Solid-state mercury(I) chloride electrode for determining 0.1–1.0 µg ml–1 levels of chloride in boiler water and other high-purity waters

Abstract

A solid-state electrode based on mercury(I) chloride and mercury(II) sulphide has been developed for determining chloride concentrations of 0.01–1.0 µg l^–1 in boiler water. The greater sensitivity of the electrode compared with that of silver-silver chloride electrodes enables concentrations as low as 0.01 µg ml^–1 to be determined by a simple manual technique. The total standard deviations at chloride concentrations of 0.5, 0.1 and 0.01 µg ml^–1 were 0.025, 0.005 and 0.015 µg ml^–1, respectively. The electrode can be prepared easily in the laboratory from commercially available materials and a Růžička Selectrode. The only significant interference is from iron(III) ions and this interference can be eliminated by adding fluoride ions to the sample.