.
test 1
Buffer solution and Mobile phase
Prepare as directed in the Assay.
Standard solution
Quantitatively transfer 1.0 mL of the Standard preparation, prepared as directed in the Assay, into a 100-mL volumetric flask. Dilute with Buffer solution to volume, and mix to obtain a solution having a known concentration of 0.001 mg of fludarabine phosphate per mL.
Test solution
Use the Assay preparation.
Sensitivity solution
Quantitatively transfer 2.0 mL of the Standard solution into a 25-mL volumetric flask. Dilute with Buffer solution to volume, and mix to obtain a solution having a known concentration of 0.08 µg of fludarabine phosphate per mL.
Resolution solution
Add 3 drops of 2 N hydrochloric acid solution to 1.5 mL of the
Standard solution. Mix well, and heat at 80

for 30 minutes.
Chromatographic system (see Chromatography
621
)
The liquid chromatograph is equipped with a 260-nm UV detector and a 4.6-mm × 25-cm column containing 5-µm packing L1. The flow rate is 1.0 mL per minute. Chromatograph the
Sensitivity solution at 260 nm. The ratio of the fludarabine phosphate peak height to the noise height is not less than 10, the noise height being determined by a suitable procedure. Chromatograph the
Resolution solution, and record the peak responses as directed for
Procedure: the resolution,
R, between the fludarabine phosphate peak and the 2-fluoroadenine peak (relative retention time about 1.3) is not less than 5. Chromatograph the
Standard solution, and record the peak responses as directed for
Procedure: the tailing factor is not more than 1.8 for the fludarabine phosphate peak, and the relative standard deviation for replicate injections is not more than 1%.
Procedure
Separately inject equal volumes (about 20 µL) of the
Standard solution and the
Test solution into the chromatograph, and record the chromatograms at 260 nm. Measure the response of the fludarabine phosphate peak for the
Standard solution, and measure the responses of all the major peaks, excluding the fludarabine phosphate peak, for the
Test solution. Calculate the percentage of each impurity present in the portion of Injection taken by the formula:
1000(C/F)(rU / rS)
in which
C is the concentration, in mg per mL, of
USP Fludarabine Phosphate RS in the
Standard solution; F is a relative response factor (see
Table 1 for values) and equal to 1.0 for any other impurities;
rU is the peak response for each individual impurity in the
Test solution; and
rS is the peak response for fludarabine phosphate in the
Standard solution. The limits of impurities are specified in
Table 1.
Table 1
Impurity |
Relative Response Factor (F) |
Relative Retention Time |
Limit (w/w, %) |
Iso-ara-guanine monophosphate |
0.28 |
0.45 |
0.4 |
2-Amino analog |
0.45 |
0.54 |
0.2 |
Compound A |
1.0 |
0.62 |
0.3 |
2-Fluoroadenine |
1.0 |
1.3 |
0.2 |
Individual unspecified impurity |
1.0 |
|
0.3 |
Total impurities |
|
|
2.0 |