Portable and ultrasensitive detection of traces of water in alcoholic solvents by a polypyrrole-modified screen-printed electrode

In industrial production, the water content in alcoholic solvents is crucial for determining the quality and yield of the final products, and excessive water can potentially lead to accidents. However, in-situ, rapid, and accurate detection of trace amounts of water in alcoholic solvents has been a persistent challenge. Herein, we report a screen-printed electrode (SPE) modified with electroactive polypyrrole (PPy@SPE), which enables rapid and ultrasensitive quantification of water content in four alcoholic solvents. The amine groups on PPy provide hydrogen bonding sites, which, in conjunction with the rough surface of the SPE, enhance the adsorption of alcohol molecules and decrease the electrochemical response of the PPy@SPE due to the hindrance of charge transfer. Under optimal conditions, the PPy@SPE can detect water levels as low as 0.02 %, 0.01 %, 0.01 %, and 0.01 %, in methanol, ethanol, n-propanol, and isopropanol, respectively, and can be reused for six cycles or more. Furthermore, the capability for in-situ detection of water in alcoholic solvents was demonstrated by integrating the PPy@SPE with a miniaturized potentiostat. With the advantages of being ultrasensitive, robust, low-cost, and facile detection, this sensor is potentially a valuable tool for on-site water content monitoring in chemical industries.