Dissolution 
711
—
Medium:
sodium lauryl sulfate solution (5 in 100); 1000 mL.
Apparatus 2:
100 rpm.
Time:
180 minutes.
Determine the amount of C12H15ClO3 dissolved by employing the following method.
Mobile phase—
Prepare a degassed and filtered mixture of methanol and water (80:20).
Standard solution—
Transfer about 20 mg of
USP Clofibrate RS, accurately weighed, to a 50-mL volumetric flask. Add 20 mL of methanol, mix to dissolve the clofibrate, dilute with water to volume, and mix. Dilute an aliquot quantitatively with methanol to obtain a final solution having a known concentration of about 80 µg per mL.
Test solution—
Dilute a 5.0-mL portion of the solution under test to 25.0 mL, using methanol. Allow to stand for 5 minutes, and filter.
Chromatographic system—
The liquid chromatograph is equipped with a 226-nm detector and a 4-mm × 30-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the
Standard solution, and record the peak responses as directed for
Procedure: the tailing factor is not more than 1.5; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal portions (about 20 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the amount of C
12H
15ClO
3 dissolved.
Tolerances—
Not less than 80% (Q) of the labeled amount of C12H15ClO3 is dissolved in 180 minutes.
Assay—
Proceed with Capsules as directed in the
Assay under
Clofibrate, using the following as the
Assay preparation: Weigh accurately not less than 20 Capsules in a tared weighing bottle. With a sharp blade, carefully open the Capsules, without loss of shell material, and transfer the contents to a 100-mL beaker. Remove any liquid from the emptied capsules by washing with several small portions of ether. Discard the washings, and allow the capsules to dry in a jet of dry air until the odor of ether no longer is perceptible. Weigh the empty capsules in the tared weighing bottle, and calculate the average net weight per capsule. Transfer an accurately weighed amount of capsule contents, equivalent to about 200 mg of clofibrate, to a 100-mL volumetric flask, add methanol to volume, and mix. Transfer 10.0 mL of this solution to the
Ion-exchange column, and collect the eluate in a 100-mL volumetric flask. Rinse the column with 25 mL of methanol, collect the rinsings in the volumetric flask, dilute with methanol to volume, and mix. Transfer 5.0 mL of this solution to a 50-mL volumetric flask, dilute with methanol to volume, and mix. Calculate the quantity, in mg, of C
12H
15ClO
3 in the portion of Capsules taken by the formula:
10C(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Clofibrate RS in the
Standard preparation; and
AU and
AS are the absorbances of the
Assay preparation and the
Standard preparation, respectively.
