Some properties of sodium dodecyl sulfate functionalized multiwalled carbon nanotubes electrode and its application on detection of dopamine in the presence of ascorbic acid

A sodium dodecyl sulfate (SDS) functionalized multiwalled carbon nanotubes (MWNTs) electrode (SDS/MWNTs) was successfully constructed in this study. The electrochemical property of the SDS/MWNTs electrode has been characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Nyquist plots suggest that the immersion time of SDS affects the resistances of the MWNTs electrodes. The thickness of adsorbed SDS on MWNTs surface is estimated to be 1.23 nm, which is close to the value of SDS monolayer. CV results demonstrate a 5-fold enhanced response for dopamine (DA) at the SDS/MWNTs electrode compared to the bare MWNTs one. DPV results illustrate that DA can be selectively determined in the presence of high concentration ascorbic acid (AA) with a linear range from 20 mu M to 0.20 mM and a sensitivity of 0.024 mu A mu M-1 at the SDS/MWNTs electrode.