 Solution preparation:
|
Buffer: Add 1.4 ml of triethylamine into a 200-ml flask
containing 180 ml of water. Adjust the solution with phosphoric acid to a pH of
3.0 (± 0.1). Dilute with water to volume, and mix well.
|
Mobile phase: Mix 700 ml of Methanol with 300 ml of acetonitrile
and 100 ml of Buffer.
|
Standard stock
solution: Weigh accurately about 34.6 mg of Amlodipine
Besylate WS transfer it into 50 ml volumetric flask add 30 ml mobile phase to
dissolve. And make up volume to 50 ml with mobile phase.
Amlodipine
related compound A stock solution: Weigh
accurately about 2.5 mg of Amlodipine
Related Compound A RS transfer it into 50 ml volumetric flask add 30
ml mobile phase to dissolve. And make up volume to 50 ml with mobile phase.
System
suitability solution: Mix 2 ml of Standard
stock solution and 2 ml of Amlodipine related compound A stock solution in 50
ml volumetric flask make up volume with mobile phase.
Standard solution: Dilute 2 ml of Standard stock solution to 50 ml with mobile
phase.
Test solution: Weigh
and powder 20 tablets. Weigh and transfer the powder, equivalent to
25 mg amlodipine and transfer it into 50 ml volumetric flask. Fill the flask to
20 ml with mobile phase sonicate for 5 min, and shake by mechanical means for
20 min. Dilute with mobile phase to volume, mix, and filter. Further dilute 2
ml of solution to 50 ml with mobile phase.
Chromatographic
system:
Column : 3.9-mm
× 15-cm column; 5-µm packing L1 (C18)
Flow rate : 1.0 ml per minutes
Injection volume : 50 µL
Wavelength : 237 nm
Column temperature: ambient
Method : Isocratic
Suitability
requirements:
Resolution
: NLT 8.5 between amlodipine and amlodipine related compound A
Tailing factor
: NMT 2.0 for both amlodipine and amlodipine related compound A
Relative standard deviation: NMT 1.0% for amlodipine
and NMT 5.0% for amlodipine related compound A
Sample: System suitability solution
(Note—The run time is about three times the
retention of the amlodipine peak)
Procedure: Inject the blank (one time), System
suitability solution (one time), standard solution (six times) and test
solution (two times) in the chromatograph.
Calculation :
The content per tablet is calculated by the equation;
|
mg/
tablet
|
=
|
Mean test area
|
x
|
Wt. of std
(mg)
|
x
|
2
|
x
|
50
|
x
|
50
|
x
|
Std Potency
(as is)
|
x
|
Avg. Wt
(mg)
|
x
|
408.88
|
|
Mean std. area
|
50
|
|
50
|
|
Wt of spl. (mg)
|
|
2
|
|
100
|
|
567.06
|
The
percentage of the content is calculated by the equation;
|
|
|
