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

Medium: 0.1 N hydrochloric acid; 1000 mL.

Apparatus 1: 100 rpm.

Time: 15 minutes.

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

Standard solution— Prepare a solution of USP Fluoxetine Hydrochloride RS in Medium having a known concentration similar to that of the solution under test.

Test solution— Filter 20 mL of the solution under test.

Chromatographic system (see Chromatography 621)— 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 1.0 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between fluoxetine and ,, -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 20 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the amount of C17H18F3NO dissolved by the formula: in which 309.33 and 345.79 are the molecular weights of fluoxetine and fluoxetine hydrochloride, respectively; C is the concentration, in mg per mL, of USP Fluoxetine Hydrochloride RS in the Standard solution; and rU and rS are the peak responses obtained from the Test solution and the Standard solution, respectively.

Tolerances— Not less than 80% (Q) of the labeled amount of C17H18F3NO is dissolved in 15 minutes.

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

Mobile phase— Prepare a filtered and degassed mixture of Ion-pair solution and acetonitrile (57:43). Make adjustments if necessary (see System Suitability under Chromatography 621).

Resolution solution— Transfer 1 mL of USP Fluoxetine Related Compound B RS and about 13.5 mg of USP Fluoxetine Hydrochloride RS to a 100-mL volumetric flask. Add 2 mL of a solution prepared by dissolving about 22 mg of USP Fluoxetine Hydrochloride RS in 10 mL of 1 N sulfuric acid, heating at about 85 for 3 hours, and cooling to room temperature. Dilute with Mobile phase to volume, and mix. Pipet 10.0 mL of this solution into a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.

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

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

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

Chromatographic system (see Chromatography 621)— 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 1.0 mL per 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 0.19 for -[2-(methylamino)ethyl]benzenemethanol, 0.26 for fluoxetine related compound B, and 1.0 for fluoxetine; the resolution, R, between -[2-(methylamino)ethyl]benzenemethanol and fluoxetine related compound B is not less than 4.5; and the signal-to-noise ratio for the Detector sensitivity solution is not less than 10.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into 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 309.33 and 345.79 are the molecular weights of fluoxetine and fluoxetine hydrochloride, respectively; CS is the concentration, in mg per mL, of USP Fluoxetine Hydrochloride RS in the Standard solution; CU is the concentration, in mg per mL, of fluoxetine in the Test solution; ri is the peak response for each impurity obtained from the Test solution; and rS is the peak response for fluoxetine obtained from the Standard solution: not more than 0.25% of any individual impurity is found; and not more than 0.80% of total impurities is found.

(Official January 1, 2007)

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

Mobile phase— Prepare a filtered and degassed mixture of methanol and Ion-pair solution (67:33). Make adjustments if necessary (see System Suitability under Chromatography 621).

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

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

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

Chromatographic system (see Chromatography 621)— 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 1.0 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between fluoxetine and ,,-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 10 µL) of the Standard preparation and the Assay preparation into 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 309.33 and 345.79 are the molecular weights of fluoxetine and fluoxetine hydrochloride, respectively; C is the concentration, in mg per mL, of USP Fluoxetine Hydrochloride RS in the Standard preparation; D is the dilution factor, if performed, used in preparing the Assay preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.