Electrocatalytic oxidation of 3,4-dihydroxyphenylacetic acid at a glassy carbon electrode modified with single-wall carbon nanotubes

Abstract

Abstract The voltammetric behavior of 3,4-dihydroxyphenylacetic acid (DOPAC) was studied at a glassy carbon (GC) electrode modified with single-wall carbon nanotubes (SWNTs). In 0.1 M HAc–NaAc buffer solution (pH 4.4), the SWNT-modified electrode shows high electrocatalytic activity toward oxidation of DOPAC. One well-defined redox couple is obtained. The peak current increases linearly with the concentration of DOPAC in the range of 1.0×10 −6 –1.2×10 −4 M. The detection limit is 4.0×10 −7 M. The results indicate that DOPAC undergoes a two-electron oxidation to o -quinone followed by a dimerization reaction. Rate constant for this dimerization reaction was calculated to be 2.10×10 3 dm 3 mol −1 s −1 . The SWNT was characterized with scanning electron microscope (SEM). This SWNT-modified electrode can also separate the electrochemical responses of DOPAC and 5-hydroxytryptamine (5HT).