Use of SWCNT′s Nafion Composite Film Modified Glassy Carbon Electrode in Differential Pulse Voltammetric Determination of Dopamine

To prepare single-wall carbon nanotubes, nafion composite film modified glassy carbon electrode (designated abbreviately as SWCNT′s/Nafion/GCE), a dispersion of SWCNT′s in 5% (w%) Nafion solution was added dropwise onto the surface of GCE, and dried by infrared radiation. Electrochemical behavior of the modified electrode was studied by cyclic voltammetry. It was found that a pair of redox peaks given by dopamine was observed at the SWCNT′s/Nafion/GCE with values of Epa of 0.408 V (vs. Ag/AgCl electrode) and Epc of 0.335 V and that the magnitade of peak current was enhanced by 50 times as compared with the bare GCE. Based on these findings, a selective method for determination of dopamine by differential pulsed voltammetry was proposed. Linear relationship between values of peak current of oxidation peak and concentration of dopamine was obtained in the range within 120 μmol·L-1, with detection limit (3S/N) of 0.2 μmol·L-1. The proposed method was used in the determination of dopamine in injection samples, giving results in consistency with the labeled values. Recovery of the method was tested by standard addition method, and values of recovery found were in the range of 96.2%-101.0%.