The correctness of van ’t Hoff plots in chiral and achiral chromatography

Annamária Sepsey, Éva Horváth, Martina Catani, Attila Felinger

Research output: Contribution to journalArticle

Abstract

van ’t Hoff plots (logarithm of the retention factor, ln k, vs. the reciprocal of absolute temperature, 1/T) are commonly used in chromatographic studies to characterize the retention mechanisms based on the determined enthalpy (ΔH) and entropy (ΔS) change of analyte adsorption. In reversed phase liquid chromatography, the thermodynamic parameters could help to understand the retention mechanism. In chiral chromatography, however, the conclusions drawn based on van ’t Hoff plots can be deceptive because several different types of adsorption sites are present on the surface of stationary phase. The influence of heterogeneity, however, cannot be studied experimentally. In this study, we employed two reversed phase columns with different retention mechanisms to show that by serially coupling the columns, the obtained thermodynamic parameters are not related to the results obtained on the respective individual columns. Furthermore, our results show that the experimental conditions – such as flow-rate or choice of instrument – will strongly influence the calculated enthalpy and entropy values.

Original languageEnglish
Article number460594
JournalJournal of Chromatography A
DOIs
Publication statusAccepted/In press - Jan 1 2019

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Entropy
Chromatography
Thermodynamics
Adsorption
Enthalpy
Liquid chromatography
Reverse-Phase Chromatography
Flow rate
Temperature

Keywords

  • Adsorption sites
  • Chiral separation mechanism
  • Enthalpy change
  • Entropy change
  • Thermodynamics
  • van ’t Hoff plot

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

Cite this

The correctness of van ’t Hoff plots in chiral and achiral chromatography. / Sepsey, Annamária; Horváth, Éva; Catani, Martina; Felinger, Attila.

In: Journal of Chromatography A, 01.01.2019.

Research output: Contribution to journalArticle

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