Packaging and storage—
Preserve in tight containers.
Identification—
Dissolve about 1 g in 20 mL of water, and use the solution for the following tests.
A:
To 10 mL of the test solution add 5 mL of mercuric-potassium iodide TS: a pale yellow precipitate is formed (presence of choline).
B:
To 10 mL of the test solution add 5 drops of 6 N ammonium hydroxide and 5 mL of
silver nitrate TS: a gelatinous precipitate is formed, and it coagulates on heating (
presence of theophylline).
Chloride 
221
—
A 0.50-g portion shows no more chloride than corresponds to 0.15 mL of 0.020 N hydrochloric acid (0.02%).
Ordinary impurities 466—
Test solution:
a mixture of chloroform, alcohol, and formic acid (88:10:2).
Standard solution:
a mixture of chloroform, alcohol, and formic acid (88:10:2).
Eluant:
a mixture of chloroform, alcohol, and formic acid (88:10:2).
Visualization:
1.
Organic volatile impurities, Method I 467:
meets the requirements.
Choline content—
Dissolve about 900 mg of Oxtriphylline, accurately weighed, in 50 mL of water, and add 4 drops of a solution prepared by dissolving 30 mg of methyl red in 100 mL of methanol, adding 15 mL of methylene blue solution (1 in 1000), and mixing. Mix, and titrate with 0.1 N sulfuric acid VS to a purple endpoint. Each mL of 0.1 N sulfuric acid is equivalent to 12.12 mg of C5H15NO2. The content of choline (C5H15NO2) is between 652 mg and 693 mg per g of C7H8N4O2 found in the Assay. Retain the final solution for the Assay for theophylline.
Assay for theophylline—
To the solution retained in the
Choline content add 35 mL of
silver nitrate TS, swirl gently to promote complete precipitation, and titrate with 0.1 N sodium hydroxide VS to a green endpoint. Each mL of 0.1 N sodium hydroxide is equivalent to 18.02 mg of C
7H
8N
4O
2.
;)
for 4 hours: it loses not more than 1.0% of its weight.