To determine the three descriptors, a minimum of three k' and K data are required for a given PFAS compound. The data used here were: k' measured for 60 PFAS in this study, KHxd/w for 21 PFAS, Kow for 12 PFAS (see Results and Discussion section), and Koa for 3 PFAS. Note that Kaw for 21 PFAS in ref 5 was not considered here to avoid duplicate data use, as these data were derived from KHxd/w and KHxd/air through the thermodynamic cycle calculation.