Abstract:
Cyclic voltammetry (CV) and square wave voltammetry (SWV) were used for characterizing and determining Vitamin C concentration in fresh Garlic collected in some selected kebeles of North Gondar administrative zone, Ethiopia. In this study, Ascorbic acid (AA) content in Garlic was determined by SWV technique. The effect of Ascorbic acid concentration on the oxidation response of CPE, pH of phosphate buffer solution and scan rate on the response characteristics of the electrode were investigated by CV. It was found that the anodic peak current of AA is directly related to the concentration and scan rate, whereas during pH optimization, the anodic peak current was increased with the pH value ranges 1 – 3. However, the peak current was found to decrease after pH 3. Hence, pH 3 is chosen as the optimum value for this work. On the other hand, the anodic peak potential is shifted to less positive as a function of pH values used. A calibration curve was obtained by the square wave voltammetry at CPE after square wave frequency, step potential, and square wave amplitude were optimized. The optimized parameters chosen for the whole work were a wave frequency of 25 HZ, a step potential of 8 mV, and wave amplitude of 35 mV, respectively. The Vitamin C content determined in this work using SWV was 22.8 mg/100 g and 19.45 mg/100 g of Debark and Gondar Garlic respectively. From the results obtained, the ascorbic acid content of Debark Garlic was higher than Gondar Garlic. The recoveries ranging between 99.99-99.98% were achieved indicating the method for the determination of vitamin C in real samples was more valid.