A New Negative Charged Self-Assembled Monolayer for Selective Electroanalytical Determination of Dopamine in the Presence of Ascorbic Acid

Voltammetric behavior of dopamine and ascorbic acid on a gold electrode modified with the self-assembled monolayer of 2-mercaptoethanesulfunate has been investigated. This negatively charged layer could act as a discriminating layer against ascorbic acid and dopamine based on the electrostatic interactions. Thus modified electrode enabled selective determination of dopamine in an excess of ascorbic acid. The oxidation peak current increases linearly with the concentration of dopamine in the range of 1.0 × 10 −5 to 3.5 × 1