Selective electrochemical detection of dopamine in the presence of uric acid and ascorbic acid based on a composite film modified electrode

An electrochemical sensor was built by the layer-by-layer self-assembly method for selective and sensitive determination of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA), based on vanadium-substituted polyoxometalates, copper oxide and chitosan–palladium. This sensor was characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry, electrochemical impedance spectroscopy and current–time were employed to investigate the electrochemical and sensing properties. The results indicated the proposed sensor had good electrocatalytic activity towards the oxidation of dopamine and exhibited a low detection limit of 0.045 μM (S/N = 3), a wide linear range of 0.25–217 μM and fast response (<2 s). In addition, the sensor exhibited excellent reproducibility, long-term stability and good anti-interference ability towards common coexistent compounds. Finally, this sensor was employed to detect DA in real blood serum samples and the recovery is acceptable within the allowed error range.