Enantioselective resolution of biologically active dipeptide analogs by high-performance liquid chromatography applying Cinchona alkaloid-based ion-exchanger chiral stationary phases

Attila Bajtai, István Ilisz, Dian H.O. Howan, Gábor K. Tóth, Gerhard K.E. Scriba, Wolfgang Lindner, Antal Péter

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Sixteen pairs of enantiomeric dipeptides were separated on four chiral ion-exchanger-type stationary phases based on Cinchona alkaloids. Anion-exchangers (QN-AX, QD-AX) and zwitterionic phases [ZWIX(+)™ and ZWIX(−)™] were studied in a comparative manner. The effects of the nature and concentrations of the mobile phase solvent components and organic salt additives on analyte retention and enantioseparation were systematically studied in order to get a deeper insight into the enantiorecognition mechanism. Moreover, experiments were performed in the temperature range 10–50 °C to calculate thermodynamic parameters like changes in standard enthalpy, Δ(ΔH°), entropy, Δ(ΔS°), and free energy, Δ(ΔG°) on the basis of van't Hoff plots derived from the ln α vs. 1/T curves. Elution sequences of the dipeptides were determined in all cases and, with a few exceptions, they were found to be opposite on the pseudoenantiomeric stationary phases as of QN-AX/QD-AX and of ZWIX(+) and ZWIX(−). The stereoselective retention mechanism is based on electrostatically driven intermolecular interactions supported by additional interaction increments mainly determined by the absolute configuration of the chiral C8 and C9 atoms of the quinine and quinidine moieties.

Original languageEnglish
Article number460574
JournalJournal of Chromatography A
Volume1611
DOIs
Publication statusPublished - Jan 25 2020

Keywords

  • Cinchona alkaloid-based weak anion-exchanger and zwitterionic chiral stationary phases
  • Dipeptides
  • High-performance liquid chromatography

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

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