Identification—
Extract a volume of Oral Solution, equivalent to about 120 mg of pseudoephedrine hydrochloride, with two 30-mL portions of ether, discard the extracts, and add 4 mL of 1 N sodium hydroxide. Extract with 30 mL of chloroform, and evaporate the chloroform on a steam bath, avoiding overheating: the pseudoephedrine so obtained melts at about 118
, the procedure for
Class I being used (see
Melting Range or Temperature 
741
), and when 50 mg is dissolved in 10 mL of 0.1 N hydrochloric acid, the resulting solution is dextrorotatory.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture of alcohol and 0.40% ammonium acetate solution (17:3). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Pseudoephedrine Hydrochloride RS in 0.01 N hydrochloric acid to obtain a solution having a known concentration of about 1.2 mg per mL.
Assay preparation—
Transfer an accurately measured volume of Oral Solution, equivalent to about 60 mg of pseudoephedrine hydrochloride, to a 50-mL volumetric flask, dilute with 0.01 N hydrochloric acid to volume, mix, and filter.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains packing L3. The flow rate is about 1.5 mL per minute. Chromatograph five replicate injections of the
Standard preparation, and record the peak responses as directed for
Procedure: the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 10 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of pseudoephedrine hydrochloride (C
10H
15NO·HCl) in each mL of the Oral Solution taken by the formula:
50(C/V)(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Pseudoephedrine Hydrochloride RS in the
Standard preparation; V is the volume, in mL, of Oral Solution taken; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
Pseudoephedrine Hydrochloride Syrup