Identification—
A:
Ultraviolet Absorption 
197U
—
Medium:
methanol and water (75:25).
Solution:
15 µg per mL. Obtain the test solution as follows. Mix a volume of Injection, equivalent to 20 mg of zidovudine, with 50 mL of Medium in a 200-mL volumetric flask, and dilute with Medium to volume. Dilute the resulting solution 15 in 100 with Medium, and mix.
B:
The retention time of the major peak in the chromatogram of the
Assay preparation corresponds to that of the
Standard preparation, as obtained in the
Assay.
Related compounds—
Mobile phase
,
Standard stock solution,
Zidovudine related compound C standard stock solution, and
Chromatographic system—Proceed as directed in the
Assay under
Zidovudine.
Standard solution—
Transfer 10.0 mL of Standard stock solution and 1.0 mL of Zidovudine related compound C standard stock solution to a 100-mL volumetric flask, add 25 mL of water, mix, dilute with methanol to volume, and mix.
Test solution—
Proceed as directed for
Assay preparation in the
Assay.
Procedure—
Separately inject equal volumes (about 10 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the quantity, in mg, of zidovudine related compound C (thymine) in the volume of Injection taken by the formula:
1000C [(rU / rS) / Q],
in which
C is the concentration, in mg per mL, of
USP Zidovudine Related Compound C RS in the
Standard solution;
rU and
rS are the peak responses of zidovudine related compound C (thymine) obtained from the
Test solution and the
Standard solution, respectively; and
Q is the quantity, in mg, of zidovudine in the volume of Injection taken, as determined in the
Assay: not more than 1.0% is found.
Assay—
Mobile phase
,
Standard stock solution,
Zidovudine related compound C standard stock solution, and
Chromatographic system—Proceed as directed in the
Assay under
Zidovudine.
Standard preparation—
Transfer 10.0 mL of Standard stock solution and 2.0 mL of Zidovudine related compound C standard stock solution to a 100-mL volumetric flask, add 25 mL of water, mix, dilute with methanol to volume, and mix.
Assay preparation—
Transfer an accurately measured volume of Injection, equivalent to about 25 mg of zidovudine, to a 250-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.
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 zidovudine (C
10H
13N
5O
4) in the volume of Injection taken by the formula:
1000C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Zidovudine RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
