Evaluation of Antioxidant Activity of Tea Beverage by Ag(Ⅲ)-Luminol Flow Injection Chemiluminescence Method

Using 8 kinds of tea polyphenols commonly found in tea as research objects, the correlation between trivalent silver complexesAg(Ⅲ)-luminol flow injection chemiluminescence method and DPPH radical scavenging method, catechol-carbonate-luminol chemiluminescence method, luminol-hydrogen peroxide chemiluminescence method was studied. The antioxidant activity of four tea beverages was evaluated by Ag(Ⅲ)-luminol flow injection chemiluminescence method. The operating parameters of the instrument were set as follows:pure water was used as carrier solution, the speed of peristaltic pump was set to 25 r·min^-1, and the regative high voltage of photoelectric multiplier tube was 600 V. The results showed that the difference of chemiluminescence intensity obtained by Ag(Ⅲ)-luminol flow injection chemiluminescence method had a good correlation with the IC₅₀ (the respective concentration of the antioxidant with the free radical scavenging rate of 50%) obtained by DPPH radical scavenging method, with the correlation coefficient of 0.9490. Ag(Ⅲ)-luminol flow injection chemiluminescence method was used to evaluate the antioxidant properties of four tea beverages sold on the market, giving results consistent with those obtained by DPPH radical scavenging method, and the correlation coefficient was 0.9665.