A: The retention time of the major peak for dexbrompheniramine maleate in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

B: The retention time of the major peak for pseudoephedrine sulfate in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

C: A solution of it responds to the test for Sulfate 191.

D: Transfer a volume of Oral Solution, equivalent to about 6 mg of dexbrompheniramine maleate, to a separatory funnel, add 0.5 mL of ammonium hydroxide and 5 mL of methylene chloride, shake for 1 minute, and allow the layers to separate. Use the clear, lower layer as the test solution. Prepare a Standard solution in methanol containing 1.2 mg of USP Dexbrompheniramine Maleate RS and a second Standard solution in methanol containing 9 mg of USP Pseudoephedrine Sulfate RS per mL. Separately apply 5 µL of the test solution and each Standard solution to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of ethyl ether, methanol, and ammonium hydroxide (16:3:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by examination under short-wavelength UV light: the RF values of the two principal spots obtained from the test solution correspond to those obtained from the respective Standard solutions.

for oral solution packaged in single-unit containers: meets the requirements.

for oral solution packaged in multiple-unit containers: meets the requirements.

Mobile phase— Prepare a mixture of water, acetonitrile, methanol, and tetrahydrofuran (55:32:8:5). Transfer 0.1 mL of phosphoric acid, followed by 0.433 g of sodium lauryl sulfate, to each 100 mL of this mixture, and mix. Adjust with ammonium hydroxide to a pH of 3.50 ± 0.05, filter, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621). [note—The pH of the Mobile phase is critical, and may cause differences of 1 to 4 minutes in the retention times of the internal standard and dexbrompheniramine.]

Internal standard solution— Dissolve an accurately weighed quantity of naphazoline hydrochloride in Mobile phase to obtain a solution containing 0.5 mg per mL.

Dexbrompheniramine standard solution— Dissolve an accurately weighed quantity of USP Dexbrompheniramine Maleate RS in Mobile phase to obtain a solution having a known concentration of about 6000J µg per mL, J being the ratio of the labeled amount, in mg, of dexbrompheniramine maleate to the labeled amount, in mg, of pseudoephedrine sulfate per mL of the Oral Solution.

Standard preparation— Transfer about 30 mg of USP Pseudoephedrine Sulfate RS, accurately weighed, to a 25-mL volumetric flask, add 5.0 mL each of Dexbrompheniramine standard solution and Internal standard solution, dilute with Mobile phase to volume, and mix to obtain a Standard preparation having known concentrations of about 1.2J mg of USP Dexbrompheniramine Maleate RS per mL and about 1.2 mg of USP Pseudoephedrine Sulfate RS per mL.

Assay preparation— Using a “to contain” pipet, transfer an accurately measured volume of Oral Solution, equivalent to about 30 mg of pseudoephedrine sulfate, to a 25-mL volumetric flask. Rinse the pipet with about 5 mL of Mobile phase, collecting the rinsing in the volumetric flask. Add 5.0 mL of Internal standard solution, dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm column that contains packing L11. The flow rate is about 1.5 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative retention times are about 1.0 for pseudoephedrine, 1.5 for naphazoline, and 2.5 for dexbrompheniramine; the resolution, R, between the pseudoephedrine and naphazoline peaks is not less than 3; the resolution, R, between the dexbrompheniramine and naphazoline peaks is not less than 3; 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 quantities, in mg per mL, of dexbrompheniramine maleate (C10H15BrN2·C4H4O4) and pseudoephedrine sulfate [(C10H15NO)2·H2SO4] in the portion of Oral Solution taken by the formula: in which C is the concentration, in mg per mL, of the appropriate USP Reference Standard in the Standard preparation; V is the volume, in mL, of Oral Solution taken; and RU and RS are the ratios of the peak responses of the corresponding analyte to the internal standard obtained from the Assay preparation and the Standard preparation, respectively.