Bismuth Subgallate USP BP

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.
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%).