Abstract:

On the basis of electropolymerization of dopamine(DA) at multiwalled carbon nanotubes(MWCNTs) modified glassy carbon(GC) electrodes, polydopamine(PDA)/MWCNTs/GC electrodes were prepared and characterized by electrochemical impedance spectroscopy(EIS) and cyclic voltammetry(CV). The electrode exhibited well-defined electrochemical behavior of DA in pH=7.4 phosphate buffer, producing higher oxidation currents than those on a bare GC electrode, and the direct electrochemical responses of 2.0 mmol/L ascorbic acid(AA) or K4Fe(CN)6 were inhibited, demonstrating the nano-enhancement effect of MWCNTs and the anti-anion electroanalysis selectivity due to use of the PDA film with the selective cation-permeability nature. DA electroanalysis was conducted at the electrode using CV and semi-derivative methods. The semi-derivative voltammetric peak height for DA oxidation is linear with DA concentration in the range of 0.08～1.76 μmol/L, and the linear regression equation in a phosphate buffer solution without AA or with 0.5 mmol/L coexisting AA is ipa-sd(μA/s1/2)=0.107+0.405c(μmol/L)(r2=0.986) or ipa-sd(μA/s1/2)=0.628+0.649c(μmol/L)(r2=0.992), both with detection limits of 8.0×10-8 mol/L(S/N=3). This method was used for rapid determination of DA in a DA hydrochloride injection sample with satisfactory results.

Key words: PDA/MWCNTs/GC electrode, electroanalysis, interference inhibition, DA electroanalysis.