You are here:
Measurement of Octanol-Water and Butanol-Water Partition Coefficients for Per- and Poly-fluorinated Alkyl Substances.
Citation:
Sluka, H., T. Shonrock, I. Mundy, L. Burkhard, Dave Mount, AND W. Backe. Measurement of Octanol-Water and Butanol-Water Partition Coefficients for Per- and Poly-fluorinated Alkyl Substances. SETAC North America, Pittsburgh, PA, November 13 - 17, 2022. https://doi.org/10.23645/epacomptox.21565308
Impact/Purpose:
Poster presented to the Society of Environmental Toxicology and Chemistry (SETAC) annual meeting November 2022. This will summarize measured bioconcentration factors (BCFs) for per- and polyfluorinated alkyl substances (PFAS) in Hyalella azteca, and other small aquatic invertebrates as data becomes available. In ongoing toxicity testing with PFAS, BCF is necessary for inferring mechanism(s) of toxicity by relating water-column effect concentrations to critical body burden. This work will thus aid PFAS toxicity testing in H. azteca at ORD’S Duluth, MN laboratory by furthering the understanding of toxic mechanisms and development of structure-toxicity relationships. The intended audience is ecotoxicologists and risk assessors from government, industry, and academia at an international professional conference. This work is taking place under the Safe and Sustainable Water Resources National Program, specifically SSWR 3.2.2. DISCLAIMER: The views expressed in this poster are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.
Description:
Per-and-poly-fluorinated alkyl substances (PFASs) are a diverse class of synthetic compounds found ubiquitously in the environment and are shown to cause toxic effects in aquatic organisms. Solvent-water partitioning coefficients, such as octanol-water (Kow), are fundamental properties that are widely used to predict or model environmental fate, bioaccumulation, and toxicity. However, agreement between solvent-water partitioning coefficients for PFASs derived from different computational methods is poor, owing to the challenges of modeling chemicals that are fluorinated and often ionized at ambient pH. EPA’s CompTox Chemical Dashboard reports Log Kow values from various models for perfluorooctane sulfonamide (PFOSA), ranging from 5.02 (OPERA) to 7.64 (ACD/Labs) with similar or greater variability observed for other common PFASs. High-quality measured Kow values for PFASs are also rare, leaving a critical data gap that prevents evaluation of model performance. To address this data gap, we are experimentally measuring Kow values for a range of PFASs within the homologue series of carboxylic acids, sulfonic acids, sulfonamides, and fluorotelomer sulfonates. Measurements are made by OECD Slow Stir Method 123, with quantitation of both aqueous and organic phases by HPLC-MS and/or HPLC-MS/MS. In addition to directly measuring Kow, we are also exploring the use of the butanol-water partition coefficient (Kbw) as a predictor of Kow, a relationship that has proven robust for a number of other chemical classes but has not yet been unexplored for PFASs. Measurement of Kbw as a predictor of Kow has some advantages, including faster equilibration kinetics, and easier quantification in the water phase due to butanol being less hydrophobic compared to octanol.
URLs/Downloads:
DOI: Measurement of Octanol-Water and Butanol-Water Partition Coefficients for Per- and Poly-fluorinated Alkyl Substances.
SLUKA_SETAC_POSTER_FINAL_SUBMITTED. .PDF (PDF, NA pp, 818.491 KB, about PDF)