Electrochemical determination of levodopa in the presence of ascorbic acid by polyglycine/ZnO nanoparticles/multi-walled carbon nanotubes-modified carbon paste electrode

This work report on electrodeposition of polyglycine microparticles onto zinc oxide (ZnO) nanoparticles/multi-walled carbon nanotube-modified carbon paste electrode surface in order to construction new levodopa (l-dopa) electrochemical sensor. The prepared electrode used for sensitive and selective determination of l-dopa in the presence of ascorbic acid. The electrochemical response of l-dopa on this modified electrode was studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The effect of various experimental parameters including pH and scan rate on the voltammetric response of l-dopa was investigated. The results show that the process of oxidation of this compound is adsorption controlled. At the optimum conditions, the concentration of l-dopa was determined by differential pulse voltammetry, and a dynamic linear range of 5.0-500.0 mu mol L-1 and detection limit of 0.08 mu mol L-1 were obtained. The results of pharmaceutical and human urine samples' voltammetric analysis showed that using the proposed method, a precise and sensitive electrochemical determination of l-dopa is feasible.