Nanostructure Electrochemical Sensor for Voltammetric Determination of Vitamin C in the Presence of Vitamin B6: Application to Real Sample Analysis

Vitamins constitute a group of compounds, which are essential to human body for health, nutrition and normal growth, self maintenance and functioning of human and animal bodies[1]. Vitamin C and vitamin B6 belongs to the water-soluble vitamins [2, 3]. Since these biochemical active molecules can not be synthesized by the human body, small quantities are required in the diet. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet [4-6]. An electrochemical method has been developed and successfully applied for the simultaneous determination of vitamin C and vitamin B6 using the carbon paste electrode modified by using ZnO/CuO nanosheets, ionic liquids (Nhexyl- 3-methylimidazolium hexafluoro phosphate) and 2-(ferrocenylethynyl)fluoren-9-one. 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/cm2 s−1=5.38×10−6), electron transfer coefficient, (α=0.28) and the heterogeneous rate constant, (k/M- 1s-1=2.3×103) for vitamin C were determined using electrochemical approaches. 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 modified electrode greatly enhanced the electrooxidation reactions of vitamin C and vitamin B6, and in optimized 432 conditions well-separated voltammetric peaks for sensitive and selective determination of vitamin C and vitamin B6 appeared using the SWV technique. The proposed method could be applied to the determination of vitamin C and vitamin B6 in real samples.