Specifications of Bismuth Subgallate USP Grade
C7H5BiO6 -- 394.09
Gallic acid bismuth basic salt CAS 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.

Identification:
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%).

Specifications of Bismuth Subgallate BP Ph Eur Grade
C7H5BiO6
394.1 --CAS 149-91-7
Ph Eur

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

IDENTIFICATION
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).

TESTS
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.