Electrochemical detection of dopamine in the presence of epinephrine, uric acid and ascorbic acid using a graphene-modified electrode

A sensitive and selective electrochemical method for the determination of dopamine (DA) in the presence of epinephrine (EP), uric acid (UA) and ascorbic acid (AA) was developed using a graphene-modified electrode. The electrochemical behaviour of DA at the modified electrode was studied by cyclic voltammetry. The results showed that the modified electrode exhibited excellent electrocatalytic activity towards the electrochemical oxidation of DA. When the reduction peak current of DA, in pH 7.0 phosphate buffer solution, was measured at a potential range of -0.1 to 0.6 V, no interference occurred from EP, UA and AA. The reduction peak current was linearly proportional to DA concentration from 2.50 x 10(-6) to 1.00 x 10(-4) mol L-1. The values of correlation coefficient and limit of detection for DA were 0.9984 and 5.00 x 10(-7) mol L-1, respectively. The modified electrode shows excellent sensitivity, selectivity and stability for the voltammetric determination of DA in the presence of EP, UA and AA and was satisfactorily used for the determination of DA in pharmaceutical and biological samples.