Indirect determination of cyanide ion and hydrogen cyanide by adsorptive stripping voltammetry at a mercury electrode

An indirect voltammetric method is described for determination of cyanide ions and hydrogen cyanide, using the effect of cyanide on cathodic adsorptive stripping peak height of Cu-adenine. The method is based on competitive Cu complex formation reaction between adenine at the electrode surface and CN⁻ ions in solution. Under the optimum experimental conditions (pH=6.42 Britton-Robinson buffer, 1×10⁻⁴ M copper and 8×10⁻⁷ M adenine), the linear decrease of the peak current of Cu-adenine was observed, when the cyanide concentration was increased from 5×10⁻⁸ to 8×10⁻⁷ M. The detection limit was obtained as 1×10⁻⁸ M for 60 s accumulation time. The relative standard deviations for six measurements were 4 and 2% for the cyanide concentrations of 5×10⁻⁸ and 2×10⁻⁷ M, respectively. The method was applied to the determination of cyanide in various industrial waste waters such as electroplating waste water and also for determination of hydrogen cyanide in air samples.