A chemically modified electrode is constructed based on a multi-walled carbon nano-tubes (MWNTs) and nickel hydroxide nano-particles (NHNPs) composite modified-glassy carbon electrode (MWNTs/NHNPs/GCE). It is demonstrated that this sensor can be used for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The measurements were carried out by the application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods. Application of the DPV method demonstrated that in phosphate buffer (pH = 6) there was a linear relationship between the oxidation peak current and the concentration of AA over the range of 7–4500 μmol L–1. For DA the linear relationship was in the range of 2–625 μmol L–1. A similar linear relationship between oxidation peak current and concentration was observed for UA over the range of 0.8–470 μmol L–1. Under optimal conditions the modified electrode exhibited high sensitivity, selectivity and stability for AA, DA and UA determination, making it a suitable sensor for the simultaneous submicromolar detection of AA, DA and UA in solutions. The experimental results suggest that the hybrid film modified electrode combining the advantages of NHNPs and carbon nanotubes which accelerates the electron transfer reaction of AA, DA and UA on the electrode surface. The analytical performance of this sensor has been evaluated for detection of AA, DA and UA in human serum and human urine with satisfactory results.
