ELECTROCHEMICAL DETECTION OF VITAMIN C IN REAL SAMPLES

Electrochemical properties of vitamin C (also known as L-ascorbic acid) have been studied by cyclic and differential pulse voltammetry in the model systems in order to develop simple and suitable method for vitamin C detection in real samples. The results indicated that vitamin C oxidation is a quasi-reversible and diffusion-controlled process, as well that the oxidation product of ascorbic acid, dehydroascorbic acid is adsorbed on the glassy carbon electrode surface. Calibration curve was constructed and the linear response was obtained in a concentration range from 0.0025 mol dm-3 to 1.0 mol dm-3. Vitamin C was successfully determined in real samples (fruit juices and food supplement) with cyclic voltammetry within concentration range from 0.034 mol dm-3 to 0.340 mol dm-3. In addition, antioxidant activity of vitamin C in real samples was determined using DPPH assay with a good linear correlation obtained between the cyclic voltammetry results and the results evaluated by DPPH assay of the samples