Enantioseparation of Dansylated Amino Acids by Ligand-exchange Capillary Electrophoresis Using L-phenylalaninamide, L-lysine or L-threonine as Chiral Selector

Abstract

Abstract. In recent years enantioseparation of both active pharmaceutical ingredients and bio molecules such as amino acids became more and more necessary because in most cases the two stereo forms exhibit different pharmacological effects. This article deals with the chiral separation of dansylated amino acids by ligand-exchange capillary electrophoresis using L-phenylalaninamide, L-lysine and L-threonine as chiral selectors. Experiments with different central metal ions such as Cu(II), Co(II), Cd(II), Ni(II) and Zn(II) were carried out. Optimal conditions were found out by studying the effect of the pH and the selector molarity on the chiral resolution. Best separation was obtained for the Cu(II)/L-lysine complex, showing a chiral resolution up to 17 for Dns-DL-Met. (doi: 10.5562/cca1762)

l‐Lysine‐derived ionic liquids as chiral ligands of Zn(II) complexes used in ligand‐exchange CE

“…Because of high dissociation of silanol at pH 8.2, negative charges on the capillary wall induced an EOF of solvent toward the cathode, which showed an opposite direction to the migration of analytes . Thus, the EOF was a special resistance of sample migration in CLE‐CE system with Zn(II) as central ion while the value of μ eo was minus in this experiment . As displayed in Fig.…”

“…Samples were siphoned to capillary for 10 s at 15.0 cm height and separated at –20 kV . The background solution in CE for this study composed of 5.0 mM ammonium acetate, 100.0 mM boric acid, desired concentration of Zn(II), and ligands, adjusted to desired pH value with solid Tris.…”

“…In general, chiral resolution ( R s) in CE is achieved from an enantioselective interaction between the analytes and various types of chiral selectors, such as cyclodextrins, macrocyclic antibiotics, carbohydrates, chiral crown ethers, proteins, and chiral metal complexes . The use of such chiral metal complexes for enantioseparation following ligand‐exchange principle has shown great potential because of its alluring simplicity and notable specificity for chiral separation of biomolecules, including amino acids (AAs), hydroxyl acids, and peptides . Although this complexation‐based separation method is greatly expected and continuously studied, it has faced a pressing challenge that the species of ligands with good performance in chiral ligand‐exchange CE (CLE‐CE) are just limited within several kinds, such as AAs , amino amides , and a few special AAs derivatives .…”

Chiral separation by ligand-exchange

“…Sympathomimetics and ß-blockers were resolved also with the Cu(II) complexes of Ltartaric acid and L-threonine [32]. Recently the influence of different central metal ions such as Cu(II), Co(II), Cd(II), Ni(II) and Zn(II) on enantioseparation of dansylated amino acids using L-phenylalaninamide, L-lysine and L-threonine as chiral selectors was studied [33]. Figure 8 shows the chiral separation of separation of Dns-DL-Asp, Dns-DL-Met, Dns-DL-Asp, Dns-DL-α-ABA and Dns-DL-Leu with L-lysine as chiral selector.…”

Chiral Separation by Ligand Exchange

“…Recently the influence of different central metal ions such as Cu(II), Co(II), Cd(II), Ni(II) and Zn(II) on enantioseparation of dansylated amino acids using L-phenylalaninamide, L-lysine and Lthreonine as chiral selectors was studied [33]. Figure 8 shows the chiral separation of separation of Dns-DL-Asp, Dns-DL-Met, Dns-DL-Asp, Dns-DL-α-ABA and Dns-DL-Leu with L-lysine as chiral selector.…”