An ultra-sensitive molecularly imprinted polymer (MIP) and gold nanostars (AuNS) modified voltammetric sensor for facile detection of perfluorooctance sulfonate (PFOS) in drinking water

Perfluorooctance sulfonate (PFOS) is one of the most studied Per-and-polyfluoroalkyl substances (PFAS) due to its relatively high environmental ubiquity and toxicity. This study presented an ultra-sensitive voltammetric sensor for the detection of PFOS in tap water based on a glassy carbon electrode (GCE) modified with a thin coating of gold nanostar (AuNS) and electropolymerized molecularly imprinted polymer (MIP). The AuNS coating helps to enhance the voltammetric response of blank signal intensity regarding the Fe2+ oxidation of the selected ferrocenecarboxylic acid (FcCOOH) redox probe; meanwhile, the statistical optimization of the MIP layer offers a higher peak change. Analytical results indicated the sensor could detect PFOS with an LoD and LoQ of 0.015 and 0.041 nM (i.e., 7.5 and 20.5 ppt), respectively. Moreover, it showed comparable analytical performance in tap water with the U.S. Environmental Protection Agency (EPA) method (i.e., Method 537.1). Interfering effects of approximately 10% underestimation were observed when samples contained equimolar perfluorobutanoic Acid (PFBA) or perfluorobutanesulfonic acid (PFBS). Additionally, common interferents in drinking water sources, such as humic acid and chloride ion, showed minor influence in the voltammetric response in terms of accuracy and reproducibility.