Standard preparation
Weigh accurately about 32.5mg of
USP Hydrocortisone Hemisuccinate RS,and transfer it to a 50-mLvolumetric flask.Add by pipet 5.0mLof
Internal standard solutionand 5.0mLof a solution of glacial acetic acid in chloroform (3in 100)containing in each mLan accurately known quantity of about 0.30mg of
USP Hydrocortisone RS.Dilute with glacial acetic acid in chloroform (3in 100)to volume,and mix.
Procedure
Proceed as directed for
Procedurein the
Assayunder
Hydrocortisone Hemisuccinate.The order of elution of peaks is that from the internal standard,hydrocortisone hemisuccinate,and successive smaller peaks representing free hydrocortisone and hydrocortisone 17-hemisuccinate,whose relative retention times are about 1.0,1.5,2.0,and 2.5,respectively.Measure the areas of the peaks from the internal standard,hydrocortisone hemisuccinate,and hydrocortisone 17-hemisuccinate.Calculate the ratio of the summation of the areas of the hydrocortisone hemisuccinate and hydrocortisone 17-hemisuccinate peaks to that of the internal standard in the chromatogram obtained from the
Standard preparation,
RS,and the same ratio in the chromatogram obtained from the
Assay preparation,
RU.Calculate the quantity,in mg,of hydrocortisone (C
21H
30O
5)in the portion of constituted solution taken by the formula:
0.784(100C)(RU/RS),
in which 0.784is the ratio of the molecular weight of hydrocortisone to that of hydrocortisone hemisuccinate;
Cis the concentration,in mg per mL,of
USP Hydrocortisone Hemisuccinate RSin the
Standard preparation;and
RUand
RSare the ratios as defined above,and to this quantity add the amount,in mg,of free hydrocortisone found in the test for
Free hydrocortisone.