A: Infrared Absorption á197Kñ:previously dried at 105for 3hours.

B: Ultraviolet Absorption á197Uñ—

Test solution: 10mg per mL,in chloroform.

Change to read:

Mobile phaseand Chromatographic system— Proceed as directed in theAssay.

Standard stockUSP28solution— Accurately weighUSP28about 10mg each of USP Propoxyphene Related Compound A RSand USPa-d-2-Acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane RSintoUSP28a 50-mLvolumetric flask,dissolve using 2mLof methanol,USP28dilute withMobile phase to volume,and mix.

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

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

Test solution— Use theAssay preparation.

Chromatographic system— Chromatograph theSystem suitability solution,and record the peak responses as directed forProcedure:the relative retention times are about 0.63for propoxyphene related compound A,0.78for a-d-2-acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane,and 1.0for propoxyphene napsylate;the resolution,R,between a-d-2-acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane and propoxyphene related compound AUSP28is not less than 2.0;USP28and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 50µL)of the Standard solutionand theUSP28Test solution into the chromatograph,record the chromatograms,and measure the peak responses.Calculate the quantity,in mg,USP28of propoxyphene related compound AUSP28in the portion of Propoxyphene Napsylate taken by the formula: in which Cis the concentration,in mg per mL,of USP Propoxyphene Related Compound A RSin the Standard solution;491.67and 319.88are the molecular weights of propoxyphene related compound Anapsylate and propoxyphene related compound A,respectively;and rUand rSare the propoxyphene related compound Apeak responses obtained from the Test solutionand the Standard solution,respectively:not more than 0.5%of propoxyphene related compound Anapsylate is found.USP28Calculate the quantity,in mg,USP28of a-d-2-acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane napsylate in the portion of Propoxyphene Napsylate taken by the formula: in which Cis the concentration,in mg per mL,of USPa-d-2-Acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane RSin the Standard solution;533.71and 325.45are the molecular weights of a-d-2-acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane napsylate and a-d-2-acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane,respectively;and rUand rSare the a-d-2-acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane peak responses obtained from the Test solutionand the Standard solution,respectively.USP28Not more than 0.6%of a-d-2-acetoxy-4-dimethylamino-1,2-diphenyl-3-methylbutane napsylate is found.

Solvent— Use dimethyl sulfoxide.

Change to read:

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 (seeSystem Suitability underChromatography á621ñ).

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

Assay preparation— Transfer about 250mg of Propoxyphene Napsylate,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 theStandard preparation,and record the peak responses as directed forProcedure:the retention time of propoxyphene napsylate is about 9minutes;the tailing factor for the propoxyphene napsylate 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·C10H8O3Sin the portion of Propoxyphene Napsylate taken by the formula: in whichCis the concentration,in mg per mL,of USP Propoxyphene Napsylate RSin theStandard preparation;andrUandrSare the peak responses obtained from theAssay preparation and theStandard preparation,respectively.