range 0.5–10 mg/kg for the tested polycyclic aromatic hydrocarbons, with limits of detection lower than 63 µg/kg and limits of quantitation lower than 125 µg/kg. These findings suggest that eucalyptus oil has potential as a safer solvent to extract hydrophobic contaminants.