Electrochemical behavior of poly (naphthol green B)-film modified carbon paste electrode and its application for the determination of dopamine and uric acid

A polymerized film of naphthol green B was prepared on the surface of a carbon paste electrode in Britton–Robinson (B−R) buffer solution by electropolymerization technique. Electrochemical investigation of the resulting film was studied by cyclic voltammetric method. Several factors affecting the electrocatalytic activity of the hybrid material such as, effect of pH, scan rate and concentration were studied. The results suggested that the modified electrode exhibited enhanced sensitivity and selectivity towards the oxidation of dopamine (DA) and uric acid (UA). Well defined and separated oxidation peaks were observed by cyclic voltammetry and differential pulse voltammetry. Linear calibration plots for the oxidation of DA and UA were obtained in the range of 5 × 10−6 M to 2.7 × 10−4 M for DA and 12.5 × 10−6 M to 7.5 × 10−4 for UA, with a correlation co-efficient of 0.991 and 0.995, respectively. Detection limits of DA and UA were found to be 0.25 ± 0.05 μM and 5 ± 0.04 μM, respectively. The analytical performance of this sensor has been evaluated for detection of DA and UA in real samples.