HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF EQUINE ESTROGENS WITH ULTRAVIOLET ABSORBENCY AND ELECTROCHEMICAL DETECTION

The simultaneous separation of a mixture of equine estrogens containing estrone, equilin, equilenin and their corresponding 17 alpha-diols was accomplished by reversed-phase high-performance liquid chromatography (RP-HPLC) on a Nucleosil C-18 column with a mobile phase composed of methanol-water-2-propanol-dichloromethane (45:42.5:7.5:5, v/v). UV absorbance and electrochemical detection were used for the analysis of a standard mixture of equine estrogens. RP-HPLC with UV absorbance detection was applied to the determination of these compounds in pharmaceutical drug substances and drug products after acid hydrolysis of their sodium sulfate esters.