Preparation and characterization of the dopamine film electrochemically deposited on a gold template and its applications for dopamine sensing in aqueous solution

A dopamine polymer film was electrogenerated on the bare gold template from a 5 × 10⁻³ M dopamine solution in phosphate buffer at pH 7 and next subjected to overoxidation in 0.1 M sodium hydroxide solution. The overoxidized dopamine polymer film obtained shows good permeability to cationic species and was used for quantitative determination of dopamine. A linear relationship between dopamine concentration and current response was obtained in the range of 1 × 10⁻⁶ M to 6 × 10⁻⁴ M with the detection limit 2 × 10⁻⁷ M. The results have shown that using the overoxidized dopamine film it is possible to perform electrochemical analysis of dopamine without interference of ascorbic and uric acids, which is the major limitation in dopamine determination. The modified electrode shows good selectivity, sensitivity, reproducibility and high stability.