Electrooxidation of dextromethorphan on a carbon nanotube-carbon microparticle-ionic liquid composite: applied to determination in pharmaceutical forms

The electrooxidation of dextromethorphan on a composite constructed with carbon nanotube-ionic liquid-carbon microparticles was investigated by cyclic voltammetry in a 100 mM phosphate buffer solution, pH 7.40. In the voltammograms, an irreversible diffusion-controlled anodic peak appeared. The diffusion coefficient of dextromethorphan, the electron-transfer coefficient, and the standard rate constant of the electrooxidation process were found to be 3.45 x 10(-6) cm(2) s(-1), 0.65, and 1.67 x 10(-3) cm s(-1), respectively. A sensitive and timesaving determination procedure was developed for the analysis of dextromethorphan, and the corresponding analytical parameters were reported. Using this method, dextromethorphan was determined with an LOD and LOQ of 8.81 and 29.36 mu M in a linear range of 2.5 x 10(-4) to 3.3 x 10(-3) M, respectively. The proposed amperometric method was successfully applied to the analysis of commercial pharmaceutical products (syrup and oral drop), and the results were in good agreement with the declared values.