Cyclic Voltammetric Determination of Ascorbic Acid with Quercetin Modified Carbon Paste Electrode

Quercetin modified carbon paste electrode was prepared. As shown by the result of CV study on the electrochemical behavior of ascorbic acid(AA)at this modified electrode, a sensitive quasi-reversible oxidation peak was observed at +0.39 V (vs.SCE) in phosphate buffer medium of pH 4.5. It was found that the charge transfer process on the modified electrode was controlled by adsorption. Linear relationship between values of oxidation peak current and concentration of AA was kept in the range of 5.0×10-6-5.0×10-4mol·L-1, with detection limit (3S/N) of 2.5×10-6mol·L-1. The modified electrode was used in the determination of AA in vitamin C tablets, giving values of recovery in the range of 96%-104%.