Silver Hexacyanoferrate Film Directly Modified Electrode as a Potentiometric Sensor for Potassium Ion

Abstract

A chemically modified electrode (CME) was fabricated by direct modification of a silver electrode with a thin film of silver hexacyanoferrate. The modified electrode was used as a potentiometric sensor for the determination of potassium ion. The sensor exhibits a response to potassium ion in a wide concentration range from 8.0 × 10⁻⁵ to 1.0 M with a low detection limit of 4.0 × 10⁻⁵ M. The potassium-selective electrode has a relatively short response time. It has a good sensitivity with a near-Nernstian slope of 53–57 mV/decade and good selectivity in the presence of possible interferences. The electrode response is highly sensitive to some controllable parameters mainly the thickness of electroactive film which is controlled by the charge passed in the cell during the deposition of the film. Stability of the directly modified electrode and its potentiometric response were also investigated during long-term usage, which were indicative of the possibility of the potassium-selective electrode for using in a long period.

Keywords:

• Silver hexacyanoferrate
• Direct modification
• Potentiometry
• Ion-selective electrode
• Potassium ion