Determination of cyanide concentration by chronoamperometry, cyclic voltammetry and fast Fourier transform electrochemical impedance spectroscopy

In this research electroanalytical methods based on chronoamperometry, cyclic voltammetry and fast Fourier transform electrochemical impedance spectroscopy (FFT-EIS) were adapted for the determination of cyanide ion concentration in the range between 2 mmol l−1 and 1 mol l−1. The widest range of linearly detectable concentration of cyanide ions was obtained by cyclic voltammetry-based method that allowed to quantify concentration of cyanide ions in the range from 10 mmol l−1 to 1 mol l−1 (R2 = 0.993). Chronoamperometry-based method showed the highest sensitivity to the low concentrations of cyanide enabling to detect cyanide ion in the linear range from 2 mmol l−1 to 50 mmol l−1 (R2 = 0.995). The FFT-EIS-based method exhibited linear range from 100 mmol l−1 to 700 mmol l−1 (R2 = 0.975) showing suitability of this method for the quantification of cyanide ion concentration in highly concentrated cyanide solutions. Moreover, the FFT-EIS-based method allows to carry out quantification of cyanide very fast, by registering the impedance spectrum within 0.5 s. Therefore, all three cyanide quantification methods presented in this research are convenient for the estimation of cyanide concentration in the relevant concentration ranges.