Electrochemical sensing of perfluorooctanoic acid in wastewater: Characterization of a molecularly imprinted polymer-based sensor

Stricter guidelines are progressively established to control the presence of perfluorooctanoic acid (PFOA) in
water bodies due to its toxicity and persistence in the environment. This study focused on the development of an
electrochemical sensor based on a molecularly imprinted poly(o-phenylenediamine) film to detect PFOA in
aqueous matrices. A comparative evaluation of sensor fabrication and analytical performance was performed on
gold (AuE) and glassy carbon (GCE) electrodes. Experimental conditions influencing electropolymerization
behavior, template removal, polymer morphology, and PFOA recognition were studied. Characterizations using
electrochemical techniques and Raman spectroscopy were correlated with analytical performance. These were
assessed in spiked buffer solution, yielding concentration-dependent trends over a wide dynamic range, with
detection limits of 23.0 and 20.2 ppt for the AuE and the GCE, respectively, meeting the sensitivity requirements
of current EU regulations. Selectivity was evaluated by studying sensor response in the co-presence of potential
interferents. The sensor was then tested on real samples collected from a wastewater treatment plant. A minor
matrix effect was registered in the filtered effluent, supporting the applicability of the sensor for rapid on-site
PFOA screening near regulatory thresholds.