Free diethylstilbestrol
Transfer 2.0mLof the Injection to a beaker containing about 20mLof water.Add 1Nphosphoric acid to adjust to a pHof 8.0,determined potentiometrically.Proceed as directed for
Procedurein the test for
Free diethylstilbestrolunder
Diethylstilbestrol Diphosphate,beginning with Transfer the solution to a separator.The limit of free diethylstilbestrol is 0.2mg per mLof Injection.
Diethylstilbestrol monophosphate
Transfer 3.0mLof Injection to a 10-mLvolumetric flask,dilute with water to volume,and mix.Transfer 1mLof this solution to a beaker containing about 20mLof water,and proceed as directed in the test for
Diethylstilbestrol monophosphateunder
Diethylstilbestrol Diphosphate,beginning with Add 1Nsodium hydroxide or 1Nphosphoric acid.The limit of diethylstilbestrol monophosphate is 2.0mg per mLof Injection.
Assay
Transfer an accurately measured volume of Injection,equivalent to about 150mg of diethylstilbestrol diphosphate,to a 200-mLvolumetric flask,add water to volume,and mix.Transfer 5.0mLof this solution to a 250-mLvolumetric flask,and dilute with water to volume,and mix.Concomitantly determine the absorbances of this solution and a Standard solution of
USP Diethylstilbestrol Diphosphate RShaving a known concentration of about 15µg per mL,and containing 1mLof 0.02Nsodium hydroxide per 100mLof solution,in 1-cm cells at the wavelength of maximum absorbance at about 241nm,with a suitable spectrophotometer,using water containing 0.5mLof 0.02Nsodium hydroxide per 100mL,as the blank.Calculate the quantity,in mg,of diethylstilbestrol diphosphate (C
18H
22O
8P
2)in each mLof the Injection taken by the formula:
3.33C(AU/AS),
in which
Cis the concentration,in µg per mL,of
USP Diethylstilbestrol Diphosphate RSin the Standard solution,and
AUand
ASare the absorbances of the solution from the Injection and the Standard solution,respectively.