(Ph. Eur. monograph 1494)
4[BiNO3(OH)2],BiO(OH) 1462 1304-85-4
DEFINITION
Bismuth hydroxide nitrate oxide.
Content
71.0 per cent to 74.0 per cent of Bi (Ar 209.0) (dried substance).
CHARACTERS
Appearance
White or almost white powder.
Solubility
Practically insoluble in water and in ethanol (96 per cent). It dissolves in mineral acids with decomposition.
IDENTIFICATION
A. Dilute 1 mL of solution S (see Tests) to 5 mL with water R and add 0.3 mL of potassium iodide solution
R. A black precipitate is formed which dissolves into an orange solution with the addition of 2 mL of potassium iodide solution R.
B. It gives reaction (b) of bismuth (2.3.1).
C. It gives the reaction of nitrates (2.3.1).
D. pH (2.2.3): maximum 2.0.
Place 1.00 g in a 20 mL volumetric flask and add 2.0 mL of lead-free nitric acid R. Allow acid attack to take place without heating and if necessary warm slightly at the end to completely dissolve the test sample. Add 10 mL of water R, shake and add, in small fractions, 4.5 mL of lead-free ammonia R; shake and allow to cool. Dilute to 20.0 mL with water R, shake again and allow the solids to settle. Use the supernatant.
TESTS
Solution S
Shake 5.0 g with gentle heating in 10 mL of water R and add 20 mL of nitric acid R. Heat until dissolution, cool and dilute to 100 mL with water R.
Acidity
Suspend 1.0 g in 15 mL of water R and shake several times. Allow to stand for 5 min and filter. To 10 mL of the filtrate, add 0.5 mL of phenolphthalein solution R1. Not more than 0.5 mL of 0.1 M sodium hydroxide is required to change the colour of the indicator to pink.
Chlorides (2.4.4)
Maximum 200 ppm.
To 5.0 mL of solution S, add 3 mL of nitric acid R and dilute to 15 mL with water R.
Substances not precipitated by ammonia
Maximum 1.0 per cent.
To 20 mL of solution S, add concentrated ammonia R until an alkaline reaction is produced and filter. Wash the residue with water R, and evaporate the combined filtrate and washings to dryness on a water-bath. To the residue, add 0.3 mL of dilute sulfuric acid R and ignite. The residue weighs a maximum of 10 mg.
Loss on drying (2.2.32)
Maximum 3.0 per cent, determined on 1.000 g by drying in an oven at 105 °C.
ASSAY
Dissolve with heating 0.250 g in 10 mL of a mixture of 2 volumes of perchloric acid R and 5 volumes of water R. To the hot solution, add 200 mL of water R and 50 mg of xylenol orange triturate R. Titrate with 0.1 M sodium edetate until a yellow colour is obtained.
1 mL of 0.1 M sodium edetate is equivalent to 20.90 mg of Bi.
