title: Selective supercritical fluid extraction to estimate the fraction of PCB that is bioavailable to a benthic organism in a naturally contaminated sediment.
abstract: Selective supercritical fluid extraction (SFE) at 40 degrees C, 120 bar and 60 min was utilised as a means to estimate the bioavailable fraction of PCBs to chironomid larvae in a naturally contaminated limnic sediment. This extraction methodology removed about 50% of the PCBs from the sediment. According to the equilibrium partitioning theory, organisms in that sediment should decrease their uptake from the sediment to the same extent, biota-to-sediment accumulation factors (BSAFs) thus remaining constant. Surprisingly, the BSAFs for 11 PCB congeners decreased some 40% for the selectively extracted sediment as compared to BSAFs for organisms dwelling in untreated sediment. The results were statistically significant at the 0.001 level using a paired t-test. This can only be interpreted so that selective SFE removed easily available PCBs preferentially, leaving more tightly bound PCBs behind. Hence, by fine-tuning extraction conditions, this methodology might be used to estimate bioavailable fractions by chemical means.
mesh_terms: D000818:Animals; D001682:Biological Availability; D002683:Chironomidae / Q000378:metabolism*; D025924:Chromatography, Supercritical Fluid; D004785:Environmental Pollutants / Q000032:analysis; D005618:Fresh Water; D019015:Geologic Sediments / Q000032:analysis*; D007814:Larva / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000493:pharmacokinetics*; D013548:Sweden
chemical_list: D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls