Application of carbon-paste electrode modified with iron phthalocyanine for voltammetric determination of epinephrine in the presence of ascorbic acid and uric acid

A carbon-paste electrode (CPE) modified with iron(II) phthalocyanine was used for the sensitive voltammetric determination of epinephrine (EN). The electrochemical response characteristics of the modified electrode toward EN, ascorbic acid (AA) and uric acid (UA) were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results Show an efficient catalytic activity of the electrode for the electro-oxidation of EN, which leads to improvement of reversibility of the electrode response and lowering its overpotential by more than 100 mV. 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 together with well-separated oxidation peaks for EN, AA and UA. Under the optimum pH of 4.0 in 0.1 M acetate buffer solution, the DPV anodic peak current showed a linear relation versus EN concentration in the range of 1-300 mu M, with a correlation coefficient of 0.998 and a detection limit of 0.5 mu M. High sensitivity and selectivity, sub-micromolar detection limit, high reproducibility, together with ease of preparation and regeneration of the electrode surface by simple polishing, make the electrode very suitable for the determination of EN in pharmaceutical and clinical preparations. (C) 2009 Elsevier B.V. All rights reserved.