Quantitative determination of sildenafil citrate in herbal medicinal formulations by high-performance thin-layer chromatography

A densitometric high-performance thin-layer chromatographic (HPTLC) method has been established for quantitative determination of sildenafil citrate in herbal medicinal formulations. Chromatography was performed on silica gel 60 F254 HPTLC plates, pre-washed with methanol, with toluene-acetone-methanol, 6 + 2 + 2 (v/v) as mobile phase. The plates were developed vertically, to a distance of 8 cm, in a saturated chamber, and densitometric quantitation was performed at λ = 312 mn by reflectance scanning. Recovery from the herbal medicinal powders and tablets was 83.17% and 99.41%, respectively. The standard sildenafil citrate calibration plot was linear (r = 0.9993) over the concentration range 100-600 ng per spot and the quantitative results showed the sildenafil content of the herbal formulations analyzed was in the range 76.4-85.0 mg (RSD < 3%). This HPTLC technique is complementary to other chromatographic methods and has potential use for routine quality-control analysis.