A: Thin-Layer Chromatographic Identification Test á201ñ—

B: The relative retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

Medium— Add 1.0mLof polyoxyethylene (23)lauryl ether solution,prepared by dissolving 50g in 100mLof water,to 0.225Mhydrochloric acid;4000mL.

Apparatus 2: 75rpm.

Time: 60minutes.

Mobile phase— Prepare as directed in the Assayunder Thalidomide.

Internal standard solution— Prepare a solution of phenacetin in acetonitrile containing about 375µg per mL.Pipet 20.0mLof this solution into a 100-mLvolumetric flask,add 10.0mLof phosphoric acid solution (1in 100),dilute with water to volume,and mix.

Standard solution— Dissolve an accurately weighed quantity of USP Thalidomide RSin acetonitrile to obtain a solution having a known concentration of about 0.25mg per mL.Pipet 10.0mLof this solution into a 100-mLvolumetric flask,add 10.0mLof phosphoric acid solution (1in 100),dilute with water to volume,and mix.Add 5.0mLof Internal standard solutionto 20.0mLof this solution,and mix.This solution contains about 0.02mg of USP Thalidomide RSper mL.

Test solution— Add 5.0mLof Internal standard solutionto each 20.0mLof filtered solution under test,and mix.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of C13H10N2O4dissolved by the formula: in which Cis the concentration,in mg per mL,of USP Thalidomide RSin the Standard solution;and RUand RSare the peak area ratios of thalidomide to the internal standard obtained from the Test solutionand the Standard solution,respectively.

Tolerances— Not less than 70%(Q)of the labeled amount of C13H10N2O4is dissolved in 60minutes.

Mobile phase,Internal standard preparation,Standard preparation,and Chromatographic system— Prepare as directed in the Assayunder Thalidomide.

Assay preparation— Remove,as completely as possible,the contents of not fewer than 20Capsules,and weigh accurately.Mix the combined contents,and transfer an accurately weighed portion of the powder,equivalent to about 50mg of thalidomide,to a 100-mLvolumetric flask,add 80mLof acetonitrile to dissolve,and sonicate for about 20minutes.Dilute with acetonitrile to volume,and mix.Transfer 20.0mLof this solution and 5.0mLof Internal standard preparationto a 100-mLvolumetric flask,add 10.0mLof phosphoric acid solution (1in 100),dilute with water to volume,and mix.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of thalidomide (C13H10N2O4)in the portion of Capsules taken by the formula: in which Cis the concentration,in mg per mL,of USP Thalidomide RSin the Standard preparation;and RUand RSare the peak area ratios of thalidomide to the internal standard obtained from the Assay preparationand the Standard preparation,respectively.