Comprehensive Validation of the Adsorbable Organic Fluorine Analysis and Performance Comparison of Current Methods for Total Per- and Polyfluoroalkyl Substances in Water Samples

Per- and polyfluoroalkyl substances (PFASs) are widely detected in the environment, while a large number of them cannot be identified and/or quantified by current analytical methods. As a surrogate total PFAS analysis, the adsorbable organic fluorine (AOF) method was improved and validated in this study. The improved method has limits of detection and quantification of 300 and 400 ng/L, respectively, more sensitive than the previously reported AOF methods. AOF recovery for 29 individual PFASs ranged 53-113%, while three short-chain PFASs yielded lower recovery (19-39%) due to low adsorption efficiency. Recovery for PFAS mixtures in different environmental water matrices was 64-84%, and was negligibly impacted by the presence of fluoride, dissolved organic matter, or other matrix constituents. The validated method was applied to different environmental water samples, and AOF data were compared to results from other total PFAS analyses, including total fluorine, extractable organic fluorine, total oxidizable precursors, and summed individual PFASs. The fluorine contents from targeted PFAS analysis only contributed 0.4-29% of AOF concentrations in all except two samples, indicating the significance of AOF for estimating unknown PFAS concentrations, screening PFAS contamination, and assessing PFAS exposure.