“Forever chemicals” detection: A selective nano-enabled electrochemical sensing approach for perfluorooctanoic acid (PFOA)

Abstract

Perfluorooctanoic acid (PFOA) is a pollutant of emerging concern due to its high persistence, bioaccumulation, and potential toxicity. Numerous studies report its presence in water sources, soils, and food at sub-ppb levels. Here, we describe the design of an electrochemical sensor based on a self-assembled monolayer (SAM) of the 1H,1H,2H,2H-Perfluorodecanethiol (PFDT), into gold nanoparticles (AuNPs) electrodeposited on glassy carbon electrode (GCE) for PFOA detection. The GCE coated with AuNPs was characterized using scanning electron microscopy (SEM). The average size of AuNPs is estimated as 16 nm ± 07 nm, and the electrode surface coverage is 39 % ± 2 %. The calculated coverage of (Γ*) of chemisorbed PFDT molecules was found to be 8.26 × 10−10 mol cm−2. PFOA electroanalysis and quantification were performed by square wave adsorptive cathodic stripping voltammetry (SW-AdCSV) and measurements were verified by liquid chromatography-tandem mass spectrometry LC/MS-MS. We worked in a range of 100 to 5000 ppt, the PFOA concentration has a linear relationship with the stripping current (R2 = 0.996). The limits of detection (LOD) and quantification (LOQ) are 24 and 80 ppt, respectively. Analyses of tap and brackish samples performed by spiking tap water with known PFOA concentrations show precision and accuracy above 95 %. The nano-enabled electrode is stable for at least 200 cycles. The reproducibility across similarly prepared but different electrodes is above 97 %. The sensor shows the ability to quantify PFOA even in a matrix with other perfluoroalkyl substances as interferents, with a recovery percentage (Δi0–Δiint)/Δi0) within of 100 ± 10 %.