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 ,Standard preparation,System suitability solution,and Chromatographic system—Proceed as directed in the Assay for chlorpheniramine maleateunder Chlorpheniramine Maleate and Phenylpropanolamine Hydrochloride Extended-Release Capsules.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 40mg of chlorpheniramine maleate,to a suitable container,add 100mLof water and 10mLof phosphoric acid solution (1in 20),and heat gently until the powder is fully dispersed.Cool to room temperature,and transfer an accurately measured volume of this solution,equivalent to about 0.8mg of chlorpheniramine maleate,to a 100-mLvolumetric flask.Dilute with water to volume,mix,and filter.Quantitatively dilute a portion of this solution,if necessary,with phosphoric acid solution (1in 1000)to obtain a solution having a concentration of about 8µg of chlorpheniramine maleate per mL.

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 Tablets 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 maleateunder Chlorpheniramine Maleate and Phenylpropanolamine Hydrochloride Extended-Release Capsules.

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— Proceed as directed in the Assay for phenylpropanolamine hydrochlorideunder Chlorpheniramine Maleate and Phenylpropanolamine Hydrochloride Extended-Release Capsules.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed quantity of the powder,equivalent to about 500mg of phenylpropanolamine hydrochloride,to a suitable container,add 100mLof water and 10mLof phosphoric acid solution (1in 20),and heat gently until the powder is 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 Tablets 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.