Novel solid-state ammonium ion potentiometric sensor based on zirconium titanium phosphate ion exchanger

Preparation, characterization and applications of a novel long life ammonium ion membrane sensor based on zirconium titanium phosphate (ZTP) ion exchanger are described. The sensor displays a useful analytical response with excellent reproducibility, good precision, low detection limit and applicability over a wide range of ammonium ion concentration (1.2 x 10(-5)-1.0 M). It also offers the advantages of significantly high thermal stability and resistivity towards redox agents and strong mineral acids. Using a gas diffusion dialyzer/flow-injection system, under optimized conditions, the ZTP membrane based sensor provides a throughput of 30 samples per hour with excellent selectivity for ammonium ion over most common cations. The average recovery of 7-140 mug ml(-1) NH3-N is 101.3 +/- 1.6% and the overall system has the advantages of simple construction, low cost, fast response time, reliability and automation feasibility. (C) 2001 Elsevier Science B.V. All rights reserved.