Procedure:
Solution A: A solution containing 4.4
mg/mL of dibasic potassium phosphate and 0.5 mg/mL of sodium 1-octanesulfonate,
adjusted with phosphoric acid to a pH of 8.20 (± 0.05)
Mobile phase: Acetonitrile, methanol, and
Solution A (9:3:8)
Solution B:
1.7 mg/mL of monobasic ammonium phosphate, adjusted with ammonium hydroxide to
a pH of 10.00 ± 0.05
Diluent A: Methanol, acetonitrile, and
Solution B (7:6:7)
Standard solution: Dissolve Azithromycin RS
in Diluent A using about 75% of the final volume, sonicate to dissolve, dilute
with Diluent A to volume, and mix to obtain a solution having a known
concentration of 0.4 mg/mL of azithromycin.
System suitability stock solution: 0.2 mg/mL of Azaerythromycin A RS in acetonitrile. [Note—Sonicate if necessary to dissolve.
]
System suitability solution: 0.02 mg/mL of azaerythromycin
A from System suitability stock solution and 0.02 mg/mL of azithromycin from
Standard solution in Diluent A
Sample stock solution: Weigh and finely powder NLT 20
Tablets. Transfer an equivalent to 667 mg of azithromycin to a 200-mL
volumetric flask. Add 75 mL of Diluent A, and sonicate for NLT 15 min. Shake by
mechanical means for NLT 15 min. Allow the solution to equilibrate to room
temperature, dilute with Diluent A to volume, and mix.
Sample solution:
0.4 mg/mL of azithromycin from Sample stock solution in Diluent A. Pass through
a filter having a porosity of 0.45-µm.
Chromatographic system
Mode: LC
Detector: UV 210 nm
Column: 4.6-mm × 25-cm column; 5-µm
packing L1
Temperature: 50
Flow rate: 1.5 mL/min
Injection size: 50 µL
System suitability
Samples:
System suitability solution and Standard solution
[Note—Identify the
peaks by their relative retention times, which are 0.64 and 1.0 for
azaerythromycin A and azithromycin, respectively. ]
Suitability requirements
Resolution: NLT 2.5 between azaerythromycin
A and azithromycin, System suitability solution
Column efficiency: NLT 1000 theoretical plates,
Standard solution
Tailing factor: NMT 2.0, Standard solution
Relative standard deviation: NMT 2.0%, Standard solution
Analysis
Samples: Standard
solution and Sample solution
Calculate the
percentage of C38H72N2O12 in the portion of Azithromycin Tablets taken:
Result = (rU/rS) × (CS/CU) × P × F × 100
|
rU
|
=
|
response of azithromycin from the
Sample solution
|
|
rS
|
=
|
response of azithromycin from the
Standard solution
|
|
CS
|
=
|
concentration of Azithromycin
RS in the Standard solution (mg/mL)
|
|
CU
|
=
|
nominal concentration of
azithromycin in the Sample solution (mg/mL)
|
|
P
|
=
|
potency of Azithromycin RS
(µg/mg)
|
|
F
|
=
|
unit conversion factor, 0.001
mg/µg
|
Acceptance criteria: 90.0%–110.0%
