Bismuth Subgallate

Synonyms: 2,7-Dihydroxy-1,3,2-benzodioxabismole-5-carboxylic acid, Bismuth(III) gallate basic hydrate, Dermatol

CAS Number: 99-26-3,

Molecular Weight: 394.09,

Chemical Formula: C7H5BiO6,

EINECS EC Number: 202-742-2 ,

FEMA: ----

Bismuth Subgallate USP Grade

C7H5BiO6  -- 394.09
Gallic acid bismuth basic salt [99-26-3].
Bismuth Subgallate is a basic salt which, when dried at 105 for 3 hours, contains the equivalent of not less than 52.0 percent and not more than 57.0 percent of Bi2O3.
Packaging and storage: Preserve in tight, light-resistant containers.


A: When heated to redness, it at first chars, leaving finally a yellow residue. This residue responds to the tests for Bismuth.
B: Agitate thoroughly about 100 mg with an excess of hydrogen sulfide, filter, and boil the filtrate to expel the dissolved gas. Cool, and add 1 drop of ferric chloride: a purplish blue mixture is produced.
Loss on drying: Dry it at 105 for 3 hours. It loses not more than 7.0% of its weight.
Limit of nitrate: Mix about 100 mg with 5 mL of 2 N sulfuric acid and 5 mL of ferrous sulfate, filter the mixture, and carefully superimpose the filtrate, without mixing, on 5 mL of sulfuric acid, in a test tube: no reddish brown color appears at the zone of contact of the two liquids.
Arsenic: Triturate 400 mg with an equal weight of calcium hydroxide, and ignite. Dissolve the residue in 5 mL of 3 N hydrochloric acid: the solution without further treatment meets the requirements of the test for Arsenic 211 (7.5 ppm).
Copper, Lead, and Silver: To pass the test.
Limit of alkalies and alkaline earths: Boil 1.0 g with 20 mL of a mixture of equal volumes of 6 N acetic acid and water, cool, and filter. Precipitate the bismuth from the filtrate by the addition of hydrogen sulfide, boil the mixture, and filter. Add 5 drops of sulfuric acid to the filtrate, evaporate to dryness, and ignite to constant weight: the weight of the residue does not exceed 5 mg (0.5%).
Free gallic acid: Shake 1.0 g with 20 mL of alcohol for 1 minute, filter and evaporate the filtrate to dryness on a steam bath, and dry the residue at 105 for 1 hour: the weight of the residue does not exceed 5 mg (0.5%).
Assay: Dry about 1 g of Bismuth Subgallate at 105C for 3 hours, then weigh accurately and ignite in a porcelain crucible. Allow it to cool and add nitric acid to the residue, dropwise, warming until complete solution has been effected. Evaporate the solution to dryness and carefully ignite the residue to constant weight. From the weight of the residue so obtained, determine the percentage of Bi2O3 in the portion of Bismuth Subgallate taken.

Bismuth Subgallate BP Grade

394.1 --149-91-7
Ph Eur


Complex of bismuth and gallic acid.
Content: 48.0 per cent to 51.0 per cent of Bi (Ar 209.0) (dried substance).


Appearance: Yellow powder.
Solubility: Practically insoluble in water and in alcohol. It dissolves in mineral acids with decomposition and in solutions of alkali hydroxides, producing a reddish-brown liquid.


A. Mix 0.1 g with 5 ml of water R and 0.1 ml of phosphoric acid R. Heat to boiling and maintain boiling for 2 min. Cool and filter. To the filtrate, add 1.5 ml of ferric chloride solution, a blackish-blue colour develops.
B. It gives reaction (b) of bismuth (2.3.1).


Solution S: In a porcelain or quartz dish, ignite 1.0 g, increasing the temperature very gradually. Heat in a muffle furnace at 600 ± 50C for 2 h. Cool and dissolve the residue with warming in 4 ml of a mixture of equal volumes of lead-free nitric acid and water and dilute to 20 ml with water.
Acidity: Shake 1.0 g with 20 ml of water R for 1 min and filter. To the filtrate add 0.1 ml of methyl red solution. Not more than 0.15 ml of 0.1 M sodium hydroxide is required to change the colour of the indicator to yellow.
Chlorides: Maximum 200 ppm.
Nitrates: Maximum 0.2 per cent.
Copper: Maximum 50.0 ppm.
Lead: Maximum 20.0 ppm.
Silver: Maximum 25.0 ppm.
Substances not precipitated by ammonia: Maximum 1.0 per cent.
Loss on drying: Maximum 7.0 per cent, determined on 1.000 g by drying in an oven at 105C for 3 h.


To 0.300 g add 10 ml of a mixture of equal volumes of nitric acid and water, heat to boiling and maintain boiling for 2 min. Add 0.1 g of potassium chlorate, heat to boiling and maintain boiling for 1 min. Add 10 ml of water and heat until the solution becomes colourless. To the hot solution, add 200 ml of water and 50 mg of xylenol orange triturate.
Titrate with 0.1 M sodium edta until a yellow colour is obtained.
1 ml of 0.1 M sodium edta is equivalent to 20.90 mg of Bi.