Solution preparation :
Mobile Phase: Mix 470 ml of methanol and
530 ml of water.
Mobile Phase: Mix 470 ml of methanol and
530 ml of water.
0.002% w/v of hydrocortisone
: Dissolve 20 mg of hydrocortisone in 100 ml
Methanol (50%), Dilute 25 ml of this solution to 250 ml with Methanol (50%).
Standard Solution : Accurately weigh and transfer
25 mg of betamethasone WS
and 20 mg of hydrocortisone (internal standard) in 100 ml volumetric flask, add
70 ml of Methanol (50%) and sonicate for 10 min. and make up the volume with
Methanol (50%).
Dilute 2 ml of this solution to 20 ml with
Methanol (50%).
Test
Solution : Weigh and transfer the powder, equivalent 0.5 mg of
Betamethasone to 20 ml of a 0.002% w/v solution of hydrocortisone
in methanol (50%), shake for 10 minutes and filter through a glass-fibre filter
paper (Whatman GF/C is suitable).
Chromatographic system:
Column : C18 (25-cm
× 5 mm), 10-µm, (Spherisorb ODS 1 is suitable).
Flow rate : 1.4 ml
per minutes
Injection volume : 20 µL
Wavelength : 238 nm
Column temperature: ambient
Method : Isocratic
Procedure: Inject the
blank (one time), standard solution (six times) and test solution (Two times)
in the chromatograph.
Calculation : The content per tablet is calculated by the equation;
