Separation of Steroids and the Determination of Estradiol Content in Transdermic Patches by Microemulsion Electrokinetic Chromatography

Abstract

A novel microemulsion electrokinetic capillary chromatography (MEEKC) method has been developed which separates a range of nine steroids. A microemulsion containing ethyl acetate, butan-1-ol, sodium dodecyl sulfate, 15% (v/v) acetonitrile and 12 mmol L−1 sodium tetraborate aqueous buffer at pH 9.2 was used with direct UV detection at 200 nm. The method was validated for the determination of 17β-estradiol content, a hormone steroid, in transdermal patches. Adequate sensitivity (DL = 0.88 μg mL−1; QL = 2.65 μg mL−1) without interference from sample excipients was obtained. 17β-Estradiol migrates in approximately 5.4 min. Estrone was used as internal standard and acceptable precision (<1.2% RSD), linearity (r = 0.9996; range from 40.0 to 60.0 μg mL−1), and recovery (100.4 ± 0.9% at three concentration levels) were obtained. The principal advantage of the method is that it is rapid and avoids the need of time consuming and expensive sample pre-treatment steps.