All retention times measured with 10 mM NH4CH3COO and 0.2 mM NH3 for PFAS and non-PFAS are tabulated in Table . For each compound, k data were obtained at 2-7 concentrations of MeOH in the eluent. No significant retention was obtained for butyric acid (BA), the smallest test compound, even at φMeOH of 0. Conversely, no peak appeared for long-chain compounds within the run time (2-3 h) at low φMeOH. Identification of FTUCAs was unclear, possibly due to the use of a single quad MS in this work and peak overlap with FTCAs. No peak was obtained for 11Cl-PF3OUdS due to inadequate m/z setting for this chemical, which became apparent after all measurements. In the end, we obtained k data for 39 PFAS and 20 nonfluorinated surfactants at least for two values of φMeOH.