Standard preparation— Prepare as directed for Standard Preparation under Assay for Steroids 351, using USP Hydrocortisone RS.

Assay preparation— Transfer to a separator an accurately weighed quantity of Injectable Suspension, equivalent to about 50 mg of hydrocortisone, using a total of 25 mL of water to effect the transfer. Extract with four 40-mL portions of chloroform, filtering each portion through chloroform-washed cotton into a 200-mL volumetric flask. Add chloroform to volume, and mix. Pipet 20 mL of this solution into a 100-mL volumetric flask, add chloroform to volume, and mix. Pipet 10 mL of the resulting solution into a glass-stoppered, 100-mL conical flask, evaporate on a steam bath just to dryness, cool, and dissolve the residue in 50.0 mL of alcohol.

Procedure— Proceed as directed for Procedure under Assay for Steroids 351. Calculate the quantity, in mg, of C21H30O5 in the portion of Injectable Suspension taken by the formula: