Internal standard solution— Prepare a solution of 1,3,5-triphenylbenzene in chloroform containing about 0.25mg per mL.

Standard preparation— Prepare a solution of USP Mibolerone RSin Internal standard solutionhaving a known concentration of about 0.5mg per mL.

Assay preparation— Transfer an accurately weighed portion of Oral Solution,equivalent to about 1000µg of mibolerone,to a 125-mLseparator containing 60mLof water,and swirl to disperse.Add 30mLof methylene chloride,shake gently for about 5minutes,and allow the phases to separate.Drain the lower methylene chloride layer through a pledget of methylene chloride-washed cotton into a 50-mLconical flask.Evaporate to dryness under a current of air.Re-extract the aqueous layer remaining in the separator with an additional 30-mLportion of methylene chloride,draining the filtered methylene chloride extract into the 50-mLconical flask,and evaporating it to dryness.Add 2.0mLof Internal standard solution,and swirl to dissolve.

Chromatographic system (see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector and a 3-mm ×61-cm column packed with 1%liquid phase G6on support S1AB.The column is maintained at about 175and the detector at 195to 225.Helium is used as the carrier gas at a flow rate of about 60mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are about 0.6for the internal standard and 1.0for mibolerone;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 2µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in µg,of mibolerone (C20H30O2)in each mLof the Oral Solution taken by the formula: in which Cis the concentration,in mg per mL,of USP Mibolerone RSin the Standard preparation;WUis the weight,in g,of Oral Solution taken to prepare the Assay preparation;Dis the specific gravity of the Oral Solution;and RUand RSare the ratios of the peak height response of the mibolerone peak to the internal standard peak obtained from the Assay preparationand the Standard preparation,respectively.