Gentian Violet Topical Solution

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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1 DEFINITION

Gentian Violet Topical Solution contains, in each 100 mL, NLT 0.95 g and NMT 1.05 g of gentian violet (C₂₅H₃₀ClN₃).

2 IDENTIFICATION

A.

Sample solution: 1 in 5 dilution in water

Analysis: Add 5 drops of hydrochloric acid. To 5 mL of this solution add tannic acid TS dropwise.

Acceptance criteria: A deep blue precipitate is formed.

B.

Sample solution: 1 in 5 dilution in water

Analysis: To the remaining solution from Identification test A add 500 mg of zinc dust, and warm the mixture.

Acceptance criteria: Rapid decolorization occurs. Place a drop of the decolorized solution adjacent to a drop of 6 N ammonium hydroxide on a filter paper. A blue color is produced at the zone of contact.

3 ASSAY

Procedure

Sample solution: Pipet 25 mL of Topical Solution into a 300-mL conical flask, add 25 mL of water and 10 mL of hydrochloric acid, displace the air in the flask with carbon dioxide, and pass a stream of carbon dioxide through the flask. Add 50.0 mL of 0.1 N titanium trichloride VS, heat to boiling, and boil gently for 10 min, swirling the liquid occasionally. Cool the solution, and add 5 mL of ammonium thiocyanate solution (1 in 10).

Analysis: Titrate with 0.1 N ferric ammonium sulfate VS until a faint red color is produced. Perform a blank determination. Each mL of 0.1 N titanium trichloride is equivalent to 20.40 mg of gentian violet (C₂₅H₃₀ClN₃).

Acceptance criteria: It contains, in each 100 mL, 0.95–1.05 g of gentian violet (C₂₅H₃₀ClN₃).

4 SPECIFIC TESTS

Solution of Residue in Alcohol

Sample: 10 mL

Analysis: Evaporate the Sample on a steam bath to dryness.

Acceptance criteria: The residue dissolves completely in 10 mL of alcohol.

Alcohol Determination 〈611〉: 8.0%–10.0%

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.