Electrochemical Detection of Thioether-Based Fluorosurfactants in Aqueous Film-Forming Foam (AFFF)

Using cyclic voltammetry (CV) and impedance (IMP), we report a simple approach to detect new fluorosurfactant ingredient formulated in aqueous film-forming foam (AFFF), specifically the thioether-based one. First, we employ ion chromatography (IC) to identify all possible elements with the help of chemical oxidation and infrared spectrum (IR) to identify all possible functional groups. We thus propose a possible thioether-based molecular structure of fluorosurfactant formulated in AFFF. By studying the self-assembled monolayer (SAM) formed on gold (Au) surface via thio-Au bond, we establish a relationship between the SAM density and the amount of the thioether-based fluorosurfactant for the AFFF detection. Solid phase extraction (SPE) and nanoporous Au electrode are employed to enhance the sensitivity. Consequently, a detection limit of 10 ppb (v/v) has been achieved for AFFF-spiked tap water sample.