Weigh and
powder 20 tablets. Carry out the method for liquid chromatography, using the
following solutions.
Solution preparation:
Solution A
: 2 mg/ml of diisopropylamine in methanol
Solution B
: 5 mg/ml of ammonium acetate
Mobile phase :
Solution A and Solution B (7:3)
Diluent :
Methanol and methylene chloride (1:1)
Internal
standard solution:
5 mg/ml of Terconazole
RS in Diluent.
Standard
solution: Transfer 20
mg of Ketoconazole
RS to a 50-ml volumetric flask. Add 5.0 ml of Internal standard
solution, and dilute with Diluent.
Sample
stock solution: Weigh
and finely powder NLT 20 Tablets. Weigh equivalent to 200 mg of ketoconazole, and transfer to a suitable
screw-capped bottle. Add 50.0 ml of Diluent, shake by mechanical means for 30
min, and centrifuge.
Sample
solution: Transfer 5.0
ml of the clear supernatant so obtained to a 50-ml volumetric flask. Add 5.0 ml
of Internal standard solution, and dilute with Diluent to volume.
Chromatographic
system:
Mode : LC
Detector : UV 225 nm
Column : 3.9-mm × 30-cm; packing L1
Flow rate :
3 ml/min
Injection size : 20 µL
System suitability:
Sample: Standard
solution
[Note—The
relative retention times for and terconazole are 0.6 and 1.0, respectively.]
Suitability requirements:
Resolution: NLT 2.0 between ketoconazole and
terconazole.
Relative standard deviation: NMT 2.0%
Procedure: Inject
the blank (one time), standard solution (six times) and test solution (two
times) in the chromatograph.
The relative
standard deviation of six replicate standards should not be more than 2 %.
Analysis
Samples: Standard solution and
Sample solution.
Calculate the
percentage of C26H28Cl2N4O4 in the portion of Tablets taken:
Result = (RU/RS) × (CS/CU) × 100
|
RU
|
= Ratio of peak responses of ketoconazole to those of terconazole from
the Sample solution
|
|
|
RS
|
= Ratio of peak responses of ketoconazole
to those of terconazole from the Standard solution
|
|
|
CS
|
= Concentration of USP
Ketoconazole RS in the Standard solution (mg/ml)
|
|
|
CU
|
= Nominal concentration of Ketoconazole
in the Sample solution (mg/ml)
|
