Determined by liquid chromatography.
Test solution (a): Weigh and powder 20 tablets. Weigh a quantity of the powder containing 50mg amlodipine, dissolve in the mobile phase, dilute to 50.0ml with the mobile phase and centrifuge.
Test solution (b): Dilute 5ml of the test solution (a) to 100ml with mobile phase.
Reference solution (a): A solution of amlodipine besilate reference standard containing 0.005 per cent w/v of amlodipine in the mobile phase.
Chromatographic system:
- A stainless steel column 15cmX3.9mm packed with octadecylsilane bonded to porous silica (5µm),
- Mobile phase: a mixture of 15 volumes of acetonitrile, 35 volumes of methanol and 50 volumes of a solution prepared by dissolving 7.0ml of triethylamine in 1000ml water, adjusted to pH 3.0 with O.P.A.
- Flow rate: 1ml per minute,
- Spectrophotometer set at 237nm,
- Injection volume: 10µl
Inject reference solution (a) and test solution (b).
Calculate the content of Amlodipine in tablets.
Formula:
Area of Test STD Wt.(mg) 5 50 100 Potency
—————–X————–X——-X—————–X——–X—————-X Average wt.
Area of STD 100 50 Test Wt.(mg) 5 100
Alternative Method: By UV Spectrophotometer
Test Solution: Weigh and powder 20 tablets. Weight sample equivalent to 5mg of Amlodipine 100ml volumetric flask add 20ml 0.1M HCl into it and sonicate to dissolve the test sample. Make up to mark with 0.1 M HCl. Filter and check absorbance.
Reference Solution: Weigh 30mg of reference standard of Amlodipine besilate in 50ml of volumetric flask. Add 20ml 0.1 M HCl into it and sonicate to dissolve. Make up to mark with 0.1 M HCl. Dilute 5ml of this solution to 50ml with same solvent.
Check Absorbance of test as well as reference standard at about 362nm in UV Spectrophotometer.
Calculate the content of Amlodipine in the tablets.
Formula:
Area of Test STD Wt.(mg) 5 100 Potency
—————–X————–X——-X——————–X———–X Average wt.
Area of STD 50 50 Test Wt.(mg) 100
