Graphene nano sheet-fabricated electrochemical sensor for the determination of dopamine in the presence of ascorbic acid using cetyltrimethylammonium bromide as the discriminating agent

A biosensor was fabricated using graphene nano-sheets (GNSs) as the component for signal amplification and cetyltrimethylammonium bromide (CTAB) as the discriminating agent with the aim of achieving the selective and sensitive determination of dopamine (DA) in the presence of ascorbic acid (AA). The electrochemical behavior of DA was studied by cyclic voltammetry and differential pulse voltammetry (DPV). The results showed that DA and AA in coexisting solutions can be simultaneously oxidized in an electrochemical manner at significantly different potentials in the presence of CTAB. Therefore, DA can be selectively determined from a mixed solution even in the presence of interferents. The DPV current showed a linear dependence on DA concentrations ranging from 4 × 10−6 M to 5.2 × 10−5 M with a detection limit of 6.0 × 10−7 M. The proposed method was used to detect DA in real human blood serum using the standard addition method with satisfactory results. The reliability of the method was also examined with the fluorescence spectroscopy. The reaction mechanism was explored and a defect in micelles was highlighted to explain the high sensitivity and selectivity of the method.