Liquid chromatographic analysis of conjugated and esterified estrogens in tablets

A high-performance liquid chromatographic (HPLC) method was developed for the analysis of conjugated and esterified estrogens in tablets. The 3-sulfate estrogen derivatives were hydrolyzed with acid, mixed with ethinyl estradiol (the internal standard), and extracted into benzene. The liberated 3-phenolic estrogens were converted to dansyl derivatives, separated on an adsorption column, and detected fluorometrically. Estrogens with a 17-keto functional group required a prior reduction to the corresponding 17 beta-hydroxyl derivatives with sodium borohydride in order to be chromatographically resolved. The validity of the proposed method was demonstrated by analyzing samples of commercial tablets of conjugated and esterified estrogens of various strengths.