A sensitive and selective amperometric determination of perfluorooctanesulfonic acid on MoTiAlC MXene precursor-modified electrode.

Various commercial and industrial products widely use highly toxic eight-carbon-chain perfluorooctanesulfonate (PFOS), posing a significant threat to the health of living organisms. In this study, the electrochemical detection of PFOS was achieved by developing a carbon paste electrode (CPE) using MoTiAlC MAX phase. MoTiAlC was synthesized and directly used to construct the CPE. The electrochemical performance of the prepared sensor was tested using various electrochemical techniques, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and amperometric titration. The developed electrochemical sensor exhibited two linear ranges from 0.001-0.09 μM and from 1.1-62.6 μM, with a detection limit of 0.04 nM. The sensor demonstrated high sensitivity, measuring 145.1 μA μM cm, and a response time of 5 seconds for PFOS quantification at a working potential of 0.3 V. Additionally, the sensor demonstrated outstanding resistance to typical interfering chemicals. The applicability and reliability of the developed sensor for PFOS determination were further tested in real samples, yielding recoveries in the range of 92.6-107.7%, with relative standard deviation (RSD) values between 1.8% and 3.7%. The MoTiAlC MAX phase-based electrochemical sensor is simple, rapid, sensitive, and cost-effective, making it a promising approach for the quantification of PFOS in environmental water and soil samples.