A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

Test solution: 10 mg per mL, in alcohol.

Solution A— Prepare a filtered and degassed mixture of methanol and water (55:45).

Solution B— Use methanol.

Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography 621).

System suitability solution— Dilute a volume of the Test solution quantitatively, and stepwise if necessary, with methanol to obtain a solution having a concentration of about 0.005 mg of methyltestosterone per mL.

Test solution— Dissolve an accurately weighed quantity of Methyltestosterone in methanol to obtain a solution containing about 0.5 mg per mL.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The flow rate is 1 mL per minute. The chromatograph is programmed as follows. Chromatograph the Test solution and the System suitability solution, and record the peak responses as directed for Procedure: the column efficiency is not less than 33,000 theoretical plates; and the relative standard deviation for replicate injections for the methyltestosterone peak in the chromatogram of the Test solution is not more than 2.0%; and the signal-to-noise ratio of the methyltestosterone peak in the chromatogram of the System suitability solution is not less than 100.

Procedure— Inject a volume (about 5 µL) of the Test solution into the chromatograph, record the chromatogram, and measure all of the peak areas. Calculate the percentage of each impurity in the portion of Methyltestosterone taken by the formula: in which ri is the peak response for each impurity; and rs is the sum of the responses of all the peaks, disregarding any impurity having a peak less than 0.05%. Not more than 0.5% of any individual impurity is found, and not more than 1.0% of total impurities is found.

Solvent: dimethyl sulfoxide.

(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and water (55:45). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Transfer about 25 mg of USP Methyltestosterone RS, accurately weighed, to a 100-mL volumetric flask, dilute with methanol to volume, and mix. Pipet 8 mL of this solution into a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix to obtain the Standard preparation having a known concentration of about 20 µg per mL.

Assay preparation— Transfer about 50 mg of Methyltestosterone, accurately weighed, to a 100-mL volumetric flask, dilute with methanol to volume, and mix. Pipet 8 mL of this solution to a 200-mL volumetric flask, dilute with Mobile phase to volume, and mix.

System suitability preparation— Prepare a solution of testosterone in methanol containing about 250 µg per mL. Dilute 4 mL of this solution with the Standard preparation to 50 mL, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 241-nm detector and a 4-mm × 25-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation and the System suitability preparation, and record the peak responses as directed for Procedure: the relative retention times are about 0.8 for testosterone and 1.0 for methyltestosterone; the resolution, R, between testosterone and methyltestosterone is not less than 2.0; the column efficiency determined from the analyte peak is not less than 2000 theoretical plates; the tailing factor for the analyte peak is not more than 2.7; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 50 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 C20H30O2 in the portion of Methyltestosterone taken by the formula: in which C is the concentration, in mg per mL, of USP Methyltestosterone RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.