Bismuth Subsalicylate BP Grade

C7H5BiO4
362.1 -- 14882-18-9
Ph Eur

DEFINITION
Complex of bismuth and salicylic acid.
Content: 56.0 per cent to 59.4 per cent of Bi (Ar 209.0) (dried substance).

CHARACTERS
Appearance: White or almost white powder.
Solubility: Practically insoluble in water and in alcohol. It dissolves in mineral acids with decomposition.

IDENTIFICATION
A. To 0.5 g add 10 ml of hydrochloric acid. Heat on a boiling water-bath for 5 min. Cool and filter. Retain the filtrate for identification test B. Wash the residue with dilute hydrochloric acid and then with water. Dissolve the residue in 0.5-1 ml of dilute sodium hydroxide solution. Add 15 ml of water. Neutralise with dilute hydrochloric acid. The solution gives reaction (a) of salicylates.
B. The filtrate obtained in identification test A gives reaction (b) of bismuth.

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 ± 25C 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 2.0 g with 30 ml of ether for 1 min and filter. To the filtrate add 30 ml of alcohol and 0.1 ml of thymol blue solution. Not more than 0.35 ml of 0.1 M sodium hydroxide is required to change the colour of the indicator to blue.
Chlorides: Maximum 200 ppm.
Nitrates: Maximum 0.4 per cent.
Copper: Maximum 50.0 ppm.
Lead: Maximum 20.0 ppm.
Silver: Maximum 25.0 ppm.
Soluble bismuth: Maximum 40.0 ppm.
Loss on drying: Maximum 1.0 per cent, determined on 1.000 g by drying in an oven at 105C.

ASSAY
Dissolve with heating 0.300 g in 10 ml of a mixture of 2 volumes of perchloric acid and 5 volumes of water. 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.

Bismuth Subsalicylate USP Grade

C7H5BiO4 -- 362.09
(2-Hydroxybenzoato-O1)-oxobismuth.
2-Hydroxybenzoic acid bismuth (3+) salt, basic [14882-18-9].
Bismuth Subsalicylate is a basic salt that when dried at 105 for 3 hours contains not less than 56.0 percent and not more than 59.4 percent of bismuth (Bi) and not less than 36.5 percent and not more than 39.3 percent of total salicylates.

Identification:
A: Infrared Absorption.
B: It responds to the tests for Bismuth.
pH: between 2.7 and 5.0, in a solution prepared as follows. Mix 10 g of Bismuth Subsalicylate and 90 mL of water, shake by mechanical means for 10 minutes, and filter.
Loss on drying: Dry it at 105C for 3 hours: it loses not more than 1.0% of its weight.
Limit of nitrate: 0.4%.
Arsenic: The limit is 10 µg per g.
Limit of free salicylic acid: To pass the test. (Not more than 0.2%).
Limit of copper, lead, and silver: To pass the test. (40 µg per g).