茶叶中单宁的荧光动力学分析法研究

Study on the Kinetic Fluorimetric Determination of Tannins in Tea

本文根据在Britton-Robinson缓冲溶液中单宁对Cu(Ⅱ)催化过氧化氢氧化吡咯红Y具有活化作用,使体系荧光狡灭,建立了一个高灵敏度荧光动力学测定痕量单宁的新方法。详细研究了体系的最佳实验条件,采用固定时间法测定体系的荧光强度。该方法的线性范围为0.06～0.96mg·L^(-1),检出限为0.032mg·L^(-1)。对含量为0.32mg·L^(-1)的单宁标准溶液进行11次平行测定,其相对标准偏差为2.3％。将方法用于茶叶中单宁含量的测定,并与Folin-Ciocalteu光度法作了对照,结果满意。

A simple and highly sensitive kinetic fluorimetric method is proposed for the determination of trace tannins, based on the activation of tannins on the oxidation of pyronine Y by hydrogen peroxide catalyzed by Cu(U)ion. The effects of some experimental conditions were investigated and discussed in detail. The fixed reaction time procedure was used to determine the fluorescence intensity of the system. The calibration curve of tannin was linear in the range of 0.06-0.96 mg.L-1 and the detection limit for tannin was 0.032 mg.L-1. The relative standard deviation for the measurement of 0.32 mg.L-1 tannin (n = 11) was 2.3%. The proposed method has been successfully applied to the determination of tannins in tea. The results obtained were compared with those provided by the Folin-Ciocalteu method.