Gentian Violet:

Gentian Violet Methylrosanilinium Chloride

Molecular formula: C25H30ClN3
Molecular Weight: 407.98
CAS No.: 548-62-9
EINECS EC Number: 208-953-6
Synonyms: Basic violet 3 (C.I. 42555); N-{4-{Bis-[4-(diethylamino)-phenyl]-methylene}-2,5-cyclohexadien-1-ylidene}-N-methylmethanaminium chloride; Crystal violet; Hexamethylpararosaniline chloride; Hexamethyl violet; Methyl violet.
Methanaminium, N-[4-[bis[4-(dimethylamino)phenyl]methylene]-2,5-cyclohexadien-1-ylidene]-Nmethyl-,chloride.
[4-[Bis[p-(dimethylamino)phenyl]methylene]-2,5-cyclohexadien-1-ylidene]dimethylammonium chloride.

Gentian Violet USP; Crystal Violet

Gentian Violet USP
C25H30ClN3 407.98
Methanaminium, N-[4-[bis[4-(dimethylamino)phenyl]methylene]-2,5-cyclohexadien-1-ylidene]-Nmethyl-,chloride.
C. I. Basic violet 3.
[4-[Bis[p-(dimethylamino)phenyl]methylene]-2,5-cyclohexadien-1-ylidene]dimethylammonium chloride [548-62-9].

Gentian Violet contains not less than 96.0 percent and not more than 100.5 percent of gentian violet (C25H30ClN3), calculated on the anhydrous basis.

Identification—
A: Sprinkle about 1 mg on 1 mL of sulfuric acid: it dissolves in the acid with an orange or brown red color. When this solution is diluted cautiously with water, the color changes to brown, then to green, and finally to blue.
B: Dissolve about 20 mg in 10 mL of water, and add 5 drops of hydrochloric acid. To 5 mL of this solution add tannic acid TS drop wise: a deep blue precipitate is formed.
C: To the remainder of the solution prepared for Identification test B add about 500 mg of zinc dust, and warm the mixture: rapid de-colorization 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.
Water: not more than 7.5%.
Residue on ignition: not more than 1.5%.