Simultaneous Determination of Dopamine, Ascorbic Acid and Uric Acid at Poly (cinnamic acid) Modified Carbon Paste Electrode: a Voltammetric Investigation

A Polymer film of cinnamic acid was formed on the surface of a bare carbon paste electrode (BCPE) by electropolymerisation of cinnamic acid in pH 7 Phosphate buffer solution (PBS) by using cyclic voltammetry (CV). This lead to the formation of polycinnamic acid modified carbon paste electrode (PCA/CPE). CV was used to study the electrochemical properties of the polymer film on the PCA/CPE. The modified electrode was used for the simultaneous electrochemical detection of dopamine (DA), ascorbic acid (AA) and uric acid (UA). The PCA/CPE showed a very good electrocatalytic activity for the oxidation of DA, AA and UA and exhibited an excellent ability to separate DA from AA by means of CV. The anodic peak potentials of DA and AA were separated by 0.259 V in pH 7 PBS containing 0.1 mM of DA and 2 mM of AA at the scan rate of 50 m V/S. The detection limit (LOD) and quantification limit (LOQ) of the present technique were found to be 3.52×10-6 M and 1.16×10-5 M respectively for DA. Compared to BCPE, the PCA/CPE exhibited the enhanced peak currents for DA, AA and UA. Also, the PCA/CPE showed good recoveries for DA in real sample analysis i.e. for both pharmaceutical formulations and blood serum. Hence, this modified electrode can be used for the selective determination of DA in the presence of higher concentrations of AA and UA in pharmaceuticals and medicine without any problem with greater sensitivity, selectivity and reproducibility.