A conductive polypyrrole based ammonium ion selective electrode

In view of the development of miniaturized sensor arrays, a solid-contact ammonium ion selective electrode has been investigated. A conductive polypyrrole film was electrochemically deposited on a glassy carbon surface and used as an internal solid contact layer between the sensing membrane and solid electrode surface. A systematic evaluation of the important parameters affecting the electromotive force (emf) response is presented. The performances of this solid-contact sensor were verified using a batch-mode measurement setup and a wall-jet flow cell system. The designed sensor exhibited excellent selectivity for the primary ion and a linear response over the pNH4+ range 1-5 with a slope of 56.3 mV decade(-1) . The sensor has a fast response and is relatively robustness, and was also used to determine ammonium concentrations in natural waters, with promising results.