Packaging and storage—
Preserve in single-dose containers, preferably of Type I glass.
Identification—
A:
The caffeine obtained in the
Assay for caffeine herein responds to
Identification test
A under
Caffeine.
B:
Dip the end of a platinum wire into a portion of Injection, and then introduce it into a nonluminous flame: the flame is colored intensely yellow.
C:
To about 0.5 mL of Injection add a few drops of
ferric chloride TS: a salmon-colored precipitate is formed. To another portion of Injection add 3 N hydrochloric acid: a white precipitate is formed.
Bacterial endotoxins 
85
—
It contains not more than 0.7 USP Endotoxin Unit per mg of caffeine and sodium benzoate, based on the total, in mg, of the labeled amounts.
Other requirements—
It meets the requirements under
Injections 1.
Assay for caffeine—
Measure accurately a volume of Injection, equivalent to about 250 mg each of caffeine and sodium benzoate, transfer it completely with the aid of about 5 mL of water to a small separator, add 1 drop of phenolphthalein TS, and add 0.1 N sodium hydroxide, dropwise, until a permanent pink color is just produced. Shake the mixture with three or more 20-mL portions of chloroform to effect complete extraction of the caffeine, passing each chloroform extract through a small filter previously moistened with chloroform into a tared dish. (Retain the water layer for the
Assay for sodium benzoate.) Wash the stem of the separator, the filter, and the funnel with 10 mL of hot chloroform, adding the washings to the dish. Evaporate the combined chloroform solutions on a steam bath, adding 2 mL of alcohol just before the last trace of chloroform is expelled. Complete the evaporation of the solvent, dry the residue, consisting of C
8H
10N
4O
2, at 80
for 4 hours, cool, and weigh.
Assay for sodium benzoate—
To the water layer obtained in the
Assay for caffeine add 75 mL of ether and 5 drops of
methyl orange TS. Titrate with 0.1 N hydrochloric acid VS, mixing the liquids by vigorous shaking, until a permanent pink color is produced in the water layer. Each mL of 0.1 N hydrochloric acid is equivalent to 14.41 mg of C
7H
5NaO
2.
