Oxidation and reduction of omeprazole on boron-doped diamond electrode: Mechanistic, kinetic and sensing performance studies

Voltammetric behavior of omeprazole on chemically unmodified boron-doped diamond electrode was investigated. Omeprazole is possible to oxidize and reduce in various supporting electrolytes. Both processes are strongly dependent on pH value of the solution. Well defined oxidation and reduction signal of omeprazole was observed at high and low pH values of supporting electrolyte. Kinetics of charge transfer in the pH range from 3 to 10 in various supporting electrolytes was studied and characterized by the estimation of formal potentials (+1.07 to +0.89 V for oxidation and -0.95 to -1.18 V for omeprazole reduction), charge transfer coefficients (0.52-0.33 for oxidation and 0.19-0.17 for reduction) together with standard heterogeneous rate constants. The analytical performance was studied with linear sweep voltammetry, square-wave voltammetry and differential pulse voltammetry. The lowest detection limit of 9.1 x 10(-8) mol L-1 for oxidation of omeprazole was achieved by SWV technique. The proposed simple, sensitive and cheap method was validated and applied for pharmaceutical formulations and human urine as real samples. (C) 2016 Elsevier B.V. All rights reserved.