Nafion-modified Carbon Based Sensor for Soil Potassium Detection

In the present investigation, we report a voltammetric sensor based on Nafion modified screen printed carbon ink functionalized with 4-aminobenzo-18-crown-6 ether for the detection of soil potassium. The potassium is one of the major nutrient elements required by the plants and is critical for the crop productivity. The selective and sensitive assay is based on recording change in current signal of a positively charged redox probe, hexammineruthenium(III)chloride in the absence and presence of K+ ion in solution. The sensing interface is highly stable and reproducible for detection of K+ ion a under a wide range of concentration 1 to 500 ppm. The detection sensitivity over a wide concentration range was achieved by altering the concentration of redox species. Mechanistically, the recognition properties of 4-aminobenzo-18-Crown-6 covalently bound to the Nafion on carbon surface was found to be selective for potassium ion over sodium, ammonium and calcium ion. Potassium recognition through host-guest binding of crown ether derivative and proposed simplicity of fabrication protocol makes the systems highly promising for real-time applications in soil analysis.