Identification—
Place a volume of Nasal Solution, equivalent to about 2.5 mg of oxymetazoline hydrochloride, in a 60-mL separator, and add water to make about 10 mL. Add 2 mL of sodium carbonate solution (1 in 10), extract with 10 mL of chloroform, and transfer the chloroform extract to a second 60-mL separator. Extract the chloroform solution with 10 mL of 0.1 N hydrochloric acid, allow to separate, and discard the chloroform layer. Transfer 8 mL of the acidic aqueous layer to a test tube, neutralize by the dropwise addition of 1 N sodium hydroxide, add 1 drop of 1 N sodium hydroxide in excess, and mix. Add a few drops of
sodium nitroferricyanide TS and 2 drops of sodium hydroxide solution (15 in 100), mix, and allow to stand for 10 minutes. Add 0.1 N hydrochloric acid dropwise until the pH is between 8 and 9, and allow to stand for 10 minutes: a violet color develops.
Assay—
Standard preparation—
Prepare a solution of
USP Oxymetazoline Hydrochloride RS in
Mobile phase, having a known concentration, approximately equal to the labeled concentration of the Nasal Solution.
Assay preparation—
Use Nasal Solution.
Chromatographic system
and
Procedure—Proceed as directed in the
Assay under
Oxymetazoline Hydrochloride, except to calculate the quantity, in mg, of C
16H
24N
2O·HCl in each mL of the Nasal Solution taken by the formula:
C(rU / rS),
in which the terms are as defined therein.
791
:
between 4.0 and 6.5.