Balasuryia Damalka, Queral-Beltran Aina, Vick Tristan, Simpson Scott, Lacorte Silvia, Aga Diana S, Hoepker Alexander C
Department of Chemistry, University at Buffalo, The State University of New York (SUNY), Buffalo, New York 14260, United States.
Department of Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, Barcelona 08028, Catalonia, Spain.
Environ Sci Technol Lett. 2025 Aug 12;12(9):1238-1246. doi: 10.1021/acs.estlett.5c00688. eCollection 2025 Sep 9.
Accurate p values of per- and polyfluoroalkyl substances (PFAS) are urgently needed to improve predictions of their environmental fate, bioaccumulation, and removal, yet reliable experimental data remain scarce. Here, we determined the p values of 10 PFAS and three short-chain fluorinated acids (MFA: 2.58 ± 0.03; DFA: 1.22 ± 0.03, TFA: 0.03 ± 0.08) using F and H NMR-based chemical shift perturbation. Results were compared to prior experimental values, OPERA predictions (CompTox), and our COSMO-RS calculations. Measured p values include PFPrA (-0.18 to -0.54), PFOA (-0.27 ± 0.18), PFBS and PFOS (< -1.85), 6:2 FTS (<0.0), GenX (-0.20 ± 0.09), NFDHA (-0.32 ± 0.18), PFMPA (-0.26 ± 0.13), and 6:2 FTUCA (2.59 ± 0.11). Across C2, C3, and C8 homologues, PFCAs exhibit p values of approximately -0.2 to -0.3. Telomerization markedly reduces acidity: 5:3 FTCA (p = 4.05 ± 0.04) is >10-fold less acidic than PFOA, with COSMO-RS predicting similar effects from PFOS to 6:2 FTS. The dominant acidifying influence arises from CF groups at C1 and C2 near COOH or SOH. The unusually low p values for TFA, PFOA, and GenX reflect our low-MeOH, sorption-resistant NMR method. COSMO-RS consistently outperformed OPERA, underscoring the need for experimental benchmarks to improve predictive models for emerging PFAS.
迫切需要全氟和多氟烷基物质（PFAS）准确的pKa值，以改进对其环境归宿、生物累积和去除的预测，但可靠的实验数据仍然匮乏。在此，我们使用基于F和H NMR的化学位移扰动测定了10种PFAS和三种短链氟化酸（MFA：2.58±0.03；DFA：1.22±0.03，TFA：0.03±0.08）的pKa值。将结果与先前的实验值、OPERA预测值（CompTox）以及我们的COSMO-RS计算结果进行了比较。测得的pKa值包括PFPrA（-0.18至-0.54）、PFOA（-0.27±0.18）、PFBS和PFOS（<-1.85）、6:2 FTS（<0.0）、GenX（-0.20±0.09）、NFDHA（-0.32±0.18）、PFMPA（-0.26±0.13）和6:2 FTUCA（2.59±0.11）。在C2、C3和C8同系物中，全氟羧酸的pKa值约为-0.2至-0.3。端粒化显著降低了酸度：5:3 FTCA（pKa = 4.05±0.04）的酸度比PFOA低10倍以上，COSMO-RS预测从PFOS到6:2 FTS有类似的效果。主要的酸化影响来自COOH或SOH附近C1和C2处的CF基团。TFA、PFOA和GenX异常低的pKa值反映了我们的低甲醇、抗吸附NMR方法。COSMO-RS始终优于OPERA，强调了需要实验基准来改进新兴PFAS的预测模型。
