ABSTRACT
An economic and facilely prepared dopamine ( DA) sensor have been successfully fabricated by the electrodeposition of copper on single-walled carbon nanotubes ( SWNTs )/Nafion-modified glassy carbon electrode. The morphology of the material was observed by scanning electron microscopy ( SEM) and element composition of the material was investigated by energy dispersive X-ray spectroscopy ( EDX ) . Tests with various scan rates and pH conditions indicated that an adsorption-controlled process occured in the electrochemical system. The mechanism of the electrode reaction of dopamine involved a two-electron process which was accompanied by a deprotonation step. Electrochemical parameters were calculated with the electron transfer number as 2 . 67 , the charge transfer coefficients as 0 . 6 , the apparent heterogeneous electron transfer rate constant as 1. 38 s-1 . Under the optimal conditions with differential pulse voltammetric measurement, the linear equation was Ipa(μA)=-0. 054c (μmol/L)-3. 82(R2=0. 9988), with linear range of 5-100 μmol/L and detection limit of 0 . 0135 μmol/L ( S/N=3 ) . The main advantages of sensor included facile fabrication approach, high sensitivity, good stability and high reproducibility. The sensor was applied to the detection of DA in volunteer urine by differential pulse voltammetry with favorable recoveries of 96 . 5%-100 . 4% and relative standard deviations (RSDs) of 1. 2%-2. 4%.