title: Equilibrium sampling of persistent and bioaccumulative compounds in soil and sediment: comparison of two approaches to determine equilibrium partitioning concentrations in lipids.
abstract: The equilibrium sampling in silicone is increasingly applied to measure freely dissolved concentrations and chemical activities within bioaccumulation research of hydrophobic organic chemicals. Two equilibrium methods were applied to PCB-contaminated soil and sediment, and directly calibrated with respect to equilibrium partitioning concentrations in lipids (C(lipid,partitioning)): (i) Solid phase microextraction in the headspace above the sample (HS-SPME) required optimization for its application to PCBs, and it was calibrated above external partitioning standards in olive oil. (ii) Equilibrium sampling with internally coated glass jars with varying thicknesses of silicone (PDMS) resulted in proportionality between coating and analyte mass, which confirmed several validity criteria. C(lipid,partitioning) was here determined as product of PDMS concentration and PDMS to lipid partition ratio. The results of the two methods were in good agreement and thus validated each other. Finally, the coated glass jar method was applied to field sediment containing invertebrates, which lead to C(lipid,partitioning) that were about two times higher than measured lipid-normalized concentrations in the organisms. Temperature differences and animal lipid structure were discussed as possible reasons for this discrepancy. Both methods combine high analytical performance, reduced equilibration times and new calibration possibilities, which makes them suited for bioaccumulation research and environmental monitoring.
authors.affiliation: Department of Biology, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland. kimmo.maenpaa@uef.fi
authors.forename: Kimmo
authors.initials: K
authors.lastname: Määenpää
authors.forename: Matti T
authors.initials: MT
authors.lastname: Leppänen
authors.forename: Fredrik
authors.initials: F
authors.lastname: Reichenberg
authors.forename: Kaisa
authors.initials: K
authors.lastname: Figueiredo
authors.forename: Philipp
authors.initials: P
authors.lastname: Mayer
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry*; D007700:Kinetics; D008055:Lipids / Q000737:chemistry*; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry; D011078:Polychlorinated Biphenyls / Q000032:analysis; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D052616:Solid Phase Extraction
chemical_list: D008055:Lipids; D000069463:Olive Oil; D010938:Plant Oils; D012987:Soil; D012989:Soil Pollutants; D011078:Polychlorinated Biphenyls