(Official January 1, 2007)

Standard preparation— Dissolve an accurately weighed quantity of USP Ephedrine Sulfate RS in 0.1 N sulfuric acid to obtain a solution having a known concentration of about 20 µg per mL.

Assay preparation— Transfer 5 mL of Oral Solution to a separator, add 1 mL of 1 N sulfuric acid, and extract with 10 mL of chloroform. Discard the extract, and add 5 mL of potassium carbonate solution (1 in 5). After gas evolution has ceased, extract the solution with three 10-mL portions of chloroform, and combine the extracts in a second separator. Extract the chloroform solution with 50.0 mL of 0.1 N sulfuric acid. Filter the acid layer through paper, and dilute 5.0 mL of it with 0.1 N sulfuric acid to 100.0 mL.

Procedure— Proceed as directed for Procedure in the Assay under Ephedrine Sulfate Capsules. Calculate the quantity, in mg, of ephedrine sulfate [(C10H15NO)2·H2SO4] in the portion of Oral Solution taken by the formula: in which C is the concentration, in µg per mL, of USP Ephedrine Sulfate RS in the Standard preparation; and AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.