A: It meets the requirements under Identification—Organic Nitrogenous Bases á181ñ.

B:Ultraviolet Absorption á197Uñ—

C: It responds to the tests for Citrate á191ñ.

Mobile phase,Standard preparation,System suitability solution,and Chromatographic system— Proceed as directed in the Assay.

Test solution— Use the Assay preparationprepared as directed in the Assay.

Procedure— Inject a volume (about 50µL)of the Test solutioninto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the percentage of (Z)-isomer in the portion of Clomiphene Citrate taken by the formula: in which rZis the peak response of the (Z)-isomer in the Test solution,and riis the sum of all of the peak responses obtained from the Test solution.

Mobile phase and System suitability solution— Proceed as directed in the Assay.

Standard solution— Dissolve an accurately weighed quantity of USP Clomiphene Citrate RSinMobile phase,and dilute quantitatively,and stepwise if necessary,withMobile phase to obtain a solution having a known concentration of about 1.0µg per mL.

Test solution— Use the Assay preparation.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 290-nm detector and a 4.6-mm ×25-cm column that contains packing L26.The flow rate is about 1mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.9for clomiphene related compound A,1.0for the (Z)-isomer,and 1.2for the (E)-isomer;the resolution,R,between clomiphene related compound Aand the (Z)-isomer is not less than 1.0;and the resolution,R,between the (Z)-isomer and the (E)-isomer is not less than 1.5.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the column efficiency is not less than 2000theoretical plates for the (E)-isomer;the tailing factor is not more than 3.0for the (E)-isomer;and the relative standard deviation for replicate injections is not more than 2.0%determined from both the (E)-and (Z)-isomers.

Procedure— Inject a volume (about 50µL)of the Test solutioninto the chromatograph,record the chromatogram,and measure the peak responses.Calculate the percentage of each impurity in the portion of Clomiphene Citrate taken by the formula: in which riis the peak response for each impurity;and rsis the sum of the responses of all of the peaks:not more than 2.0%of clomiphene related compound Ais found;not more than 0.5%of any other individual impurity is found;and not more than 2.0%of total impurities is found.

Solvent: dimethyl sulfoxide.

Mobile phase— Prepare a filtered and degassed mixture of methanol,water,and triethylamine (55:45:0.3).Adjust with phosphoric acid to a pHof 2.5.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

System suitability solution— Dissolve suitable quantities of USP Clomiphene Related Compound A RSand USP Clomiphene Citrate RSin Mobile phaseto obtain a solution containing about 0.002and 0.05mg per mL,respectively.

Standard preparation— [NOTE—Use actinic glassware for all solutions.]Dissolve an accurately weighed quantity of USP Clomiphene Citrate RSin Mobile phase,and dilute quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a known concentration of about 0.05mg per mL.

Assay preparation— Transfer about 50mg of the Clomiphene Citrate,accurately weighed,to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,mix,and filter.Transfer 10.0mLof this solution to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 233-nm detector and a 4.6-mm ×25-cm column that contains packing L26.The flow rate is about 1mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.9for clomiphene related compound A,1.0for (Z)-isomer,and 1.2for (E)-isomer;and the resolution,R,between clomiphene related compound Aand (Z)-isomer is not less than 1.0and between (Z)-isomer and (E)-isomer is not less than 1.5.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 2000theoretical plates for the (E)-isomer;the tailing factor is not more than 3.0for the (E)-isomer;and the relative standard deviation for replicate injections is not more than 2.0%for both (E)-and (Z)-isomers.

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 C26H28ClNO·C6H8O7in the portion of Clomiphene Citrate taken by the formula: in which Cis the concentration,in mg per mL,of USP Clomiphene Citrate RSin the Standard preparation;rUEand rUZare the peak responses obtained from the Assay preparationfor the (E)-and (Z)-isomers,respectively;and rSEand rSZare the peak responses obtained from the Standard preparationfor the (E)-and (Z)-isomers,respectively.