Tannic Acid

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Tannin;

Tannic acid

CAS RN®: 1401-55-4; UNII: 28F9E0DJY6.

1 DEFINITION

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 L. (Fam. Fagaceae), from the seed pods of tara (Caesalpinia spinosa), or from the nutgalls or leaves of sumac (any of a genus Rhus).

2 IDENTIFICATION

A. Sample solution: 100 mg/mL of Tannic Acid in water

Analysis: To 2 mL of the Sample solution, add 1 drop of ferric chloride TS.

Acceptance criteria: A bluish black color or precipitate results

B. Sample solution: 100 mg/mL of Tannic Acid in water

Analysis: Add an equal volume of 10 mg/mL of gelatin in water to the Sample solution.

Acceptance criteria: A precipitate is formed.

3 OTHER COMPONENTS

3.1 Gum or Dextrin

Sample solution: Dissolve 2 g of Tannic Acid in 10 mL of hot water. The solution is not more than slightly turbid. Cool, filter, and divide the filtrate into two equal portions. Use a portion of the filtrate.

Analysis: Add 10 mL of alcohol to the Sample solution.

Acceptance criteria: No turbidity is produced.

3.2 Resinous Substances

Sample solution: A portion of the filtrate obtained in the test for Gum or Dextrin

Analysis: Add 10 mL of water to the Sample solution.

Acceptance criteria: No turbidity is produced.

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 1.0%

Delete the following:

Arsenic 〈211〉, Procedures, Method II: NMT 3 ppm (USP 1-Aug-2022)

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry at 105° for 2 h.

Acceptance criteria: NMT 12.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers.