(7) Due to the limited data available on basic physical–chemical properties of the majority of these PFAS, such as dissociation constants and partition coefficients, exposure assessment models such as global fate models and toxicokinetic models may provide uncertain outcomes. (1−6) Many PFAS are ionogenic in the common pH range of field conditions and biotic tissues and act as surfactants. Widely varying structures of PFAS have been detected ubiquitously in humans and the environment. Perfluoroalkyl substances (PFAS) are highly persistent chemicals and abundantly used for many purposes and, therefore, reach the environment via all kinds of waste streams. The LC 50,narc coincides with the lowest reported acute LC 50 values for several anionic surfactants but were on average about an order of magnitude lower. Dividing the critical narcotic membrane burden of 100 mmol/kg by the experimental K MW predicts lethal baseline toxicity concentrations (LC 50,narc). COSMO-RS based molecular calculations of K MW aligned with SSLM K MW values for hydrogenated anions with C 8–C 14 alkyl chains but strongly underestimated CF 2 and CH 2 unit increments for C 4–C 8 based anions. Intrinsic partition ratios determined on a phospholipid coated HPLC column (IAM-HPLC) closely aligned with SSLM K MW values. PFSAs sorbed 0.90 log units stronger than analogue PFCAs C xSO 4 sorbed 0.75 log units stronger than analogue C xSO 3 anions. A sorbent dilution assay with solid supported lipid membranes (SSLM) showed consistent CF 2 unit increments of 0.59, and CH 2 unit increments of 0.53, for the log K MW of perfluorinated and hydrogenated anions, respectively.
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This study determined the sorption affinity to artificial phospholipid membranes ( K MW) for series of perfluorinated carboxylates (PFCAs), perfluorinated sulfonates (PFSAs), alkyl sulfates (C xSO 4), and 1-alkanesulfonates (C xSO 3).