Development of reagentless sensing system for the determination of antioxidative activity using micro-distance between the electrodes

点击翻译按钮获取中文摘要

Antioxidative activity is an important factor in the development of high-functional food products utilizing such characteristic of foods, and measurement of the activity is significant. This study was performed aiming at development of an antioxidative activity measurement method using no enzyme or specific reagent. When a voltage of 0.33 V is applied to an electrode such as platinum in aqueous solution, O_2^- is generated on the electrode, and the generated O_2^- produces H_2O_2 by disproportional reaction. In this study, using this principle, a negative voltage was applied to the electrode to generate O_2^-, and H_2O_2 was produced by disproportional reaction. When an antioxidative substance is present, the substance captures O_2^- and decreases the production of H_2O_2 by disproportional reaction. Detection of the amount of H_2O_2 using a proximal electrode allows investigation of antioxidative activity of substances and measurement of the activity.To effectively detect H_2O_2 produced by disproportional reaction of O_2^-, a screen-printed carbon ink electrode (W1) for measurement of H_2O_2 was placed on the opposite side of the screen-printed carbon ink electrode (W2) for generation of O_2^-. For the counter and reference electrodes, screen-printed carbon ink and silver-silver chloride ink electrode were used, respectively. To generate O_2^-, -0.9 V was applied to the W2 electrode in KCl. To the W1 electrode, 1.1 V was applied to confirm the sensor response of this electrode. The distance between the electrodes was set to 240μm. O_2^--scavenging activity of catechin standard sample solutions, tea and vegetables were measured employing this system.The results for teas and vegetables correlated satisfactorily with those obtained DPPH method. These results suggest that the proposed system provides a simple and rapid method for the determination of antioxidative activity.