Selective Determination of Dopamine in the Presence of Ascorbic Acid Using a Poly (Nicotinic Acid) Modified Carbon Paste Electrode

A carbon paste electrode (CPE) modified with poly (nicotinic acid) was used for the sensitive and selective voltammetric determination of dopamine (DA). The electrochemical response characteristics of the modified electrode toward DA, ascorbic acid (AA) were investigated by cyclic voltammetry (CV). The results show an efficient catalytic activity of the electrode for the electro-oxidation of DA, which leads to an improvement to the reversibility of the electrode response. The effect of pH and potential sweep rate on the mechanism of the electrode process was investigated. The modified electrode exhibits an efficient electron mediating behavior along with well-separated oxidation peaks for AA and DA. Under the optimum pH of 7.0 in 0.2 M phosphate buffer solution (PBS), the CV anodic peak current showed a linear relation vs. DA correlation coefficients. High sensitivity and selectivity, high reproducibility, along with ease of preparation and regeneration of the electrode surface by simple polishing make this method suitable for the determination of DA and AA in pharmaceutical and clinical preparations.