Packaging and storage—
Preserve in tight containers.
Labeling—
Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
Completeness of solution—
Mix 1.0 g with 10 mL of carbon dioxide-free water: after 1 minute, the solution is clear and free from undissolved solid.
Identification—
A:
Dissolve about 50 mg of Phenobarbital Sodium in 15 mL of water in a separator, add 2 mL of hydrochloric acid, shake, and extract the liberated phenobarbital with four 25-mL portions of chloroform. Filter the combined extracts through a pledget of cotton or other suitable filter into a beaker, and wash the separator and the filter with several small portions of chloroform. Evaporate a 50-mL portion of the chloroform solution of phenobarbital on a steam bath with the aid of a current of air. Add 10 mL of ether, again evaporate, and dry the residue at 105
for 2 hours: the IR absorption spectrum of a potassium bromide dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of
USP Phenobarbital RS.
B:
Ignite about 200 mg: the residue effervesces with acids, and responds to the tests for
Sodium 
191
.
C:
The relative retention time of the major peak in the chromatogram of the
Assay preparation corresponds to that in the chromatogram of the
Standard preparation, as obtained in the
Assay.
Heavy metals 231—
Dissolve 2.0 g in 52 mL of water. Add slowly, with vigorous stirring, 8 mL of 1 N hydrochloric acid, and filter, discarding the first 5 mL of the filtrate. Dilute 20 mL of the subsequent filtrate with water to 25 mL: the limit is 0.003%.
Organic volatile impurities, Method I 467:
meets the requirements.
Assay—
pH 4.5 Buffer solution, Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system—
Prepare as directed in the
Assay under
Phenobarbital.
Assay preparation—
Transfer about 22 mg of Phenobarbital Sodium, accurately weighed, to a conical flask, add 15.0 mL of Internal standard solution, mix, and sonicate for 15 minutes. Pass through a membrane filter having a 0.5-µm or finer porosity before use.
Procedure—
Proceed as directed for
Procedure in the
Assay under
Phenobarbital. Calculate the quantity, in mg, of C
12H
11N
2NaO
3 in the portion of Phenobarbital Sodium taken by the formula:
(254.22 / 232.24)(W)(RU / RS),
in which 254.22 and 232.24 are the molecular weights of phenobarbital sodium and phenobarbital, respectively; and the other terms are as defined therein.
