Sensitive electrochemical sensor for determination of methyldopa based on polypyrrole/carbon nanoparticle composite thin film made by in situ electropolymerization

摘要

A 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 pH3.0 under a diffusion controlled process. A wide linear dynamic range (0.2-50μM) with a detection limit of 60nM 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.