Abstract: Method of collidal titration was adopted to determine tannin content of valonea tannin extract. Tannin contents is correlated linearly with charge densities of the extract (expressed as titration value) in the mass range of tannin from 0.6 mg to 3.0 mg at pH 5. Average recoveries of samples XK-2 and XK-3 are 101.1% and 103.4% respectively, and relative standard deviations are 5.4% and 1.5% respectively. Compared with hide powder method, colloidal titration has the advantages of rapidity, simplicity,and low sample consumption.

Key words: colloidal titration, valonea tannin extract, tannin content