Standard preparation— Weigh accurately about 26mg of USP Ephedrine Sulfate RS,transfer to a 50-mLvolumetric flask with the aid of 10mLof water,add methanol to volume,and mix.Pipet 5mLof the resulting solution into a 100-mLvolumetric flask,dilute with water to volume,and mix.

Assay preparation— Transfer an accurately measured volume of Nasal Solution,equivalent to about 26mg of ephedrine sulfate,to a 50-mLvolumetric flask,dilute with a 1in 5mixture of water in methanol to volume,and mix.Pipet 5mLof the resulting solution into a 100-mLvolumetric flask,dilute with water to volume,and mix.

Procedure— Transfer 5-mLportions of the Assay preparationand the Standard preparationto separate glass-stoppered,50-mLcentrifuge tubes.Add 1mLof saturated sodium carbonate solution and 2mLof sodium metaperiodate solution (1in 50)to each tube,mix,and allow to stand for 10minutes.Pipet 20mLof n-hexane into each tube,shake for 30seconds,and allow the phases to separate.Concomitantly determine the absorbances of the n-hexane extracts in 1-cm cells at the wavelength of maximum absorbance at about 242nm,with a suitable spectrophotometer,using n-hexane as the blank.Calculate the quantity,in mg,of (C10H15NO)2·H2SO4in each mLof the Nasal Solution taken by the formula: in which Vis the volume,in mL,of Nasal Solution taken,Cis the concentration,in µg per mL,of USP Ephedrine Sulfate RSin the Standard preparation,and AUand ASare the absorbances of the hexane extracts of the Assay preparationand the Standard preparation,respectively.