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1A - Environmental Analytical Methods (MO8/4) Determination of partition coefficients (KDOC) between water and DOC for organic contaminants using negligible-depletion SPME. Haftka, Joris1, Parsons, John1, 1 University of Amsterdam, Amsterdam, North-Holland, Netherlands ABSTRACT- The occurrence of dissolved organic carbon (DOC) in soils and sediments can be an important factor in the sorption of organic contaminants. This partitioning behaviour over water and DOC is considered to be a regulating process linking mobility and bioavailability of organic compounds. Negligible-depletion SPME is used in this study to extract only a minor amount of freely dissolved PAHs from a DOC containing solution. This non-exhaustive extraction prevents shifting of the equilibria between DOC and water for an organic compound. The equilibrium partition constant (KDOC) can subsequently be calculated by GC-MS measurements of the free PAH-concentrations with varying DOC-concentrations. The optimisation of the extraction conditions will include determination of the equilibrium time, the ideal agitation conditions and the effect of pH and ionic strength using 7 Key words: sorption, Bioavailability, SPME, PAH |
m PDMS fibres to minimize the extracted amount. Further, the influence of the DOC-matrix will be studied as kinetics of extraction have shown to be different under non-equilibrium conditions. The partitioning experiments will be performed with DOC extracted from a selection of Dutch and Finnish sediments with different organic carbon content. The partition coefficient can ultimately be applied in a fate model incorporating absorption and desorption by DOC and uptake and elimination by organisms of the organic compounds studied.