New chiral ligand exchange capillary electrophoresis system with chiral amino amide ionic liquids as ligands

Using chiral amino amide ionic liquids as the ligands, a new chiral ligand exchange capillary electrophoresis method with Cu(II) as the central ion was constructed for enantioseparation of labeled D,L-amino acids. The effects of key parameters, including pH value of the running buffer, the ratio of Cu(II) to chiral amino amide ionic liquids, the concentration of complexes based on Cu(II)-chiral amino amide ionic liquids were investigated. It has been observed that eight pairs of labeled D,L-amino acids could be baseline-separated with a running buffer of 15.0 mM ammonium acetate, 10.0 mM Cu(II) and 20.0 mM L-phenylalaninamide based ionic liquid at pH 5.0. The quantitation of D,L-amino acids was conducted and good linearity (r(2) >= 0.964) was obtained. Furthermore, an assay for determining the enantiomeric purity of D,L-amino acids was developed and the possible enantiorecognition mechanism was discussed briefly. The results indicated that the chiral amino amide ionic liquids could play the role of ligands in chiral ligand exchange capillary electrophoresis system and exhibit great potential in chiral analysis.