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 mu M (S/N = 3), a wide linear range of 0.25-217 mu M 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.