Summarizing the effectiveness of supercritical fluid extraction of polycyclic aromatic hydrocarbons from natural matrix environmental samples

A summary of the supercritical fluid extraction (SFE) of polycyclic aromatic hydrocarbons (PAHs) from four natural matrix Standard Reference Materials (SRMs) is presented. The work involved the investigation of the effects of extraction fluid [carbon dioxide (CO2), chlorodifluoromethane (R22), and 1,1, 1,2-tetrafluoroethane (HFC134a)], fluid modifier (dichloromethane and aniline), temperature (60, 150, and 200 degrees C) and added water on the SFE recoveries of PAHs compared to certified results from Soxhlet extractions. For SRM 1649a (Urban Dust/Organics), R22 yielded excellent recoveries (>90% of certified concentrations) of all PAHs measured, while results for the same SRM using HFC134a as the fluid were typically <80% of the certified concentrations for most of the PAHs measured. For SRM 1941a and 1944, both aquatic sediments with similar physical and chemical compositions, extractions of the wet materials with dichloromethane-modified CO2 (10%, v/v) yielded quantitative recoveries of all PAHs for SRM 1944 but an obvious trend of lower recoveries for higher molecular weight PAHs (greater than or equal to 228 amu) for SRM 1941a, Results of SFEs of SRM 1650 (Diesel Particulate Matter) showed that this material is the most refractory of the SRMs investigated in this study, with recoveries of indeno[1,2,3-cd]pyrene and benzo[ghi]perylene at <20% of the Soxhlet results.