Low potential determination of dopamine in the presence of ascorbic acid using phenothiazine dye–functionalized graphite oxide–modified electrode

Azure A, a phenothiazine dye was functionalized at graphite oxide through EDC/NHS coupling chemistry. The Azure A–functionalized graphite oxide (AzA-GO) was modified at paraffin impregnated graphite electrode (PIGE) and was used in the precise electrochemical determination of dopamine (DA) in the presence of ascorbic acid (AA). The functionalized AzA-GO was characterized using FTIR, UV–visible spectroscopy, and scanning electron microscopy (SEM). The AzA-GO–modified electrode was characterized by cyclic voltammetry (CV). The electrocatalytic oxidation of DA was found to happen at a low oxidation potential of 0.14 V by the modified electrode. The determination of DA was linear in the concentration range of 8.6 × 10−6 to 9.09 × 10−3 M with the detection limit of 7.2 × 10−7 M. The selective determination of DA in the presence of 100 times higher concentration of AA was achieved by differential pulse voltammetry (DPV). The modified electrode offered a simple, sensitive, and selective determination of low levels of DA at the lower oxidation potential. The proposed sensor has the advantage of easy fabrication, low cost, good sensitivity, selectivity, reproducibility, and stability.