Assay: (By HPLC)
Chromatographic
system:
Column : C18 (25cm x 4.6mm), 5 µm
Flow rate : 1.0ml per minute
Detection : 292nm
Injection volume : 20µl
Column temperature : Ambient
Mobile phase:
Methanol: Acetonitrile with 0.5% Triethylamine
(95:5).
Standard Preparation:
Accurately
weight and transfer about 50mg of sildenafil citrate WS & 30 dapoxetine
hydrochloride WS in 50ml dry volumetric flask. Dissolve in mobile phase and
dilute to volume with mobile phase. Dilute 5ml of above solution to 25ml with
mobile phase.
Sample Preparation:
Weigh
& powder 20 tablets. Weigh accurately a quantity of the powder eq. to 50 mg
of sildenafil citrate and 30 mg of Dapoxetine Hydrochloride into a 50 ml
volumetric flask. Sonicate in sufficient quantity in mobile phase and dilute to
50ml volume with mobile phase. Dilute 5.0ml of this solution to 25 ml with
mobile phase.
Procedure:
Filter
through a 0.45-μm pore size nylon membrane and separately injects 20 μL of the
blank standard solution and sample solution into the chromatography system,
record the chromatograph and the measure the response for the major peaks.
System suitability parameter:
The
column efficiency is not less than 2000 theoretical plates, the tailing factor
is not more than 2.0 and the relative standard deviation for six replicate
injections of respective standard solution is not more than 2.0%.
Calculation:
For Sildenafil Citrate:
For Dapoxetine Hydrochloride:
