A:Infrared Absorption 197K—

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

Medium: water; 900 mL.

Apparatus 2: 50 rpm.

Time: 30 minutes.

Procedure— Determine the amount of C10H13N5O4 dissolved by employing the procedure set forth in the Assay, using a filtered portion of the solution under test as the Assay preparation in comparison with a Standard solution having a known concentration of USP Zidovudine RS in the same Medium.

Tolerances— Not less than 80% (Q) of the labeled amount of C10H13N5O4 is dissolved in 30 minutes.

PROCEDURE FOR CONTENT UNIFORMITY—

Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay.

Test preparation— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Test preparation into the chromatograph, record the chromatograms, and measure all of the peak responses. Calculate the percentage of each impurity in the portion of Tablets taken by the formula: in which F is the relative response factor and is equal to 0.59 for any peak with a relative retention time of 0.17, and is equal to 1.00 for all other peaks; ri is the peak response for each impurity obtained from the Test preparation; and rS is the peak response for zidovudine obtained from the Standard preparation: not more than 1.5% of an impurity with a relative retention time of 0.17 is found; not more than 0.2% of any other impurity is found; and not more than 2.0% of total impurities is found.

(Official January 1, 2007)

Mobile phase— Dissolve 3.0 g of sodium acetate and 1.3 g of sodium 1-octanesulfonate in 900 mL of water. Add 90 mL of methanol and 40 mL of acetonitrile, and mix. Adjust with glacial acetic acid to a pH of 5.3, filter, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Zidovudine RS in a volume of methanol, equivalent to not more than 1.2% of the total flask volume, dilute with water to volume, and mix to obtain a final solution having a known concentration of about 0.12 mg per mL.

Assay preparation— Transfer a counted number of Tablets, equivalent to 1500 mg of zidovudine, to a 500-mL volumetric flask. Add about 50 mL of water, and shake by mechanical means for 30 minutes to disperse the Tablets. Add about 150 mL of methanol, and sonicate for 10 minutes. Dilute with water to volume, and mix. Pipet 4.0 mL into a 100-mL volumetric flask, and dilute with water to volume. Mix, and pass a portion of the solution through a suitable nylon filter, discarding the first 2 mL of the filtrate.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 265-nm detector and a 4.6-mm × 15-cm column that contains packing L1. The flow rate is about 1.3 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the resolution, R, between zidovudine and a peak having a relative retention time of about 1.2 is not less than 2.5; the tailing factor for the zidovudine peak is not more than 2.0; 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 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 zidovudine (C10H13N5O4) in each Tablet taken by the formula: in which C is the concentration, in mg per mL, of USP Zidovudine RS in the Standard preparation; N is the number of Tablets taken for the Assay preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.