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Title: Thermodynamic analysis of the heterogeneous binding sites of molecularly imprinted polymers

Abstract

The thermodynamic interactions of two polymers, one Fmoc-L-Trp-imprinted (MIP), the other one an unimprinted reference (NIP), with the two Fmoc-tryptophan enantiomers were studied by frontal analysis, which allows accurate measurements of the adsorption isotherms. These isotherms were acquired at temperatures of 40, 50, 60, and 70 C, for sample concentrations ranging between 0.005 and 40 mM. The mobile phase used was acetonitrile with one percent acetic acid as an organic modifier. Within the measured concentration ranges, the tri-Langmuir isotherm model accounts best for the isotherm data of both enantiomers on the MIP, the bi-Langmuir model for the isotherm data of Fmoc-L-Trp on the NIP. These isotherm models were selected using three independent processes: statistical tests on the results from regression of the isotherm data to different isotherm models; calculation of the affinity energy distribution from the raw isotherm data; comparison of the experimental and the calculated band profiles. The isotherm parameters obtained from these best selected isotherm models showed that the enantiomeric selectivity does not change significantly with temperature, while the affinity of the substrates for both the MIP and the NIP decrease considerably with increasing temperatures. These temperature effects on the binding performance of the MIP were clarified bymore » considering the thermodynamic functions (i.e., the standard molar Gibbs free energy, the standard molar entropy of adsorption, and the standard molar enthalpy of adsorption) for each identified type of adsorption sites, derived from the Van't Hoff equation. This showed that the entropy of transfer of Fmoc-L-Trp from the mobile to the MIP stationary phase is the dominant driving force for the selective adsorption of Fmoc-L-Trp onto the enantioselective binding sites. This entropy does not change significantly with increasing temperatures from 40 to 70 C.« less

Authors:
 [1];  [2];  [3]
  1. University of Tennessee, Knoxville (UTK)
  2. University of Tennessee and Rzeszow University of Technology, Poland
  3. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
989604
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chromatography A; Journal Volume: 1101; Journal Issue: 2006
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; THERMODYNAMICS; POLYMERS; TRYPTOPHAN; ADSORPTION ISOTHERMS; ENERGY SPECTRA; ENTHALPY; ENTROPY; FREE ENTHALPY; PERFORMANCE; ENANTIOMORPHS; Fmoc-L-tryptophan imprinted polymers; frontal analysis; isotherm parameters; affinity distribution; heterogeneous binding sites; temperatures; overloaded band profiles; enantiomer selectivity; Van't Hoff plot; entropy; enthalpy

Citation Formats

Kim, Hyunjung, Kaczmarski, Krzysztof, and Guiochon, Georges A. Thermodynamic analysis of the heterogeneous binding sites of molecularly imprinted polymers. United States: N. p., 2005. Web.
Kim, Hyunjung, Kaczmarski, Krzysztof, & Guiochon, Georges A. Thermodynamic analysis of the heterogeneous binding sites of molecularly imprinted polymers. United States.
Kim, Hyunjung, Kaczmarski, Krzysztof, and Guiochon, Georges A. Tue . "Thermodynamic analysis of the heterogeneous binding sites of molecularly imprinted polymers". United States.
@article{osti_989604,
title = {Thermodynamic analysis of the heterogeneous binding sites of molecularly imprinted polymers},
author = {Kim, Hyunjung and Kaczmarski, Krzysztof and Guiochon, Georges A},
abstractNote = {The thermodynamic interactions of two polymers, one Fmoc-L-Trp-imprinted (MIP), the other one an unimprinted reference (NIP), with the two Fmoc-tryptophan enantiomers were studied by frontal analysis, which allows accurate measurements of the adsorption isotherms. These isotherms were acquired at temperatures of 40, 50, 60, and 70 C, for sample concentrations ranging between 0.005 and 40 mM. The mobile phase used was acetonitrile with one percent acetic acid as an organic modifier. Within the measured concentration ranges, the tri-Langmuir isotherm model accounts best for the isotherm data of both enantiomers on the MIP, the bi-Langmuir model for the isotherm data of Fmoc-L-Trp on the NIP. These isotherm models were selected using three independent processes: statistical tests on the results from regression of the isotherm data to different isotherm models; calculation of the affinity energy distribution from the raw isotherm data; comparison of the experimental and the calculated band profiles. The isotherm parameters obtained from these best selected isotherm models showed that the enantiomeric selectivity does not change significantly with temperature, while the affinity of the substrates for both the MIP and the NIP decrease considerably with increasing temperatures. These temperature effects on the binding performance of the MIP were clarified by considering the thermodynamic functions (i.e., the standard molar Gibbs free energy, the standard molar entropy of adsorption, and the standard molar enthalpy of adsorption) for each identified type of adsorption sites, derived from the Van't Hoff equation. This showed that the entropy of transfer of Fmoc-L-Trp from the mobile to the MIP stationary phase is the dominant driving force for the selective adsorption of Fmoc-L-Trp onto the enantioselective binding sites. This entropy does not change significantly with increasing temperatures from 40 to 70 C.},
doi = {},
journal = {Journal of Chromatography A},
number = 2006,
volume = 1101,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}