Electrochemically selective determination of dopamine in the presence of ascorbic and uric acids on the surface of the modified Nafion/single wall carbon nanotube/poly(3-methylthiophene) glassy carbon electrodes

A voltammetric method based on a combination of incorporated Nafion, single-walled carbon nanotubes and poly(3-methylthiophene) film-modified glassy carbon electrode (NF/SWCNT/PMT/GCE) has been successfully developed for selective determination of dopamine (DA) in the ternary mixture of dopamine, ascorbic acid (AA) and uric acid (UA) in 0.1 M phosphate buffer solution (PBS) pH 4. It was shown that to detect DA from binary DA–AA mixture, the use of NF/PMT/GCE was sufficient, but to detect DA from ternary DA–AA–UA mixture NF/SWCNT/PMT/GCE was required. The later modified electrode exhibits superior electrocatalytic activity towards AA, DA and UA thanks to synergic effect of NF/SWCNT (combining unique properties of SWCNT such as high specific surface area, electrocatalytic and adsorptive properties, with the cation selectivity of NF). On the surface of NF/SWCNT/PMT/GCE AA, DA, UA were oxidized respectively at distinguishable potentials of 0.15, 0.37 and 0.53 V (vs. Ag/AgCl), to form well-defined and sharp peaks, making possible simultaneous determination of each compound. Also, it has several advantages, such as simple preparation method, high sensitivity, low detection limit and excellent reproducibility. Thus, the proposed NF/SWCNT/PMT/GCE could be advantageously employed for the determination of DA in real pharmaceutical formulations.