Electrochemistry Of The Quercetin Modified Electrode

The quercetin modified electrodes were prepared by entrapped in carrageenan hydrogel and absorbed using cyclic voltammetry. Quercetin indicated a quasi-reversible cyclic voltammetric behavior in the range of pH 1.5-6.0. Both the oxidative and reductive peak currents increase with the decrease of pH. The potentials shift positively and have a linear relationship with the decrease of pH, demonstrating the redox reaction companied the proton transfer. The redox peaks were not observed clearly when the pH is more than 8.0. Another peak appears beside the main redox peak when in higher acidic solution. The peak current decreases with the increase of the potential scan. The quercetin-carrageenan modified electrode is more stable and the redox reaction is more reversible than the absorbed one.Ascorbic acid can be oxidized catalytically by quercetin modified electrodes. The oxidation peak of quercetin increase gradually, while the reduction peak decrease gradually when quercetin added ascorbic acid into pH 4.0 buffer solution. The current is good linear relationship with the concentration of ascorbic acid in the range of 3.1×10^-5mol·L^-1～2.0×10^-2mol·L^-1 The detection limit is 1.5×10^-5mol·L^-1. Quercetin is effective mediator to oxidize ascorbic acid and this method can be used for the quantitative detection of ascorbic acid.Quercetin is also a good mediator to oxidize Nicotinamide Adenine Dinucleotide (NADH). The oxidation peak of quercetin increase gradually, while the reduction peak decrease gradually when quercetin added NADH into pH 4.0 buffer solution. The current is good linear relationship with the concentration of NADH in the range of 2.6×10^-4mol·L^-1～4.0×10^-3mol·L^-1. The detection limit is 2.1×10^-5mol o L^-1. Quercetin can decrease the over-potential of catalytically oxidizing NADH which can be used as mediator to construct biosensor based on NADH dehydrogenase.