Packaging and storage—
Preserve in tight, light-resistant containers.
Identification—
Place a quantity of finely powdered Tablets, equivalent to about 4 mg of estradiol, in a screw-capped, 20-mL vial. Add 10 mL of chloroform, and sonicate for 2 minutes. Filter through medium-porosity filter paper. Apply 20 µL each of this solution and a Standard solution of
USP Estradiol RS in chloroform containing 0.4 mg per mL to a suitable thin-layer chromatographic plate (see
Chromatography 
621
) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a lined chamber with a solvent system consisting of a mixture of toluene and acetone (4:1) until the solvent front has moved 10 cm beyond the starting line. Remove the plate from the developing chamber, mark the solvent front, and allow to air-dry. Spray the plate with a mixture of methanol and sulfuric acid (1:1), and heat at 100
for about 5 minutes: the principal spots obtained from the test solution and the Standard solution have the same color and
RF value.
Dissolution 711—
Medium:
0.3% sodium lauryl sulfate in water; 500 mL.
Apparatus 2:
100 rpm.
Time:
60 minutes.
Mobile phase—
Prepare a suitable degassed and filtered solution of water and acetonitrile (55:45).
Standard solution—
Prepare a solution of
USP Estradiol RS in methanol having an accurately known concentration of about 0.02 mg per mL. Dilute aliquots of this solution with
Medium to obtain a final solution having a concentration approximately equal to the expected concentration of drug in the
Medium, assuming 100% dissolution.
Test solution—
Use a filtered portion of the solution under test from the dissolution vessel.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 205-nm detector and a 4.6-mm × 7.5-cm column that contains packing L1. The flow rate is about 1.5 mL per minute. Chromatograph replicate injections of the
Standard preparation, and record the peak areas as directed for
Procedure: the tailing factor is not more than 2.0; and the relative standard deviation is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 100 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity of C
18H
24O
2 dissolved by comparison of the peak areas obtained from the
Test solution and the
Standard solution.
Tolerances—
Not less than 75% (Q) of the labeled amount of C18H24O2 is dissolved in 60 minutes.
Assay—
Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system—
Proceed as directed in the
Assay under
Estradiol.
Assay preparation—
Weigh and finely powder not fewer than 10 Tablets. Transfer a portion of the powder, equivalent to about 8 mg of estradiol, to a 100-mL volumetric flask. Add 4 mL of water, and swirl. Add 10.0 mL of Internal standard solution and about 60 mL of methanol. Shake by mechanical means for 15 minutes, dilute with methanol to volume, mix, and allow the solids to settle. Filter a portion, discarding the first 10 mL of the filtrate. Mix 5.0 mL of the subsequent filtrate with 5.0 mL of methanol and 10.0 mL of water.
Procedure—
Proceed as directed for
Procedure in the
Assay under
Estradiol. Calculate the quantity, in mg, of C
18H
24O
2 in the portion of Tablets taken by the formula:
0.4C(RU / RS),
in which the terms are as defined therein.
