Electroanalysis of Dopamine at RuO2 Modified Vertically Aligned Carbon Nanotube Electrode

Electrochemical behavior of dopamine at the RuO₂‐modified vertically aligned carbon nanotubes electrode was investigated by cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The RuO₂‐modified carbon nanotube electrode showed higher electrocatalytic activity towards the oxidation of dopamine than the MWNTs electrode in 0.10 M phosphate buffer solution. At an applied potential of +0.4 V, the RuO₂/MWNTs electrode exhibited a wide detection range up to 3.6×10^?3 M with detection limit of 6.0×10^?8 M (signal/noise=3) for dopamine determination. Meanwhile, the optimized sensor for dopamine displayed a sensitivity of 83.8 μA mM^?1 and response time of 5 s with addition of 0.20 mM dopamine. In addition, DPV experiment revealed that interfering species such as ascorbic acid and uric acid could be effectively avoided. The RuO₂/MWNTs electrode presents stable, highly sensitive, favorable selectivity and fast amperometric response of dopamine.