Extraction of petroleum hydrocarbons from soil by mechanical shaking

A shaking extraction method for petroleum hydrocarbons in soil was develope d and compared to Soxhlet extraction. Soxhlet extraction is an EPA-approved method for volatile and semivolatile organic contaminants from solid mater ials, hut it has many disadvantages including long extraction periods and p otential loss of volatile compounds. When field-moist soils are used, varia bility in subsamples is higher, and the extraction of hydrocarbons with a n onpolar solvent may be less efficient. A shaking method was designed to fil l the need for simpler and more efficient extraction of petroleum hydrocarb ons from soil. A systematic study of extraction conditions was performed fo r various soil types, soil weights, solvents, extraction times, and extract ion cycles. The results were compared to those for Soxhlet extraction. Shak ing 1 g of soil with a sequence of three 10-mL aliquots of dichloromethane or acetone was found to be equivalent to Soxhlet extraction for total petro leum hydrocarbons and polycyclic aromatic hydrocarbons. Shaking with aceton e was more consistent than all other methods for the extraction of specific compounds from aged, contaminated soil. The shaking method appears to be a pplicable to a wide range of soil types and petroleum contaminants but shou ld be compared to Soxhlet extraction for new conditions.