A Validated Simultaneous Rp-hplc Method

A new RP-HPLC method was developed for selective and simultaneous determination of of Desogestrel and Ethinyl Estradiol Tablets. The chromatographic separation was achieved on a Zorbax SB C-18, 4.6 x 250mm, and 5μ column. The gradient LC method employs solutions A and B as mobile phase. The solution A milliQ water and acetonitrile in the ratio of 90:10 and degas and solution B contains a mixture of Milli Q water and acetonitrile in the ratio of 5:95 and degas. The flow rate was 1.0 ml/min and the detection wavelength was 225 nm. In the developed HPLC method, the resolution between Desogestrel, Ethinyl Estradiol and its potential impurities, namely Imp-1, Imp-2 and Imp-3 was found to be greater than 3. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in alkaline medium and oxidative stress conditions. Degradation product formed during base hydrolysis was found to be Imp-3. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.5%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.