Dissolution 
711
—
Medium:
0.1 N hydrochloric acid; 1000 mL.
Apparatus 2:
50 rpm.
Time:
60 minutes.
Chromatographic system—
The liquid chromatograph is fitted with a 232-nm detector and a 4-mm × 30-cm column that contains packing L7. The mobile phase is a degassed mixture of methanol, water, and glacial acetic acid (60:40:1), and the flow rate is about 2 mL per minute. In a suitable system, the relative standard deviation observed following replicate injections is not more than 3.0%.
Procedure—
Inject an accurately measured volume (about 10 µL) of a filtered portion of the solution under test into the chromatograph by means of a microsyringe or a sampling valve, record the chromatogram, and measure the response for the major peak. Calculate the quantity of C
15H
11ClN
2O
2 dissolved in comparison with a similarly chromatographed Standard solution having a known concentration of
USP Oxazepam RS in 0.1 N hydrochloric acid.
[NOTE—A volume of alcohol not exceeding 10% of the final total volume of the Standard solution may be used to dissolve the Reference Standard.
]
Tolerances—
Not less than 80% (Q) of the labeled amount of C15H11ClN2O2 is dissolved in 60 minutes.
Assay—
Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 50 mg of oxazepam, to a medium-porosity, sintered-glass funnel that is fitted into a small suction flask, and proceed as directed in the
Assay under
Oxazepam Capsules, beginning with “Add 25 mL of alcohol.” Calculate the quantity, in mg, of C
15H
11ClN
2O
2 in the portion of Tablets taken by the formula:
12.5C(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Oxazepam RS in the Standard solution, and
AU and
AS are the absorbances of the solution from the Tablets and the Standard solution, respectively.
