Studies with chromium ferricyanide epoxy resin-based membranes

The solid membrane of chromium ferricyanide in epoxy resin has been used as a silver sensitive electrode. The electrode response to silver ions is non-Nernstian, but a linear plot has been obtained in the concentration range 10−1-10−3M with a slope of 46 mV per decade of activity. The response time of the electrode is a few seconds and potentials generated are reproducible. The electrode is not specific to silver ions but can nevertheless be used in presence of Hg2+, Zn2+ and Cd2+. Anions show no interference. Silver can be estimated even in the presence of interfering ions by potentiometric titration using the membrane as an end point indicator electrode.