A: Infrared Absorption 197K.

B: It meets the requirements of the test for Chloride 191, the sample being dissolved in methanol.

Solution A— Dissolve 9.0 g of monobasic potassium phosphate in 1000 mL of water, and mix. Add 0.6 mL of phosphoric acid, further adjust with phosphoric acid or potassium hydroxide solution to a pH of 3.0 ± 0.1, and mix.

Solution B— Use acetonitrile.

Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography 621).

Diluent— Prepare a mixture of Solution A and acetonitrile (70:30).

System suitability stock solution— Transfer about 6 mg of USP Raloxifene Hydrochloride RS to a 50-mL volumetric flask, and add 15.0 mL of acetonitrile, 3.0 mL of water, and 5.0 mL of 30 percent hydrogen peroxide (unstabilized). Mix, and dissolve the raloxifene hydrochloride. Shake the solution for approximately 30 minutes, followed by approximately 30 minutes of sonication. Let it stand at 30 for at least 6 hours. Dilute with Solution A to 50.0 mL. [note—Raloxifene hydrochloride is partly converted to raloxifene N-oxide under these conditions. The reaction time can be varied as necessary to achieve an appropriate level of raloxifene N-oxide.]

System suitability solution— Transfer about 15 mg of USP Raloxifene Hydrochloride RS to a 50-mL volumetric flask, add 5.0 mL of System suitability stock solution, dilute with Diluent to volume, and mix.

Standard solution— Dissolve an accurately weighed quantity of USP Raloxifene Hydrochloride RS in Diluent, and dilute quantitatively with Diluent to obtain a solution having a known concentration of about 0.003 mg per mL.

Test solution— Transfer about 30 mg of Raloxifene Hydrochloride, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with Diluent to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 280-nm detector and a 4.6-mm × 25-cm column that contains 5-µm base deactivated L7 packing. The temperature is maintained at 35. The flow rate is about 1 mL per minute. The chromatograph is programmed as follows: [note—Adjust the start time of the gradient step based on the instrument's dwell volume.] Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between the raloxifene and raloxifene N-oxide peaks is not less than 3.0; and the tailing factor for the raloxifene peak is not more than 2.0.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms for not less than two times the retention time of the raloxifene peak, and measure all of the peak responses. Calculate the percentage of each impurity in the portion of Raloxifene Hydrochloride taken by the formula: in which CS is the concentration, in mg per mL, of USP Raloxifene Hydrochloride RS in the Standard solution; CU is the concentration, in mg per mL, of Raloxifene Hydrochloride in the Test solution; ri is the peak response of each impurity in the Test solution; and rS is the response of the raloxifene peak in the Standard solution. The limits are as shown in the accompanying table. Disregard any peak that is less than 0.05%.

Buffer solution— Dissolve 7.2 g of monobasic potassium phosphate in 1000 mL of water, and mix. Add 1.5 mL of phosphoric acid, further adjust with phosphoric acid or potassium hydroxide solution to a pH of 2.5 ± 0.1, and mix.

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

System suitability stock solution— Prepare as directed under Related compounds.

Standard preparation— Dissolve an accurately weighed quantity of USP Raloxifene Hydrochloride RS in Mobile phase, and dilute quantitatively to obtain a solution having a known concentration of about 0.05 mg per mL.

Assay preparation— Transfer about 5 mg of Raloxifene Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 280-nm detector and a 4.6-mm × 15-cm column that contains 3.5-µm base deactivated L7 packing. The temperature is maintained at 35. The flow rate is about 1.5 mL per minute. Chromatograph the System suitability stock solution, and record the peak responses as directed for Procedure: the tailing factor for the raloxifene peak is not more than 2.0; the resolution, R, between raloxifene and raloxifene N-oxide is not less than 2.0; and the relative standard deviation for replicate injections calculated for the raloxifene peak is not more than 0.7%.

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 raloxifene peaks. Calculate the percentage of C28H27NO4S·HCl in the portion of Raloxifene Hydrochloride taken by the formula: in which CS is the concentration, in mg per mL, of USP Raloxifene Hydrochloride RS in the Standard preparation; CU is the concentration, in mg per mL, of Raloxifene Hydrochloride in the Assay preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.