A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Test solution: 10mg 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 Aand Solution Bas directed for Chromatographic system.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

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

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

Chromatographic system (see Chromatography á621ñ)— 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 1mLper 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 33,000theoretical 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 solutionis not less than 100.

Procedure— Inject a volume (about 5µL)of the Test solutioninto 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 riis the peak response for each impurity;and rsis 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.

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and water (55:45).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

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

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

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

Chromatographic system(see Chromatography á621ñ)— 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 1mLper minute.Chromatograph the Standard preparationand the System suitability preparation,and record the peak responses as directed for Procedure:the relative retention times are about 0.8for testosterone and 1.0for 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 2000theoretical 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 50µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C20H30O2in the portion of Methyltestosterone taken by the formula: in which Cis the concentration,in mg per mL,of USP Methyltestosterone RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.