Enantioselective determination of thyroxine enantiomers by ligand-exchange CE with UV absorbance and ICP-MS detection.
A simple CE method has been developed for the separation and determination of thyroxine (T4) enantiomers in pharmaceutical formulations. The method was based on ligand-exchange mechanism using a Cu(II)/L-proline complex as chiral selector. The effects of different parameters affecting separation such as chiral selector concentration, organic additive, buffer pH and temperature were investigated. A baseline separation of the two enantiomers was obtained at a Cu(II)/L-proline ratio of 1:8 in a borate buffer (15 mmol/L, pH 9.6) containing 10% v/v acetonitrile. Under the optimized conditions, precision linearity range and detection limits of the developed enantioselective CE method were evaluated and compared using two different detection systems: conventional UV detection at 226 nm and iodine (127I)specific detection ("chiral speciation") with ICP-MS. Both methodologies show adequate analytical performance characteristics with detection limits around 0.30 microg/mL for each enantiomer of T4. Finally, a levothroid pharmaceutical formulation sample was successfully analyzed using both developed methods CE-UV and CE-ICP-MS.
Department of Physical and Analytical Chemistry, University of Oviedo, Oviedo, Spain.
Jianzhen
J
Kang
Daniel
D
Kutscher
Maria
M
Montes-Bayón
Elisa
E
Blanco-González
Alfredo
A
Sanz-Medel
D019075:Electrophoresis, Capillary / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D013058:Mass Spectrometry / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D013696:Temperature; D013974:Thyroxine / Q000737:chemistry*
D008024:Ligands; D013974:Thyroxine