Electrochemical Detection of Perfluorooctanoic Acid by a Zn–Terpyridine and Nafion‐Modified Glassy Carbon Electrode

Perfluorooctanoic acid (PFOA), a persistent organic pollutant, poses significant environmental and health risks due to its widespread occurrence in water sources and resistance to degradation. This study investigates zinc(II) terpyridine (Zn–tpy) complexes as molecular receptors for PFOA, demonstrating capture via carboxylate binding to Zn(II) with concomitant changes to nuclear magnetic resonance (NMR) and absorbance spectra. The capture capability and redox properties of the complexes were used to develop an electrochemical method for PFOA at a glassy carbon (GC) electrode modified with a thin discontinuous Nafion overlayer that assists with preconcentration at the sensor. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square‐wave voltammetry (SWV) were used to characterize the modified electrode. The electrode gave a limit of detection (LOD) of 0.407 pM and a linear range of 0.5–10 pM, with short‐term intra‐ and interelectrode relative standard deviations (RSD) of 0.94% and 2.02%. Recoveries of 96%–98% were obtained for Cork tap water spiked with PFOA after 1:100 dilution in phosphate‐buffered saline (PBS). The preliminary data suggests Zn–tpy complexes in combination with selective coatings may be applicable for class‐selective electrochemical detection of perfluoroalkyl carboxylic acids, exemplified herein using PFOA.