Identification—
A:
The UV absorption spectrum of the Test preparation, obtained as directed in the test for Content uniformity, exhibits maxima and minima at the same wavelengths as that of the Standard preparation, concomitantly measured.
B:
To 1 Tablet contained in a 15-mL tube add 4 mL of pyridine and 2 mL of acetic anhydride: an immediate yellow color is produced on shaking. Then heat gently on a steam bath: a rose-pink to a deep red color develops, indicating the presence of citrate ion.
Dissolution 
711
—
Medium:
0.02 N hydrochloric acid; 1000 mL.
Apparatus 1:
100 rpm.
Time:
30 minutes.
Procedure—
Determine the amount of tamoxifen (C
26H
29NO) dissolved from UV absorbances at the wavelength of maximum absorbance at about 275 nm of filtered portions of the solution under test, suitably diluted with
Medium, if necessary, in comparison with a Standard solution having a known concentration of
USP Tamoxifen Citrate RS in the same
Medium.
Tolerances—
Not less than 75% (Q) of the labeled amount of C26H29NO is dissolved in 30 minutes.
Assay—
Mobile phase—
Prepare a methanol solution containing, in each liter, 320 mL of water, 2 mL of glacial acetic acid, and 1.08 g of sodium 1-octanesulfonate.
Standard preparation—
Dissolve a suitable quantity, accurately weighed, of
USP Tamoxifen Citrate RS in
Mobile phase to obtain a solution having a known concentration of about 200 µg per mL.
Assay preparation—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 20 mg of tamoxifen, to a stoppered, 50-mL centrifuge tube. Pipet 30 mL of Mobile phase into the tube, and shake by mechanical means for not less than 15 minutes. Centrifuge at about 1000 rpm, pipet 5 mL of the clear supernatant into a 25-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm column that contains packing L11. The flow rate is about 1.5 mL per minute. Chromatograph the
Standard preparation, and record the peak areas as directed for
Procedure: the relative standard deviation for replicate injections is not more than 3.0%.
Procedure—
Separately inject equal volumes (about 25 µL) of the
Assay preparation and the
Standard preparation into the chromatograph by means of a suitable sampling valve, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in mg, of tamoxifen (C
26H
29NO) in the portion of Tablets taken by the formula:
0.15C(371.51 / 563.64)(rU / rS),
in which 371.51 and 563.64 are the molecular weights of tamoxifen and tamoxifen citrate, respectively;
C is the concentration, in µg per mL, of
USP Tamoxifen Citrate RS in the
Standard preparation; and
rU and
rS are the peak areas obtained from the
Assay preparation and the
Standard preparation, respectively.
