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The C–F alkyl structural backbone of per- and polyfluoroalkyl substances makes this class of molecules resistant to heat and degradation, leading to their high persistence and mobility in the environment and bioaccumulation in the tissues of living organisms. In this study, 15 PFAS with an alkyl chain length from C4 to C14, currently monitored by the U.S. Environmental Protection Agency (EPA), were preconcentrated by solid-phase microextraction (SPME) and analyzed by liquid chromatography-tandem mass spectrometry. The adsorption and desorption mechanisms of PFAS onto ion-exchange extraction phases was evaluated to understand the extraction process of PFAS from various environmental matrices under different conditions. This was achieved using two SPME geometries, namely fibers and thin films. The use of thin films resulted in a twofold improvement in extraction efficiency compared to fibers, especially for the short-chain PFAS. Methanol:water (80:20, v/v) was chosen as the optimized desorption solution, with ammonium formate added to minimize carryover. Extraction time profiles for both SPME geometries showed faster equilibration with thin films (30 min) compared to fibers (90–120 min). The linear dynamic range obtained with this method using fibers and thin films ranged from 10 to 5000 ng L􀀀 1 and 2.5–5000 ng L􀀀 1, respectively, with acceptable accuracy (70–130%) and precision (<15%). LOD ranged within 2.5–10 ng L􀀀 1 for fibers and 0.01–0.25 ng L􀀀 1 for thin films. Investigating the factors affecting PFAS recovery in complex samples enabled the quantitative assessment of PFAS contamination in various environmental water samples such as seawater, melted snow and biospecimens like human plasma. A 96-SPME holder was used for validation, which is compatible with sampling in 96-well plates and ensures high throughput in the analysis of real samples. The total concentration of PFAS detected in seawater and snow was 51.3 ng L􀀀 1 and 16.4 ng L􀀀 1, respectively. 

The ubiquitous presence and persistence of per‐ and polyfluoroalkyl substances (PFAS) in the environment have raised concerns in the scientific community. Current research efforts are prioritizing effective PFAS remediation through novel sorbents with orthogonal interaction mechanisms. Recognized sorption mechanisms between PFAS and sorbents include hydrophobic, electrostatic, and fluorine‐fluorine interaction. The interplay of these mechanisms contributes significantly to improved sorption capacity and selectivity in PFAS separations. In this study, a primary/secondary amine‐functionalized polystyrene‐divinylbenzene (Sepra‐WAX) polymer was modified to create a fluorinated WAX resin (Sepra‐WAX‐KelF‐PEI). The synthesis intermediate (Sepra‐WAX‐KelF) was also tested to assess the improvement of the final product (Sepra‐WAX‐KelF‐PEI). The adsorption capacity of Sepra‐WAX, Sepra‐WAX‐KelF, and Sepra‐WAX‐KelF‐PEI, and their interactions with PFAS were evaluated. The effect of pH, ionic strength, and organic solvents on PFAS sorption in aqueous solution was also investigated. The sorbents showed varied adsorption capacities for perfluorooctanoic acid, perfluoropentanoic acid, perfluoro‐n‐decanoic acid, and hexafluoropropylene oxide dimer acid, with the average extraction capacity of the four analytes being Sepra‐WAX‐KelF‐PEI (523 mg/g) > Sepra‐WAX (353 mg/g) > Sepra‐WAX‐KelF (220 mg/g). Sepra‐WAX‐KelF‐PEI provided the highest adsorption capacity for all analytes tested, proving that the combination of electrostatic and hydrophobic/fluorophilic interactions is crucial for the effective preconcentration of PFAS and its future applications for PFAS remediation from aqueous solutions.