Analytical Sciences

Coated Wire Silver-Ion Selective Electrode Based on a N,N′-Bis(2-thienylmethylene)-1,2-diaminobenzene

Hamid R. ZARE,* Masoud SALAVATI-NIASSARY,** Farkhondeh MEMARZADEH,* Mohammad MAZLOUM,* and Navid NASIRIZADEH*

*Department of Chemistry, Yazd University, Yazd, 89195-741, Iran
**Department of Chemistry, Kashan University, Kashan, Iran

A novel membrane coated platinum-wire electrode (MCPWE) based on N,N′-bis(2-thienylmethylene)-1,2-diaminobenzene (BTMD) for highly selective determination of Ag⁺ ion has been developed. The influences of membrane composition and pH on the potentiometric responses of electrode were investigated. The potentiometric responses are independent of the pH of the test solution in the range of 5.0 - 9.0. The electrode shows a linear response for Ag⁺ ion over the concentration range of 1.0 × 10^-6 to 1.0 × 10^-1 M with a lower detection limit of 6.0 × 10^-7 M. The electrode possesses a Nernstian slope of 59.7 mV decade^-1 and a fast response time of ≤ 17 s and can be used for at least 2 months without any observable deviation. The proposed electrode displayed very good selectivity for Ag⁺ ion with respect to NH₄⁺ and alkali, alkaline earth and some common transition metal ions. The practical utility of the electrode has been demonstrated by its use as the indicator electrode in the potentiometric titration of an AgNO₃ solution with a NaI solution and in determination of the silver content of a developed radiological film.

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