Nanostructure Electrochemical Sensor for Voltammetric Determination of Vitamin C in the Presence of Vitamin B: Application to Real Sample Analysis

Abstract

A carbon paste electrode modified by using ZnO/CuO nanosheets, ionic liquids (N-hexyl-3methylimidazolium hexafluoro phosphate) and 2-(ferrocenylethynyl)fluoren-9-one was fabricated and used for electrocatalytic oxidation of vitamin C. It has been found that, the oxidation of vitamin C at the surface of such an electrode occurs at a potential about 190 mV less positive compared to an unmodified carbon paste electrode. The oxidation peak currents show a linear dependence on the vitamin C concentrations in the range of 4.0× 10 -8 M– 1.0×10 -3 M with a detection limit of 2.0×10 -8 M. The diffusion coefficient (D/cm 2 s −1 =5.38×10 −6 ), electron transfer coefficient, (α=0.28) and the heterogeneous rate constant, (k/M -1 s -1 =2.3×10 3 ) for vitamin C were determined using electrochemical approaches. The modified electrode exhibits good resolution between the voltammetric peaks of vitamin C and vitamin B 6 that makes it suitable for the detection of vitamin C in the presence of vitamin B 6 in real samples.