Analytical Sciences

Potentiometric Performance of Silver Ion-Selective Electrodes Based on Tridentate Schiff Base Derivatives

Masato UEDA, Takahiro SAITO, Keiichi FUJIMORI, Takayo MORIUCHI, and Yasuhiko SHIBUTANI

Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology, 5-16-1, Omiya, Asahi, Osaka 535-8585, Japan

To examine the directivity for improving the silver ion discrimination ability of a Schiff base, three kinds of tridentate ligands were synthesized and compared with the similar quadridentate ligand as the silver ionophore. Among the Schiff base derivatives tested, 3-(2-pyridylethylimino)-2-butanoneoxime, having one oxime and a pyridine substituent, was found to be the best ionophore for a silver-ion electrode. The electrode based on this derivative exhibited good silver-ion selectivity, -log K^pot_Ag⁺,K⁺ = 3.8, comparable to that of a quadridentate Schiff base, N,N′-bis(2′-hydroxyimino-1′-phenylpropyleden)-1,3-propanediamine, reported previously, except for a pseudo Nernstian response (35.6 mV decade^-1) with a wide silver-ion activity change in the activity change from 5.0 × 10^-7 to 7.9 × 10^-2 mol dm^-3.

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