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

CLC Number: 

• S13