Determination of hydrocarbons in old creosote contaminated soil using headspace solid phase microextraction and GC–MS

Headspace solid phase microextraction (HS–SPME) has been used together with GC–MS to analyze organic substances directly in a soil, heavily contaminated with PAHs/creosote (not, vert, similar300 mg/kg soil), from an old gaswork site in Stockholm, Sweden. The HS–SPME results, both qualitative and quantitative, were compared with traditional liquid extraction using ethyl acetate/hexane (20:80). It was shown that the concentrations determined with HS–SPME at 60°C correlated well, for compounds containing up to two and three aromatic rings (naphthalenes, acenaphthene, acenaphthylene and fluorenes, while a lower concentration was obtained for phenanthrene, anthracene, fluoranthene and pyrene. The total concentrations for each compound determined with HS–SPME ranged from 2 to 25 μg/g soil. Quantification was done using standard addition of compounds directly to the soil samples. The bioavailable fraction of the compounds in the contaminated soil at 20°C was analyzed using external calibration by spiking sterile uncontaminated sand (same texture and particle size as the contaminated soil but without a heavily sorbed organic fraction) with hydrocarbon standards in different concentrations. Storage of exposed fibers at 20°C showed that analysis should be done within two days to make qualitative measurements and earlier (as soon as possible) for quantitative determinations.