STEREOSELECTIVE HPLC DETERMINATION OF THYROXINE ENANTIOMERS IN PHARMACEUTICALS

Abstract

Direct chiral liquid chromatographic method for the separation and determination of the thyroxine enantiomers in pharmaceutical preparations has been developed. Enantioselective separation was performed on the teicoplanin-based Chirobiotic T (250 mm × 4.6 mm, 5 µm) column in reversed-phase mode. The effects of the mobile phase composition, the pH, the temperature, and the flow rate on the chromatographic separation were investigated. Baseline separation (RS > 3.0) of the thyroxine enantiomers was obtained with methanol and 0.1% triethylammonium acetate, pH 4.0 (70:30, v/v) as isocratic mobile phase at 1.0 mL/min flow rate. UV detection was performed at 215 nm. The calibration curves of both thyroxine enantiomers were linear over the concentration range of 50–300 µg/mL. The limits of detection were 0.15 µg/mL and 0.20 µg/mL for L- and D-thyroxine, respectively. The method was validated in accordance with International Conference on Harmonization (ICH) guidelines. The proposed method was applied for the determination of L-thyroxine in pharmaceutical preparations.