Test 1: If the product complies with this test,the labeling indicates that it meets USPDrug Release Test 1.

Medium: water;1000mL.

Apparatus 1: 100rpm.

Times: 3hours,6hours,12hours.

Solvent A— Dissolve 1.9g of sodium 1-hexanesulfonate in 700mLof water,add 50mLof 1Mmonobasic sodium phosphate and 20mLof 0.25Ntriethylammonium phosphate (prepared by mixing 500mLof a solution containing 25.3g of triethylamine and 500mLof a solution containing 9.6g of phosphoric acid),and mix.Dilute with water to 1liter,and mix.

Mobile phase— Prepare a filtered and degassed mixture of Solvent Aand methanol (100:82).Make adjustments if necessary (see Chromatography á621ñ).

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 210-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 1.5mLper minute.Chromatograph replicate injections of a Standard solution,and record the peak responses as directed for Procedure:the tailing factor for the analyte peak is not more than 1.5,and the relative standard deviation for replicate injections is not more than 2%.

Procedure— Inject an accurately measured volume (about 50µL)of a filtered portion of the solution under test into the chromatograph,record the chromatogram,and measure the response for the major peak.Calculate the quantity of C9H13NO·HCl dissolved by comparison with a Standard solution having a known concentration of USP Phenylpropanolamine Hydrochloride RSin the same medium and similarly chromatographed.

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

Mobile phase— [NOTE—Prepare the Mobile phase one day prior to use.]Prepare a filtered and degassed mixture of water,methanol,10%tetramethylammonium hydroxide,and phosphoric acid (700:300:14:3.5).Make adjustments if necessary (see Chromatography á621ñ).

Internal standard solution— Prepare a solution of Theophylline in methanol having a final concentration of about 0.1mg per mL.

Standard preparation— Prepare a solution of USP Phenylpropanolamine Hydrochloride RSin Internal standard solutionhaving an accurately known concentration of 3mg per mL.

Assay preparation— Transfer the accurately weighed contents of a counted number of Capsules,equivalent to about 750mg of phenylpropanolamine hydrochloride,to a container.Add 250.0mLof Internal standard solution,mix,sonicate for 30minutes,allow to stand overnight,and filter.

Chromatographic system (see Chromatography á621ñ)—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 1.5mLper minute.Chromatograph replicate injections of the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 2.0%,and the resolution,R,between phenylpropanolamine and theophylline is not less than 5.0.

Procedure— Separately inject equal volumes (about 5µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.The relative retention times are about 0.6for phenylpropanolamineand 1.0for theophylline.Calculate the quantity,in mg,of C9H13NO·HCl in each of the Capsules taken by the formula: in which Cis the concentration,in mg per mL,of USP Phenylpropanolamine Hydrochloride RSin the Standard preparation,Nis the number of Capsules taken,and RUand RSare the peak response ratios obtained from the Assay preparationand the Standard preparation,respectively.