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

B: The retention time of the major peak for phenylpropanolamine hydrochloride in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay for phenylpropanolamine hydrochloride.

Medium: water;900mL.

Apparatus 2: 50rpm.

Times: 3,6,and 12hours.

Procedure— Determine the amounts of C16H19ClN2·C4H4O4and C9H13NO·HCl dissolved by employing the methods set forth in the Assay for chlorpheniramine maleateand the Assay for phenylpropanolamine hydrochloride.

Tolerances— The percentages of the labeled amounts of C16H19ClN2·C4H4O4and C9H13NO·HCl dissolved at the specified times conform to Acceptance Table 1.

Mobile phase— Prepare a filtered and degassed mixture of methanol and water (60:40)containing 0.34g of monobasic potassium phosphate,0.05g of triethylamine hydrochloride,0.025g of sodium lauryl sulfate,and 0.1mLof phosphoric acid in each 100mLof solution.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Chlorpheniramine Maleate RSin water to obtain a solution having a known concentration of about 0.8mg per mL.Quantitatively dilute a portion of this solution with phosphoric acid solution (1in 1000)to obtain a solution having a known concentration of about 8µg per mL.

Assay preparation— Transfer not fewer than 10Capsules to a suitable container,add 100mLof water and 10mLof phosphoric acid solution (1in 20),and heat gently until the Capsules are fully dispersed.Cool to room temperature,and transfer an accurately measured volume of the solution,equivalent to about 0.8mg of chlorpheniramine maleate,to a 100-mLvolumetric flask.Dilute with water to volume,mix,and filter.

System suitability solution— Mix 1part of the Standard preparationprepared above with 1part of the Standard preparationprepared as directed in the Assay for phenylpropanolamine hydrochloride.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 214-nm detector and a 4.6-mm ×15-cm column that contains packing L11.The flow rate is about 2mLper minute.Separately inject about 20µLof the System suitability solution,and record the peak responses as directed for Procedure:the resolution,R,between phenylpropanolamine and chlorpheniramine is not less than 2.0.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the tailing factor for the phenylpropanolamine peak is not greater than 2.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the chlorpheniramine peaks.Calculate the quantity,in mg,of chlorpheniramine maleate (C16H19ClN2·C4H4O4)in the portion of Capsules taken by the formula: in which Cis the concentration,in µg per mL,of USP Chlorpheniramine Maleate RSin the Standard preparation;and rUand rSare the chlorpheniramine peak responses obtained from the Assay preparationand the Standard preparation,respectively.

Mobile phase and Chromatographic system—Proceed as directed in the Assay for chlorpheniramine maleate.

Standard preparation— Dissolve an accurately weighed quantity of USP Phenylpropanolamine Hydrochloride RSin water to obtain a solution having a known concentration of about 2.5mg per mL.Transfer 1.0mLof this solution to a 50-mLvolumetric flask,add 5mLof methanol,dilute with phosphoric acid solution (1in 1000)to volume,and mix.

System suitability solution— Mix 1part of the Standard preparationprepared above with 1part of the Standard preparationprepared as directed in the Assay for chlorpheniramine maleate.

Assay preparation— Transfer not fewer than 10Capsules to a suitable container,add 100mLof water and 10mLof phosphoric acid solution (1in 20),and heat gently until the Capsules are fully dispersed.Cool to room temperature,and transfer an accurately measured volume of the solution,equivalent to about 5mg of phenylpropanolamine hydrochloride,to a 100-mLvolumetric flask.Dilute with water to volume,mix,and filter.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the phenylpropanolamine peaks.Calculate the quantity,in mg,of phenylpropanolamine hydrochloride (C9H13NO·HCl)in the portion of Capsules taken by the formula: in which Cis the concentration,in mg per mL,of USP Phenylpropanolamine Hydrochloride RSin the Standard preparation;and rUand rSare the phenylpropanolamine peak responses obtained from the Assay preparationand the Standard preparation,respectively.