Chromatographic purity
Solvent
Prepare a mixture of chloroform and methanol (9:1).
Standard solutions
Dissolve an accurately weighed quantity of
USP Danazol RS in
Solvent to obtain a solution having a known concentration of 1 mg per mL. Dilute quantitatively with
Solvent to obtain
Standard solutions having the following compositions:
Standard
solution |
Dilution |
Concentration (µg RS per mL) |
Percentage (%, for comparison with test specimen) |
A |
(1 in 2) |
500 |
1.0 |
B |
(1 in 4) |
250 |
0.5 |
C |
(1 in 10) |
100 |
0.2 |
D |
(1 in 20) |
50 |
0.1 |
Test solution
Dissolve an accurately weighed quantity of Danazol in Solvent to obtain a solution containing 50 mg per mL.
Procedure
Apply separately 5 µL of the
Test solution and 5 µL of each
Standard solution to a suitable thin-layer chromatographic plate (see
Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Position the plate in a chromatographic chamber and develop the chromatograms in a solvent system consisting of a mixture of cyclohexane and ethyl acetate (7:3) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate in warm, circulating air. Examine the plate under short-wavelength UV light. Expose the plate to iodine vapors for 5 minutes. Compare the intensities of any secondary spots observed in the chromatogram of the
Test solution with those of the principal spots in the chromatograms of the
Standard solutions: the sum of the intensities of secondary spots obtained from the
Test solution corresponds to not more than 1.0% of related compounds, with no single impurity corresponding to more than 0.5%.
Assay
Dissolve about 100 mg of Danazol, accurately weighed and previously dried, in about 50 mL of alcohol in a 100-mL volumetric flask, swirl until dissolved, dilute with alcohol to volume, and mix. Transfer 2.0 mL of this solution to a 100-mL volumetric flask, dilute with alcohol to volume, and mix. Similarly, dissolve an accurately weighed quantity of
USP Danazol RS in alcohol to obtain a Standard solution having a known concentration of about 20 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 285 nm, using alcohol as the blank. Calculate the quantity, in mg, of C
22H
27NO
2 in the portion of Danazol taken by the formula:
5C(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Danazol RS in the Standard solution; and
AU and
AS are the absorbances of the solution of Danazol and the Standard solution, respectively.