An XPS investigation of silver bromide-coated ion-selective electrodes |
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| Authors: | C. A. Strydom J. F. Van Staden H. J. Strydom |
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| Affiliation: | 1. Department of Chemistry, University of Pretoria, Pretoria, 0002, South Africa;2. Mikomtec, CSIR, P.O. Box 395, Pretoria, 0002, South Africa |
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| Abstract: | XPS data of AgBr-coated ion-selective electrodes exposed to high concentrations of Ag+, Cl−, Br−, I−, and NH3 revealed a change in the surface properties of the original electrode. A 40 min to one week exposure of the silver bromide ion-selective electrode surface to solutions containing high concentrations of chloride ions leads to the formation of a mixed halide layer, as the chloride ions are incorporated in the surface. Exposure to high concentrations of iodide-containing solutions results in a new silver iodide layer on top of the original silver bromide laver. Silver ions diffuse to the newly formed layers. NH3 results in the rapid degradation of the AgBr surface as the diamine complex, Ag(NH3)+2, is formed. |
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