Nuclear magnetic resonance to study the interactions acting in the enantiomeric separation of homocysteine by capillary electrophoresis with a dual system of γ‐cyclodextrin and the chiral ionic liquid EtCholNTf2 |
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Authors: | Maider Greo Antonio Salgado María Castro‐Puyana María Luisa Marina |
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Institution: | Maider Greño,Antonio Salgado,María Castro‐Puyana,María Luisa Marina |
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Abstract: | The enantiomeric separation of 9‐fluorenylmethoxycarbonyl chloride (FMOC)‐homocysteine (Hcy) by CE was investigated using γ‐CD and the chiral ionic liquid (R)‐(1‐hydroxybutan‐2‐yl)(trimethyl)azanium‐bis(trifluoromethanesulfon)imidate (also called (R)‐N,N,N‐trimethyl‐2‐aminobutanol‐bis(trifluoromethane‐sulfon)imidate) (EtCholNTf2) as chiral selectors. Using 2 mM γ‐CD and 5 mM EtCholNTf2 in 50 mM borate buffer (pH 9), FMOC‐Hcy enantiomers were separated with a resolution value of 3.8. A reversal in the enantiomer migration order in comparison with the single use of γ‐CD in the separation buffer was obtained. Then, NMR experiments were carried out to elucidate the interactions taking place in the enantiomeric separation of FMOC‐Hcy. NMR analyses highlighted the formation of an inclusion complex since the hydrophobic group of FMOC‐Hcy was inserted into the γ‐CD cavity. Moreover, interactions between EtCholNTf2 and γ‐CD were also observed, suggesting that the chiral ionic liquid would also enter the cavity of the γ‐CD. |
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Keywords: | Capillary electrophoresis Chiral ionic liquids Homocysteine NMR |
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