Determination of low levels of cyanide with a silver/silver sulphide wire electrode

A silver/silver sulphide electrode is prepred quickly by holding a cleaned silver wire in vapours from molten sulphur. In 1000–10 mg l^?1 cyanide solutions, the electrode exhibits a linear E/log C_CN function which becomes slightly sinusoidal for 10–0.1 mg l^–1 cyanide. The average slope is slightl super-Nerstian (10 mV/decade concentration). The applicability of the electrode is demonstrated for the determinations of microgram quantities of water-soluble cyanide from the Prussian blue pigments which are constituents of externally applied cosmetics. The home-made electrode provides results agreing with those obtained with commercially available electrodes.