Rapid and Direct Perfluorooctanoic Acid Sensing with Selective Ionomer Coatings on Screen-Printed Electrodes under Environmentally Relevant Concentrations

Per- and polyfluoroalkyl substances (PFASs) pose a significant health threat to humans at trace levels. Because of its ubiquity across the globe, there have been intense efforts to rapidly quantify PFASs in the environment while also mitigating their release. This work reports an electrochemical sensor with a selective perfluorinated anion exchange ionomer (PFAEI) coating for direct sensing of perfluorooctanoic acid (PFOA)─a type of PFAS. Notably, the sensor operates without the need of redox probes and has a limit of detection around 6.51 ± 0.2 ppb (15 nM) in buffered deionized water and drinking water. By testing the sensor with different ionomer electrode coatings, it was inferred that the PFAEI favors PFOA anions over other competing anions in solution through a combination of electrostatic and van der Waal interactions.