(tan' ik as' id).
Tannic acid; Tannin [1401-55-4].
» Tannic Acid is a tannin usually obtained from nutgalls, the excrescences produced on the young twigs of Quercus infectoria Oliver, and allied species of Quercus Linné (Fam. Fagaceae), from the seed pods of Tara (Caesalpinia spinosa), or from the nutgalls or leaves of sumac (any of a genus Rhus).
Packaging and storage Preserve in tight, light-resistant containers.
A: To 2 mL of a solution (1 in 10) add 1 drop of ferric chloride TS: a bluish black color or precipitate results.
B: To a solution (1 in 10) add an equal volume of gelatin solution (1 in 100): a precipitate is formed.
Loss on drying 731 Dry it at 105 for 2 hours: it loses not more than 12.0% of its weight.
Residue on ignition 281: not more than 1.0%.
Arsenic, Method II 211: 3 ppm.
Heavy metals, Method II 231: 0.004%.
Gum or dextrin Dissolve 2 g in 10 mL of hot water: the solution is not more than slightly turbid. Cool, filter, and divide the filtrate into two equal portions. To one portion add 10 mL of alcohol: no turbidity is produced.
Resinous substances To a portion of the filtrate obtained in the test for Gum or dextrin add 10 mL of water: no turbidity is produced.