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A: Infrared Absorption á197Sñ—

B: Dissolve 0.25g of Propoxyphene Hydrochloride in 15mLof Purified Water,and treat 3mLof this solution with 1mLof 6Nammonium hydroxide to precipitate the propoxyphene base.Filter to remove the precipitate,acidify the filtrate with 2mLof nitric acid,and add 1mLof silver nitrate TS:a white,curdy precipitate that is soluble in an excess of 6Nammonium hydroxide confirms the presence of silver chloride.USP28

Test solution: 10mg per mL,in water,freshly prepared.

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Mobile phaseand Chromatographic system— Proceed as directed in theAssay.

Standard stockUSP28solution— Accurately weighUSP28about 10mg each of USP Propoxyphene Related Compound A RSand USP Propoxyphene Related Compound B RSintoUSP28a 50-mLvolumetric flask,dissolve using 2mLof methanol,USP28dilute with Mobile phaseto volume,and mix.

Standard solution— Transfer 5.0mLof the Standard stock solutionto a 50-mLvolumetric flask,dilute with Mobile phase to volume,and mix.USP28

Test solution— Use theAssay preparation.

System suitability solution— Transfer 1.0mLof the Standard stock solutionto a 10.0-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.USP28

Chromatographic system— Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.63for propoxyphene related compound A,0.78for propoxyphene related compound B,USP28and 1.0for propoxyphene hydrochloride;the resolution,R,between propoxyphene related compound BUSP28and propoxyphene related compound AUSP28is not less than 2.0;USP28and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— SeparatelyUSP28inject equalUSP28volumes (about 50µL)of the Test solution and the Standard solutionUSP28into the chromatograph,record the chromatograms,and measure the peak responses.Calculate the quantity,in mg,USP28of propoxyphene related compound Ain the portion of Propoxyphene Hydrochloride taken by the formula: in which Cis the concentration,in mg per mL,of USP Propoxyphene Related Compound A RSin the Standard solution;and rUand rSare the propoxyphene related compound Apeak responses obtained from the Test solutionand Standard solution,respectively.USP28Not more than 0.5%of propoxyphene related compound AUSP28is found.Calculate the quantity,in mg,USP28of propoxyphene related compound Bas theUSP28hydrochloride in the portion of Propoxyphene Hydrochloride taken by the formula: in which Cis the concentration,in mg per mL,of USP Propoxyphene Related Compound B RSin the Standard solution;361.93and 325.45are the molecular weights of propoxyphene related compound Bas the hydrochloride and propoxyphene related compound B,respectively;and rUand rSare the propoxyphene related compound Bpeak responses obtained from the Test solutionand the Standard solution,respectively.USP28Not more than 0.6%of propoxyphene related compound Bas theUSP28hydrochloride is found.

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0.1MUSP28Monobasic ammonium phosphate buffer,pH6.3— Dissolve 11.5g of monobasic ammonium phosphate and 1.0mLof triethylamine in 1000mLof water,adjust with 10%sodium hydroxide to a pHof 6.3±0.05,and mix.

Mobile phase— Prepare a filtered and degassed mixture of methanol and 0.1MUSP28Monobasic ammonium phosphate buffer,pH6.3(67:33).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Propoxyphene Hydrochloride RSinMobile phase to obtain a solution having a known concentration of about 5.0mg per mL.

Assay preparation— Transfer about 250mg of Propoxyphene Hydrochloride,accurately weighed,to a 50-mLvolumetric flask,dissolve in and dilute withMobile phase to volume,and mix.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the retention time of propoxyphene hydrochloride is about 9minutes;the tailing factor for the propoxyphene hydrochloride peak is not more than 3.5;USP28and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 50µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C22H29NO2·HCl in the portion of Propoxyphene Hydrochloride taken by the formula: in which Cis the concentration,in mg per mL,of USP Propoxyphene Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.