Loss on drying 
731
—
Dry about 1 g, accurately weighed, in a capillary-stoppered bottle in vacuum at a pressure not exceeding 5 mm of mercury at 60
for 3 hours: it loses not more than 0.5% of its weight.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture of water, tetrahydrofuran, and methanol (60:25:15). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Internal standard solution—
Prepare a solution of progesterone in methanol containing 0.6 mg per mL.
Standard preparation—
Prepare a solution of
USP Mibolerone RS in
Internal standard solution having a known concentration of about 0.4 mg per mL. Mix, and sonicate if necessary to achieve complete solution.
Assay preparation—
Transfer about 10 mg of Mibolerone, accurately weighed, to a 25-mL volumetric flask, dilute with Internal standard solution to volume, and mix. Sonicate if necessary to achieve complete solution.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the relative retention times are about 0.6 for mibolerone and 1.0 for progesterone; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 5 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
20H
30O
2 in the portion of Mibolerone taken by the formula:
25C(RU / RS),
in which
C is the concentration, in mg per mL, of
USP Mibolerone RS in the
Standard preparation; and
RU and
RS are the ratios of the peak responses of the mibolerone peak and the progesterone peak obtained from the
Assay preparation and the
Standard preparation, respectively.
;)
,17
)-.