Simultaneous voltammetric determination of ascorbic acid and dopamine at the surface of electrodes modified with self-assembled gold nanoparticle films

Gold nanoparticles (GNs) could be efficiently immobilized on binary mixed self-assembled monolayers (SAMs) on a gold surface composed of 1,6-hexanedithiol and 1-octanethiol (nano-Au/SAMs gold electrode). This GN chemically modified electrode was used for electrochemical determination of ascorbic acid (AA) and dopamine (DA) in aqueous media. The result showed that the GN-modified electrode could clearly resolve the oxidation peaks of AA and DA, with a peak-to-peak separation (a dagger E (p)) of 110 mV enabling determination of AA and DA in the presence of each other. The linear analytical curves were obtained in the ranges of 0.3-1.4 mM for AA and 0.2-1.2 mM for DA concentrations using differential pulse voltammetry. The detection limits (3 sigma) were 9.0 x 10(-5) M for AA and 9.0 x 10(-5) M for DA.