Sensitive and selective determination of tolterodine tartrate and its electrochemical investigation on solid carbon based electrodes

Tolterodine tartrate, a muscarinic receptor antagonist, was oxidized in various buffer media with different pH values using cyclic, differential pulse, and square wave voltammetric techniques on glassy carbon and boron-doped diamond electrodes. Two irreversible anodic peaks were obtained. The oxidation process of tolterodine tartrate was diffusion controlled depending on pH for both electrodes. A detailed oxidation mechanism was proposed and discussed. The dependences of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were investigated. A linear response between the peak current and the tolterodine tartrate concentration was obtained using differential pulse and square wave voltammetric techniques in the range of 0.4-8.0 mu M for the peak at lower potential in acetate buffer at pH 5.7 and 0.4-40.0 mu M for the peak at higher potential in 0.1 M H2SO4 on glassy carbon electrode and in the range of 0.4-40.0 mu M in Britton-Robinson buffer at pH 11.0 on boron-doped diamond electrode. Limit of detection values varied between 0.04 and 0.13 mu M for both techniques and electrodes. The repeatability, reproducibility, precision, and accuracy of the proposed methods were investigated. The recovery studies were also achieved to check selectivity, precision, and accuracy of the methods. The proposed methods were successfully applied to determine tolterodine tartrate from pharmaceutical dosage forms without any interference from inactive excipients.