Amino-β-cyclodextrin derivatives with different chain lengths as chiral selectors for separation of dansyl amino acid enantiomers by capillary electrophoresis

To date, cyclodextrins (CDs) and their derivatives are recognized as highly effective chiral selectors in electrophoresis for enantiomer separation due to their numerous advantages. In this study, three amino-β-CD derivatives, including NH₂-β-CD-5 (Mono-(6-(tetraethylenepentamine)-6-deoxy)-beta-Cyclodextrin), NH₂-β-CD-3 (mono-(6-(diethylenetriamine)-6-deoxy)-β-Cyclodextrin), and NH₂-β-CD-1 (6-Monodeoxy-6-monoamino-beta-cyclodextrine) with varying amino substituent chain lengths were employed as chiral selectors in capillary electrophoresis (CE) to examine their chiral selectivity in the separation of five dansylated amino acid enantiomers, namely Dns-DL-Val, Dns-DL-Leu, Dns-DL-Thr, Dns-DL-Phe, and Dns-DL-Ser, as the chain length of the substituent group significantly impacts separation performance. Among the three amino-β-CD derivatives, NH₂-β-CD-5 exhibited superior performance by separating four dansylated amino acid enantiomers, whereas NH₂-β-CD-3 and NH₂-β-CD-1 separated only two and one enantiomers, respectively. Additionally, the effects of pH values, buffer concentrations, and concentrations of the chiral selectors on the separation of dansylated amino acid enantiomers were also investigated. Furthermore, the stability and reproducibility of the three amino-β-CD derivatives were evaluated, with the relative standard deviations (RSDs) of resolution all below 8.2 %.