Novel nanostructure-based electrochemical sensor for simultaneous determination of dopamine and acetaminophen

A carbon-paste electrode modified with a novel molybdenum (VI) complex and carbon nanotubes have been applied to the electrocatalytic oxidation of dopamine (DA) which reduced the overpotential by about 125 mV with obviously increase the current response. Due to its strong electrocatalytic activity towards DA, the modified carbon-paste electrode can resolve the overlapped voltammetric waves of DA and acetaminophen (AC) into two well-defined voltammetric peaks with peak-to-peak separation in potentials of about 230 mV. This property allows to selective determination of DA in the presence of AC. The transfer coefficient (a) for the electrocatalytic oxidation of DA and diffusion coefficient of this substance under the experimental conditions were also investigated. In phosphate buffer solution of pH 7.0, the oxidation current increased linearly with two concentration intervals of DA, one is 0.1 to 40.0 μM and, the other is 40.0 to 800.0 μM. The detection limit (3σ) obtained by DPV was 76.0 nM. The proposed method was successfully applied to the determination of DA, and AC in some commercial pharmaceutical samples.