Direct Determination of Ascorbic Acid in Fruits and Vegetables by Positive Scan Polarization Reverse Catalytic Voltammetry

The positive scan polarization reverse catalytic voltammetry was used for direct detection of ascorbic acid in fruit and vegetable samples. An ascorbic acid sensor was fabricated based on CuxO nanoparticles protected by the graphene oxide (GO) layer. The common copper electrode was first electrooxidized in strong alkaline solution to generate CuxO nanoparticles on the electrode surface, then GO was electrodeposited to form a protective layer covered on the surface of CuxO nanoparticles. The resulting sensor exhibited excellent electrocatalytic activity toward oxidation of ascorbic acid. There was a wide linear range between the difference value peak current of the sensor and the ascorbic acid concentration from 1.25 x 10(-7) M to 1.60 x 10(-5) M, with a detection limit of 5.90 X 10(-8) M (S/N = 3). The results demonstrated that the proposed method possessed excellent detection capability, including fast response, high reproducibility and stability.