Solution— Place 5 mL of Oral Suspension in a separator containing 20 mL of 0.1 N sodium hydroxide, and extract with 25 mL of chloroform. Pass the extract through anhydrous sodium sulfate supported on filter paper into a beaker. Wash the anhydrous sodium sulfate with 10 mL of chloroform, and add the washing to the extract. Evaporate the chloroform extract with the aid of a stream of nitrogen to dryness. Dissolve the residue in 10 mL of methylene chloride.

for oral suspension packaged in single-unit containers: meets the requirements.

for oral suspension packaged in multiple-unit containers: meets the requirements.

Mobile phase, System suitability solution, Standard preparation, and Chromatographic system— Prepare as directed in the Assay under Carbamazepine.

Assay preparation— Transfer an accurately measured volume of freshly mixed Oral Suspension, equivalent to about 200 mg of carbamazepine, to a 100-mL volumetric flask, add about 70 mL of methanol, shake by mechanical means for about 30 minutes, sonicate for about 2 minutes, dilute with methanol to volume, and mix. Allow the solution to stand for about 10 minutes, transfer 10.0 mL of the clear solution to a 100-mL volumetric flask, dilute with methanol to volume, and mix. This is the final Assay preparation. For system suitability determination, transfer 10.0 mL of this solution to a suitable container, add 10.0 mL of System suitability solution, and mix.

Procedure— Proceed as directed in the Assay under Carbamazepine. Calculate the quantity, in mg, of carbamazepine (C15H12N2O) in the portion of Oral Suspension taken by the formula: in which the terms are as defined therein.