Glassy carbon electrodes modified with graphene oxide (GO), gold nanoparticles (AuNP) and methylene blue (MB) were produced by drop casting method for ascorbic acid (AA) determination. Nafion was used as a polymeric immobilizing matrix. The GCE/GO-AuNP-MB-Nafion and GCE/GO-AuNP-Nafion electrodes were characterized by using cyclic voltammetry and electrochemical impedance spectroscopy to investigate electrocatalytic effect, stability and reproductibility. After optimization, the analytical parameters of the modified electrodes were determined by amperometry. The limit of detection for ascorbic acid at GCE/GO-AuNP-Nafion modified electrode was 2.4 µM and the linear domain from 5 to 50 µM. The electrodes showed significant electrocatalytic effect with good stability and reproductibility
