Fabrication of an All-Solid-State Ammonium Paper Electrode Using a Graphite-Polyvinyl Butyral Transducer Layer

Abstract

A planar solid-state ammonium-selective electrode, employing a composite mediator layer of graphite particles embedded in a polyvinyl butyral matrix on top of an inkjet-printed silver electrode, is presented in this paper. The effect of graphite powder mass fraction on the magnitude of the potentiometric response of the sensor was systematically verified using a batch-mode and a flow injection measurement setup. Under steady-state conditions, the paper electrode provided a Nernstian response of 57.30 mV/pNH4 over the concentration range of 10−5 M to 10−1 M with a detection limit of 4.8 × 10−6 M, while the analytical performance of the array in flow mode showed a narrower linear range (10−4 M to 10−1 M; 60.91 mV/pNH4 slope) with a LOD value of 5.6 × 10−5 M. The experimental results indicate that the prepared electrode exhibited high stability and fast response to different molar concentrations of ammonium chloride solutions. The pH-response of the paper NH4-ISE was also investigated, and the sensor remained stable in the pH range of 2.5–8.5. The potentiometric sensor presented here is simple, lightweight and inexpensive, with a potential application for in-situ analysis of environmental water samples.