Spectrophotometric determination of total cyanide in surface waters following ultraviolet induced photodecomposition

Abstract

A simple and sensitive spectrophotometric method for the determination of total cyanide in surface waters is described. Sodium hexacyanoferrate(II) can be found in surface waters owing to its use as an anti-caking agent in road de-icing salts. The method is based on the decomposition of complexed cyanide to free cyanide by exposure to short wave ultraviolet (UV) light. The sample is then analysed for free cyanide by a method based on the Konig reaction. The optimum sample UV irradiation time and the effect of NaCl on the spectrophotometric method were investigated. The method was applied to various surface water samples using standard additions to eliminate the interference from high salt concentrations and background sample colour in some surface water samples.