Test specimen— Transfer 1Tablet to a suitable container,dissolve in 10mLof chloroform,and filter.Rinse the container with 5mLof chloroform,and filter.Evaporate the combined filtrate in a hood with the aid of a current of air and mild heat to dryness.

Medium: 0.1Nhydrochloric acid;1000mL.

Apparatus 1: 100rpm.

Time: 15minutes.

Ion-pair solution,Mobile phase,and System suitability solution— Prepare as directed in the Assay.

Standard solution— Prepare a solution of USP Fluoxetine Hydrochloride RSin Mediumhaving a known concentration similar to that of the solution under test.

Test solution— Filter 20mLof the solution under test.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 227-nm detector and a 4.6-mm ×7.5-cm column that contains 3.5-µm packing L7.The column temperature is maintained at 38.The flow rate is about 1.0mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the resolution,R,between fluoxetine and a,a,a-trifluoro-p-cresol is not less than 2.0;the tailing factor for the fluoxetine peak is not more than 1.7;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the amount of C17H18F3NOdissolved by the formula: in which 309.33and 345.79are the molecular weights of fluoxetine and fluoxetine hydrochloride,respectively;Cis the concentration,in mg per mL,of USP Fluoxetine Hydrochloride RSin the Standard solution;and rUand rSare the peak responses obtained from the Test solutionand the Standard solution,respectively.

Tolerances— Not less than 80%(Q)of the labeled amount of C17H18F3NOis dissolved in 15minutes.

Ion-pair solution— Dissolve 6.5g of sodium 1-octanesulfonate in 1000mLof water,add 2.9mLof phosphoric acid,and adjust with a sodium hydroxide solution (1in 5)to a pHof 3.0.

Mobile phase— Prepare a filtered and degassed mixture of Ion-pair solutionand acetonitrile (57:43).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Resolution solution— Transfer 1mLof USP Fluoxetine Related Compound B RSand about 13.5mg of USP Fluoxetine Hydrochloride RSto a 100-mLvolumetric flask.Add 2mLof a solution prepared by dissolving about 22mg of USP Fluoxetine Hydrochloride RSin 10mLof 1Nsulfuric acid,heating at about 85for 3hours,and cooling to room temperature.Dilute with Mobile phaseto volume,and mix.Pipet 10.0mLof this solution into a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Detector sensitivity solution— Prepare a solution of Resolution solutionin Mobile phase(1in 100).

Standard solution— Dissolve an accurately weighed quantity of USP Fluoxetine Hydrochloride RSin Mobile phase,and dilute quantitatively,and stepwise if necessary,to obtain a solution having a known concentration of about 0.0135mg per mL.

Test solution— Place 10Tablets in a volumetric flask of suitable size.Dissolve in and dilute with Mobile phaseto volume to obtain a solution having a concentration of about 2mg of fluoxetine per mL.Pass a portion of the solution through a suitable filter,and use the filtrate.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 215-nm detector and a 4.6-mm ×15-cm column that contains 3.5-µm packing L7.The column temperature is maintained at 30.The flow rate is about 1.0mLper minute.Chromatograph in the following order the Mobile phase,the Detector sensitivity solution,and the Resolution solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.19for a-[2-(methylamino)ethyl]benzenemethanol,0.26for fluoxetine related compound B,and 1.0for fluoxetine;the resolution,R,between a-[2-(methylamino)ethyl]benzenemethanol and fluoxetine related compound Bis not less than 4.5;and the signal-to-noise ratio for the Detector sensitivity solutionis not less than 10.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms for a period of time equal to three times the retention time of the main peak,and measure the areas for all the peaks.Calculate the percentage of each impurity in the portion of Tablets taken by the formula: in which 309.33and 345.79are the molecular weights of fluoxetine and fluoxetine hydrochloride,respectively;CSis the concentration,in mg per mL,of USP Fluoxetine Hydrochloride RSin the Standard solution;CUis the concentration,in mg per mL,of fluoxetine in the Test solution;riis the peak response for each impurity obtained from the Test solution;and rSis the peak response for fluoxetine obtained from the Standard solution:not more than 0.2%of any individual impurity is found;and not more than 0.8%of total impurities is found.

Ion-pair solution— Dissolve 7.1g of sodium 1-pentanesulfonate in 1000mLof water,add 2.9mLof glacial acetic acid,and adjust with a sodium hydroxide solution (1in 5)to a pHof 5.0.

Mobile phase— Prepare a filtered and degassed mixture of methanol and Ion-pair solution(67:33).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

System suitability solution— Transfer about 10mg of a,a,a-trifluoro-p-cresol,accurately weighed,to a 50-mLvolumetric flask.Dissolve in and dilute with Mobile phaseto volume,and mix.Pipet 10mLof this solution into a 100-mLvolumetric flask containing about 11mg of USP Fluoxetine Hydrochloride RS,dilute with Mobile phaseto volume,and mix.

Standard preparation— Dissolve an accurately weighed quantity of USP Fluoxetine Hydrochloride RSin Mobile phaseto obtain a solution having a known concentration of about 0.1mg per mL.

Assay preparation— Transfer 10Tablets to a 1000-mLvolumetric flask.Add about 500mLof Mobile phase,and shake to disintegrate the Tablets.Dilute with Mobile phaseto volume,and sonicate for 10minutes.Transfer a portion of this solution to a volumetric flask of suitable size,and dilute quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a concentration of about 0.1mg of fluoxetine per mL.Pass through a suitable filter,and use the filtrate.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 227-nm detector and a 4.6-mm ×7.5-cm column that contains 3.5-µm packing L7.The column temperature is maintained at 38.The flow rate is about 1.0mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the resolution,R,between fluoxetine and a,a,a-trifluoro-p-cresol is not less than 4.0;the tailing factor for the fluoxetine peak is not more than 1.7;and the relative standard deviation for replicate injections is not more than 2.0%.

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 major peaks.Calculate the quantity,in mg,of fluoxetine (C17H18F3NO)in the portion of Tablets taken by the formula: in which 309.33and 345.79are the molecular weights of fluoxetine and fluoxetine hydrochloride,respectively;Cis the concentration,in mg per mL,of USP Fluoxetine Hydrochloride RSin the Standard preparation;Dis the dilution factor,if performed,used in preparing the Assay preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.