Journal of Pharmaceutical and Biomedical Analysis 22 (2000) 667–671 Stability indicating HPTLC method for the estimation of estradiol  P.N. Kotiyan, P.R. Vavia * Pharmaceutical Diision, Department of Chemical Technology (Autonomous), Uniersity of Mumbai, Nathalal Parikh Marg, Matunga, 400 019 Mumbai, India Received 26 November 1998; received in revised form 6 August 1999; accepted 24 August 1999 Abstract Estradiol (ESD) is widely used in post climacteric replacement therapy. Most of the methods used for quantitation are expensive and time consuming. A rapid, selective and precise stability indicating high performance thin layer chromatography method was developed and validated for the estimation of ESD in bulk and pharmaceutical dosage forms. The method employed TLC aluminium plate precoated with silica gel 60F 254 as the stationary phase. The solvent system employed consisted of chloroform – acetone – isopropyl alcohol – glacial acetic acid (9:1:0.4:0.1, v/v/v/v). Such a complex system was essential to obtain a dense and compact spot of the drug at an Rf value of 0.40 0.02. The drug on intentional degradation gave two products with Rf values of 0.52 0.01 and 0.58 0.01 respectively. Spectrodensitometric scanning-integration was performed on a Camag system using a wavelength of 286 nm. The polynomial regression data for the calibration plots exhibited good linear relationship (r =0.9947) over a concentra- tion range of 1–8 g. Recovery studies were also performed at three experimental levels. The recovery data reveals that the RSD for intra-day and inter-day analysis was found to be 1.27% and 1.75%, respectively. The proposed method was found to be stability indicating. Statistical analysis proves that the method is precise, accurate and reproducible, hence can be employed for the routine analysis of the drug. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Estradiol; HPTLC; Stability indicating www.elsevier.com/locate/jpba 1. Introduction Estradiol (ESD), a potent estrogenic hormone, finds wide utility in post-climacteric replacement therapy [1]. It is administered alone or in combi- nation with other hormones by the oral, transder- mal, subcutaneous and intravaginal routes in a variety of dosage forms. Literature reveals a vari- ety of analytical methods for its estimation in pharmaceutical dosage forms as well as biological fluids. The powerful combination of gas or liquid chromatography and mass spectrometry is used to detect and assay ESD in biological fluids [2]. Also, several liquid chromatographic systems [3 – 5], gas  Presented at the III International Symposium and Short Course on Separation Sciences (SSS-98), Bhopal, India-Nov, 1998. * Corresponding author. 0731-7085/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII:S0731-7085(99)00301-5