Oil dispersion of AgI/Ag₂S salts as a new electroactive material for potentiometric sensing of iodide and cyanide

Oil dispersion of AgI/Ag2S salts as a new electroactive material for potentiometric sensing of iodide and cyanide is reported. This type of material offers attractive features which can be used in the future for various chemical and biological modifications. The composition of the sensing membrane was optimized to be 5:1 (w/w) silver salt to paraffin oil. The sensor had a Nernstian response to iodide with a slope of +57.5 ± 1.4mV per decade (25°C), a linear working range of pI- 2.0-6.5 and a fast response time of 30s. The sensor, likewise, exhibited high sensitivity (69.1 ± 4.1mV per decade) to cyanide ions, excellent linearity (r = 0.999), a linear working range of pCN- 2.6-4.7 and an average response time of 1min. The sensor can be used repeatedly in measuring iodide solutions without the need for surface renewal and polishing. However, in the presence of cyanide solutions, it gives reproducible results only upon renewal of the surface. © 2004 Elsevier B.V. All rights reserved.