摘要： 分析了FeCl₃-K₃Fe（CN）₆分光光度法测定植物单宁的适用性。结果表明，在pH<2.2时的酸性介质中单宁-KFe[Fe（CN）₆]最大吸收峰在680～720nm之间，绝大多数情况下吸收峰在695nm处，比色液单宁浓度在0～80μg·ml^-1时未形成沉淀前，遵守朗伯-比耳定律。时间变异系数每分钟±0.05%,回收率94.7%～105.2%,相对误差1.2%～5.3%.该方法受在酸性条件下能将Fe³⁺还原为Fe²⁺的物质和形成沉淀的物质干扰。测定结果与靛红-高锰酸钾滴淀法相接近。

关键词: 植物成分, 单宁, 分光光度法, 铁氰化钾

Abstract: The applicability of K₃Fe(CN)₆ and visible absorptiometry in determining plant tanins was analysed. The result indicated that under acidity conditions (pH<2.2) its peak absorption wavelength lies between 680一720nm,mostly at 695 nm. The concentration of tannin in the range of 1一80μg·ml^-1 is in accord with the Lambert-Ber's Law. The Extinction coef f icient changing within 25 minutes is士0. 05%per minut,the tannin recovery rate is between 91.7% and 105.2%,and the relative error between 1. 2一5. 3%.Under acidity conditions the whole process is disturbed from those materials that are able to reduce Fe⁺³ to the Fe⁺² and those that have been precipitated. The result mentioned above is similar to that of indigored一permanganate titration.

Key words: Plant ingredient, Tannin, Visible absorptiometry, K₃Fe(CN)₆

中图分类号: 

• S13