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.
ACKNOWLEDGMENTS
The authors (TG and JP) are thankful to the Hermes LabSystems for technical support of this work.
Notes
a n = 6.
b n = 3.