Electrochemical determination of ajmalicine using glassy carbon electrode modified with gold nanoparticles

A simple, sensitive, and economically viable electrochemical method for the determination of ajmalicine was developed. The procedure involves a glassy carbon electrode modified with gold nanoparticles (GCE/AuNPs). In the work presented here gold nanoparticles were attached to the glassy carbon electrode by adsorption. Cyclic voltammetry was used for the first time for the electrochemical characterization of ajmalicine and differential pulse voltammetry for its quantitative determination. Britton-Robinson buffer solution in a range of pH values served as supporting electrolyte. The experimental conditions were optimized and it was found that ajmalicine provided a well-defined oxidation peak at a potential of +0.8 V vs. Ag/AgCl (3 M KCl). The method for the determination of ajmalicine showed a dynamic range for concentrations from 5 to 50 A mu M with a detection limit of 1.7 A mu M, good repeatability (RSD of 1.4 %) and reproducibility (RSD of 2.5 %). The effect of possible interferents (yohimbine, reserpine) appeared to be negligible. The proposed procedure was successfully applied for the first time to the determination of ajmalicine in commercially available oral solutions for medical applications with results in good agreement with the declared content of ajmalicine. [GRAPHICS]