Voltammetric determination of copper with proton pump inhibitor drug omeprazole

The electrochemical behavior of copper(II)-omeprazole complex was studied by differential pulse and cyclic voltammetry at a hanging mercury drop electrode. A well-defined voltammetric peak was obtained at −0.6 V (vs. Ag/AgCl sat’d KCl) in phosphate buffer (pH 7). The experimental results show that the reduction of the copper(II)-omeprazole complex is irreversible. The stoichiometry and stability constant of the Cu(II)-omeprazole complex were evaluated using differential pulse cathodic adsorptive stripping voltammetry and found to be 1 : 2 and 1.39 × 1011 M−1. The limits of detection and quantitation were found to be 3 × 10−9 and 1 × 10−8 M, respectively. The proposed procedure was successfully applied for the determination of trace level of copper in bottled natural drinking water samples.