Identification—
Dissolve a suitable quantity in water to obtain a solution having a concentration of about 60 µg per mL, and centrifuge, if necessary: the UV absorption spectrum of the solution so obtained exhibits maxima and minima at the same wavelengths as that of a similar solution of
USP Phenylephrine Hydrochloride RS, concomitantly measured.
Assay—
Mobile phase—
Prepare a mixture of methanol and water (1:1) containing 1.1 g of sodium 1-octanesulfonate per liter, adjust with phosphoric acid to a pH of 3.0, filter, and degas. Make adjustments to the methanol and water ratio, if necessary (see
System Suitability under
Chromatography 
621
).
Dilution solvent—
Prepare a mixture of methanol and water (1:1), and adjust with phosphoric acid to a pH of 3.0.
Standard preparation—
Dissolve an accurately weighed quantity of
USP Phenylephrine Hydrochloride RS in
Dilution solvent to obtain a Stock standard solution having a known concentration of about 2 mg per mL. Dilute an accurately measured volume of this solution with
Dilution solvent to obtain the
Standard preparation having a known concentration of about 0.1 mg per mL.
Assay preparation—
Transfer an accurately weighed amount of Nasal Jelly, equivalent to about 10 mg of phenylephrine hydrochloride, to a 100-mL volumetric flask. Dilute with Dilution solvent to volume, and mix.
Resolution solution—
Transfer 5.0 mL of Stock standard solution to a 100-mL volumetric flask, add 10 mg of
USP Epinephrine Bitartrate RS, dilute with
Dilution solvent to volume, and mix.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 280-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the
Resolution solution: the resolution,
R, is not less than 1.5, and the tailing factor for the phenylephrine peak is not more than 2.0. Chromatograph replicate injections of the
Standard preparation: the relative standard deviation is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 20 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 C
9H
13NO
2·HCl in the portion of Nasal Jelly taken by the formula:
100C(rU / rS)
in which
C is the concentration, in mg per mL, of
USP Phenylephrine Hydrochloride RS in the
Standard preparation, and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
