Enantioseparation by chromatographic and electromigration techniques using ligand-exchange as chiral separation principle

Abstract

This article gives a short overview of the application of the principle of chiral ligand-exchange in HPLC, CE, and CEC. Since its introduction by Davankov, more than thousand articles have appeared in this field. Citing all these papers would extend the scope of this review-it would fill several books. Therefore only some milestones are mentioned in this article and it will focus on our own activities in this field. Some new developments are mentioned, and selected biochemical and biomedical application are presented.

Hybrid monolithic columns coated with cellulose tris(3,5-dimethylphenyl-carbamate) for enantioseparations in capillary electrochromatography and capillary liquid chromatography

“…Most of racemates were successfully resolved, and their resolution (Rs) varied from 0.49 to 3.48. Neutral benzoin and trans-stilbene oxide were successfully resolved using mobile phase of ACN/H 2 O (40/60, v/v), while basic tetrahydropalmtine and pindolol were completely resolved with a mobile phase of ACN/H 2 O (containing 5 mM NH 4 Ac, pH 9.7) (30/70, v/v). Typical chromatograms are illustrated in Fig.…”

“…Capillary-based microscale separation technique including capillary electrochromatography (CEC) and capillary liquid chromatography (CLC) is preferred in analytical scale of chiral separation due to low cost, speed, effectiveness and reproducibility [1][2][3][4][5][6]. The state-of-the-art in microseparation techniques has been reviewed, and it has been concluded that monolithic capillary columns are particularly suitable for both CEC and CLC because monolithic columns eliminate the need for frits retaining the stationary phase, and possess good permeability and good peak capacity [7][8][9][10][11][12].…”

Investigation of Enantiomeric Separation of Chiral Drugs by CE Using Cu(II)–Clindamycin Complex as a Novel Chiral Selector

“…Accordingly, Cu(II) was selected as the central metal ion and found to provide a good resolution for the tested drugs. The molar ratio of metal ions to ligands has a strong impact on resolution [26]. In order to make clear the effect of the molar ratio of metal ion to ligand on the enantiomeric separation, the relative amounts of the two components were varied as 2:1, 1:1, 1:2, 1:3 (Cu 2?…”

“…Resolution is due to the difference in complex stability constants of the two mixed complexes with the analyte enantiomers [24]. For enantiomeric resolutions by LE-CE, various ligands, such as L-histidine, aspartame, N,N-didecyl-L-alanine, hydroxyproline, L-proline, D-penicillamine [1,26], have been successfully used as chiral resolving agents for enantiomeric separation of amino acids, organic acids, diamines, and small peptides. Different enantioselectivities were obtained by using these Cu(II) complexes as chiral selectors in CE.…”

A Silica Monolithic Column with Chemically Bonded l-Pipecolic Acid as Chiral Stationary Phase for Enantiomeric Separation of Dansyl Amino Acids by CEC–MS

“…However, no research papers on CEC-MS-based chiral ligand exchange have been published. The major problem is that, in LE-CEC, metal ions are usually required to be added in the mobile phase to form chiral complexes as chiral selectors [26]. The presence of metal ions eliminates the coupling of CEC with MS detection due to the noise resulting from the metal ions.…”