Electroless Deposition of bis(4′-(4-Pyridyl)-2,2′: 6′, 2-terpyridine)iron(II) Thiocyanate Complex onto Carbon Nanotubes Modified Glassy Carbon Electrode: Application to Simultaneous Determination of Ascorbic Acid, Dopamine and Uric Acid

A glassy carbon (GC) electrode modified by multi-walled carbon nanotubes (MWNTs) and bis(pyterpy) iron(II) thiocyanate complex (pyterpy = 4'-(4-pyridyl)-2,2': 6', 2''-terpyridine) was investigated by voltammetric methods in acetate buffer solution (pH 5). Performances of the iron(II)-complex/MWNTs modified electrode were evaluated with differential pulse voltammetry and scanning electron microscopy (SEM). The modified glassy carbon electrode shows an excellent electrochemical response for ascorbic acid (AA), dopamine (DA) and uric acid (UA). The differential pulse voltammetry oxidation peaks for AA and DA, DA and UA, AA and UA are separated by 210, 136 and 346 mV, respectively. This separation permits the simultaneous determination of AA, DA and UA. The anodic peak currents of AA, DA and UA increase linearly with concentration in the range of 1.10x10(-5)-1.50x10(-3) mol L(-1), 9.0x10(-7)-1.20x10(-3) mol L(-1) and 2.00x10(-6)-1.50x10(-3) mol L(-1), respectively, with a correlation coefficient (r) always higher than 0.998. In addition, the modified electrode also shows good sensitivity and stability. Satisfactory results were achieved for the determination of AA in vitamin C tablets, DA in dopamine injection solution and UA in human blood serum samples.