A glassy carbon electrode (GCE) has been modified by electrochemical oxidation in mild acidic media
(0.1 mol l−1 H2SO4) and could be applied for individual and simultaneous determination of ascorbic acid
(AA), dopamine (DA) and uric acid (UA). Oxidized GCE shows a single redox couple (E0 =−2.5mV) which
is based on the formation functional groups during the electrochemical pretreatment process. Proposed
GCE successfully decreases the over potentials for the oxidation process of these species (AA, DA and
UA) comparing with bare GCE. The oxidized GCE has its own simplicity, stability, high sensitivity and
possesses the potential for simultaneous determination of AA, DA and UA.