Biomimetic extraction as a tool to identify chemicals with high bioconcentr- ation potential : An illustration by two fragrances in sewage treatment plant effluents and surface waters

The Empore disk biomimetic extraction procedure is a method to estimate total body residues (TBRest) in biota after exposure to complex mixtures of organic chemicals in water. Except for highly hydrophobic compounds, the extraction procedure is nondepletive by using an excess of water. Therefore, it is a selective extraction process of the bioavailable fraction of compounds. The extent, to which compounds are extracted, depends on their hydrophobicity. Consequently, compounds that only have a minor contribution to the total amount in exhaustive extracts can become very prominent in the biomimetic extracts. Bioconcentration is also a process that depends primarily on hydrophobicity. In this study the method is applied to selectively focus on compounds with a high bioconcentration potential. This feature is illustrated by data on two fragrances (HHCB and AHTN) in effluents of municipal sewage treatment plants and several types of surface water. Although estimated aqueous concentrations of both AHTN and HHCB ranged from about only 1 ng/L in clean surface water to 500 ng/L in the effluents of sewage treatment plants, the contribution of these two compounds together to the total amount of extracted compounds varied from 1 to 23% for surface waters and from 5 to 22% for effluents.