engleski

Fabrication of all-solid-state ammonium selective electrode on a paper substrate

Potentiometric ion-selective electrodes (ISEs) based on specific selective ionophores are nowadays important analytical tools for the detection of various ions. Among these sensors, ammonium ISEs have proven to be the most useful indicator electrodes for environmental monitoring [1, 2]. In this work, we present a novel planar solid-state ammonium selective electrode, which is made of low-cost and commercially available materials and suitable for mass production. For this purpose, an inkjet printed silver wire was used as an internal contact, while a mixture of graphite particles embedded in a polyvinyl butyral (PVB) matrix served as an ion-to-electron transducer, top-coated with a conventional ammonium ionophore I selective membrane. The resistance of the graphite-PVB layer, a key parameter of planar sensor viability, was evaluated by applying electrochemical impedance spectroscopy (EIS). Several transduction mixtures with different mass fractions of graphite to PVB were tested ; the lowest electron transfer resistance (15 kΩ) was achieved with a formulation consisting of 65 wt % graphite. Analytical performance of the array under steady-state conditions (potentiometric analysis) revealed linearity over a concentration range of 10–5 to 10–1 M, while flow injection analysis (FIA) showed linear response range from 10–4 to 10–1 M. A near- Nernstian slope of 58.34 mV/decade and 60.91 mV/decade is achieved using both techniques, respectively. The proposed electrode is miniaturized, can be easily integrated into portable devices of various sizes and shapes, and has potential application in monitoring NH4+ content in water samples over a wide range of pH values.

ammonium-selective membrane ; solid contact ion-selective electrode ; potentiometric sensor ; flow injection analysis

nije evidentirano