In soils and sediments contaminated by hydrophobic organic compounds, the total concentrations are less indicative of potential exposure than the associated freely dissolved concentrations or chemical activities. A wide range of equilibrium sampling devices have been developed and applied for the measurement of bioavailability of hydrophobic organic chemicals. Also, the equilibrium sampling in silicone is increasingly applied within the bioaccumulation research.
In a study published in the February 1 issue of Environmental Science & Technology, a team of researchers from the University of Eastern Finland and Aarhus University developed two equilibrium sampling techniques for PCBs in soils and sediments. They combine simplicity with good analytical performance and were specifically designed for their application to very complex media.
Two equilibrium methods were applied to PCB-contaminated soil and sediment, and directly calibrated with respect to equilibrium partitioning concentrations in lipids: (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.
Equilibrium partitioning concentration in lipids 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 equilibrium partitioning concentrations in lipids 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.
For further information, please contact Kimmo Mäenpää, PhD,
+358 13 251 3545; fax: +358 13 251 3590; e-mail: email@example.com
Kimmo Mäenpää, Matti T. Leppänen, Fredrik Reichenberg, Kaisa Figueiredo, and Philipp Mayer. Equilibrium Sampling of Persistent and Bioaccumulative Compounds in Soil and Sediment: Comparison of Two Approaches To Determine Equilibrium Partitioning Concentrations in Lipids. EnvironmentalScience & Technology, 2011, 45 (3), pp 1041–1047. DOI: 10.1021/es1029969.
Artikkelin kirjoitusvuosi: 2011Takaisin tämän vuoden artikkeleihin