Potentiometric Flow-Injection Analysis of Alkali and Alkaline Metals with a Tungsten Oxide Coated Nafion Film Sensor

Potentiometric flow-injection analysis of alkali and alkaline metals was possible using a novel type of electrochemical sensor based on tungsten oxide wire coated Nafion electrode. The response characteristics of a tungsten oxide coated Nafion sensor for alkali and alkaline metals were investigated bypotentiometric flow-injection measurement. It was found that ion exchange preconcentrated metals by electrostatic interaction and also excluded the anion interference in the presence of Nafion film on the surface of the electrode. This sensor gave a linear response in the range of 4 × 10-5-1 × 10-2 M with detection limits of 10-6 M. The slopes of 39.2 and 44.4 mV/ decade for the K+ and Ca2+ were obtained. Compared to bare electrode, the coated Nafion sensor offered a fast response time (<10 s), a stable baseline, and no anion interference. © 1997 John Wiley & Sons, Inc.