Sensitive Electrochemical Sensor for Determination of Methyldopa Based on Polypyrrole/Carbon Nanoparticle Composite Thin Film Made by In Situ Electropolymerization

Abstract

AbstractA composite surface coating is prepared by electropolymerization of a mixture of pyrrole and carbon nanoparticles onto a glassy carbon electrode (GCE). The microscopic structure and morphology of the composite film is characterized by scanning electron microscopy. The modified electrode offers a considerable improvement in voltammetric sensitivity toward methyldopa (m‐dopa), compared to the bare and polypyrrole‐coated GCEs. A significantly enhanced anodic peak current together with a remarkable increase in sharpness of the cyclic voltammetric (CV) signals are observed for the detection of m‐dopa. The effect of experimental parameters, such as scan rate and pH, are investigated by monitoring CV responses toward m‐dopa. It is found that a maximum current response can be obtained at pH 3.0 under a diffusion controlled process. A wide linear dynamic range (0.2–50 µM) with a detection limit of 60 nM is achieved for m‐dopa. The excellent response characteristics, e.g., high sensitivity, very good repeatability and reproducibility, and low detection limit, have made the prepared sensor suitable for the analysis of m‐dopa in pharmaceutical and clinical preparations.