Electrochemical determination of bismuth with use of a Bi(III)-cupferron complexation system and elimination of interferences connected with the presence of organic substances in natural samples

A sensitive and selective method for the determination of bismuth based on adsorptive stripping voltammetry using cupferron as a complexing agent is presented. The effect of various parameters such as concentration of cupferron, the pH of the supporting electrolyte, the accumulation potential and time on the sensitivity was studied. The optimal analytical conditions were found to be cupferron concentration of 1 × 10−4 mol L−1, an acetate buffer of pH = 3, accumulation potential of 50 mV. The calibration graph is linear from 2 × 10−9 to 2 × 10−7 mol L−1 for accumulation time of 30 s. The influence of interfering substances such as surfactants and humic substances present in the matrices of natural samples on the Bi(III) signal was examined. Additionally, in this work a procedure for removing these disturbing organic substances due to their adsorption on Amberlite XAD-7 resin was successfully evaluated. The procedure was applied to determine bismuth in natural water samples.