0.005M Octane sulfonic acid— Transfer 1.08g of sodium 1-octane sulfonate to a 1-liter volumetric flask.Dilute with 1.5%(v/v)acetic acid solution to volume,add 5.0mLof triethylamine,mix,and filter.

Mobile phase— Prepare a filtered and degassed mixture of 0.005M Octane sulfonic acidand acetonitrile (39:11).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

System suitability solution— Dissolve suitable quantities of phenylethyl alcohol and USP Pheniramine Maleate RSin water to obtain a solution containing about 3.6and 0.24mg per mL,respectively.

Test solution— Transfer about 24mg of Pheniramine Maleate,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 265-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.5phenylethyl alcohol and 1.0for pheniramine maleate,and the resolution,R,between phenylethyl alcohol and pheniramine maleate is not less than 2.0,the tailing factor is not more than 2.5,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Inject a volume (about 10µL)of the Test solutioninto the chromatograph,record the chromatogram,and measure the peak responses.Calculate the percentage of each impurity (not including the solvent peak and maleic acid,if observed)in the portion of Pheniramine Maleate taken by the formula: in which riis the peak response for each impurity,and rsis the sum of the responses of all of the peaks:not more than 0.5%of any individual impurity is found,and not more than 2.0%of total impurities is found.