Chiral separation of phenylalanine and tryptophan by capillary electrophoresis using a mixture ofβ-CD and chiral ionic liquid ([TBA] [<scp>l</scp>-ASP]) as selectors

In this paper, a simple, effective and green capillary electrophoresis separation and detection method was developed for the quantification of underivatized amino acids (dl-phenylalanine; dl-tryptophan) using -Cyclodextrin and chiral ionic liquid ([TBA] [l-ASP]) as selectors. Separation parameters such as buffer concentrations, pH, -CD and chiral ionic liquid concentrations and separation voltage were investigated for the enantioseparation in order to achieve the maximum possible resolution. A good separation was achieved in a background electrolyte composed of 15mm sodium tetraborate, 5mm-CD and 4mm chiral ionic liquid at pH9.5, and an applied voltage of 10kV. Under optimum conditions, linearity was achieved within concentration ranges from 0.08 to 10 mu g/mL for the analytes with correlation coefficients from 0.9956 to 0.9998, and the analytes were separated in less than 6min with efficiencies up to 970,000 plates/m. The proposed method was successfully applied to the determination of amino acid enantiomers in compound amino acids injections, such as 18AA-I, 18AA-II and 3AA. Copyright (c) 2013 John Wiley & Sons, Ltd.