Chiral ligand exchange countercurrent chromatography: Enantioseparation of amino acids

Abstract

This work deals with the enantioseparation of α-amino acids by chiral ligand exchange high-speed countercurrent chromatography using N-n-dodecyl-l-hydroxyproline as a chiral ligand and copper(II) as a transition metal ion. A biphasic solvent system composed of n-hexane/n-butanol/aqueous phase with different volume ratios was selected for each α-amino acid. The enantioseparation conditions were optimized by enantioselective liquid-liquid extractions, in which the main influence factors, including type of chiral ligand, concentration of chiral ligand and transition metal ion, separation temperature, and pH of the aqueous phase, were investigated for racemic phenylalanine. Altogether, we tried to enantioseparate 15 racemic α-amino acids by the analytical countercurrent chromatography, of which only five of them could be successfully enantioseparated. Different elution sequence for phenylalanine enantiomer was observed compared with traditional liquid chromatography and the proposed interactions between chiral ligand, transition metal ion (Cu ), and enantiomer are discussed.

Strategies for chiral separation: from racemate to enantiomer

“…116 Hydroxypropyl-b-cyclodextrin (HP-b-CD) was further applied to separate ketoconazole, ibuprofen and naringenin within 12.5 h, 7.3 h and 6.5 h, respectively. [117][118][119] Also, N-n-dodecyl-L-hydroxyproline successfully resolved enantiomers such as phenylalanine, valine and isoleucine racemates on an HSCCC device within 2 h. 120 Additionally, other variants such as high-performance centrifugal partition chromatography (HPCPC) and spiral tube CCC have attracted signicant attention. [121][122][123][124] Consequently, it is necessary to develop highly selective CSs, novel solvent systems and high-efficiency variants for the industrialization of CCC.…”

Two-Dimensional Transport Dispersive Model for Separating Glycolic Acid and NaCl with Ligand Exchange Chromatography

“…Ligand exchange chromatography, a kind of separation method with low energy consumption and high efficiency, can purify organic acids and also be used in the separation of GA. This method is based on the difference in interaction force between separation medium and components, shows a good selectivity and separation effect, and is widely used in the separation of sugar, amino acids, and natural substances. , For example, 3-phenyllactic and mandelic acids and phenylalanine could be efficiently separated with ligand exchange chromatography. For that separation method, the preparation of a separation medium, , the effect of process parameter, the process modeling, and process amplification are the main concerns.…”

Counter‐current chromatography melamine‐modified column and its separation mechanism

“…As we all know, relying on its advantage in its unique separation mechanism and high sample loading, CCC has unique merits in the preparative separation of chiral compounds when the suitable chiral ligand was screened as the solvent additive . If a suitable chiral ligand was screened as functional modifier, this work may provide another potential approach to prepare a chiral CCC column and use it for separating chiral compounds with high throughput, which could avoid the extra step to remove the chiral ligand from the chiral monomeric compounds.…”