Simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid using poly (tyrosine)/functionalized multi-walled carbon nanotubes composite film modified electrode

Abstract

A novel poly (tyrosine)/carboxyl functionalized multi-walled carbon nanotubes composite film modified electrode has been fabricated and used as electrochemical sensor for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The prepared electrode not only separated the cyclic voltammetric signals of AA, DA and UA with oxidation potential difference of 160 and 150mV between AA–DA and DA–UA, respectively but also showed higher oxidation current for these molecules in pH 7.4 phosphate buffer solution. Because it exhibited excellent selectivity towards the oxidation of AA, DA and UA, the modified electrode was used for simultaneous voltammetric measurement of the three analytes by differential pulse voltammetry. Under the optimum conditions, the detection limits for AA, DA and UA were 2.0μmolL−1, 0.02μmolL−1 and 0.30μmolL−1, respectively (S/N of 3). The method has good selectivity and sensitivity and was successfully applied to the simultaneous determination of AA, DA and UA in spiked human serum.