| Author: |
Eli Grushka & Nelu Grinberg
|
| Published in: | CRC Press |
| Release Year: | 2017 |
| ISBN: | 978-1-4987-2678-8 |
| Pages: | 370 |
| Edition: | Volume 53 |
| File Size: | 15 MB |
| File Type: | |
| Language: | English |
Description of Advances In Chromatography
Since the beginning of chiral chromatography in the 1930s, researchers have taken an interest in mechanisms responsible for the resolution of racemic mixtures on optically active adsorbents. It was understood that behind this phenomenon lies “the asymmetric character of the adsorbing surface, which causes it to react differently towards the enantiomorphous components of the racemic compound” [1]. From this, it immediately followed that the stereochemical configuration of enantiomers was the major factor affecting their interaction with the chiral surface. Hence, a study of the dependence of the adsorption affinity on the spatial configuration of solutes seemed to be a key step in the elucidation of the nature of Enantioseparation.
This fundamental program of research took impulse after the famous publication by Dalgliesh, who attempted to explain the separation of enantiomers of amino acids on cellulose-based on spatial considerations. At that time, there were no tools to investigate interactions between a solute and an adsorbent on the molecular level, so researchers used indirect integral characteristics, such as retention factor (k′) and enantioselectivity (α), to elucidate mechanisms resulting in different migration velocities of optical antipodes in a chiral media. This approach is called macroscopic because it disregards the molecular structure of the system under investigation and operates with quantities averaged (in a thermodynamic sense) over large ensembles of molecules and over a certain period of time. Tremendous improvements in molecular techniques made in the past three decades, in particular, in molecular modeling as well as in spectrometric methods (NMR, FT-IR, VCD, etc.) and x-ray crystallography allowed researchers to study solute– selector binding at the microscopic level.
Both these approaches are important in chromatographic research. The application of the molecular techniques makes it possible to understand how a chiral selector discriminates between optical antipodes. These methods cannot, however, explain in full the phenomenon of retention on the chiral stationary phase (CSP). This is because the CSP is not a uniform array of identical chiral sites, each interacting in the same manner with a solute. A real CSP is a heterogeneous solid, including both enantioselective (chiral) sites and nonselective sites; each group of the sites may be, in its turn, heterogeneous as each individual site may slightly differ from other ones of the same type due to differences in the surrounding, minor conformational changes, location in the porous structure of a stationary phase, and so on. A mechanistic understanding of the interaction of a solute with a real stationary phase is a task of an utmost complexity, not yet resolved.
This fundamental program of research took impulse after the famous publication by Dalgliesh, who attempted to explain the separation of enantiomers of amino acids on cellulose-based on spatial considerations. At that time, there were no tools to investigate interactions between a solute and an adsorbent on the molecular level, so researchers used indirect integral characteristics, such as retention factor (k′) and enantioselectivity (α), to elucidate mechanisms resulting in different migration velocities of optical antipodes in a chiral media. This approach is called macroscopic because it disregards the molecular structure of the system under investigation and operates with quantities averaged (in a thermodynamic sense) over large ensembles of molecules and over a certain period of time. Tremendous improvements in molecular techniques made in the past three decades, in particular, in molecular modeling as well as in spectrometric methods (NMR, FT-IR, VCD, etc.) and x-ray crystallography allowed researchers to study solute– selector binding at the microscopic level.
Both these approaches are important in chromatographic research. The application of the molecular techniques makes it possible to understand how a chiral selector discriminates between optical antipodes. These methods cannot, however, explain in full the phenomenon of retention on the chiral stationary phase (CSP). This is because the CSP is not a uniform array of identical chiral sites, each interacting in the same manner with a solute. A real CSP is a heterogeneous solid, including both enantioselective (chiral) sites and nonselective sites; each group of the sites may be, in its turn, heterogeneous as each individual site may slightly differ from other ones of the same type due to differences in the surrounding, minor conformational changes, location in the porous structure of a stationary phase, and so on. A mechanistic understanding of the interaction of a solute with a real stationary phase is a task of an utmost complexity, not yet resolved.
Content of Advances In Chromatography
Chapter 1 Solute–Stationary Phase Interaction in Chiral Chromatography ........1
Leonid D. Asnin, Alberto Cavazzini, and Nicola Marchetti
Chapter 2 The Role of Chromatography in Alzheimer’s Disease Drug
Discovery ............................................................................................ 75
Jessica Fiori, Angela De Simone, Marina Naldi,
and Vincenza Andrisano
Chapter 3 Characterization of the Kinetic Performance of Silica
Monolithic Columns for Reversed-Phase Chromatography
Separations ....................................................................................... 109
Gert Desmet, Sander Deridder, and Deirdre Cabooter
Chapter 4 Recent Advances in the Characterization and Analysis of
Therapeutic Oligonucleotides by Analytical Separation
Methods Coupling with Mass Spectrometry .................................... 143
Su Pan and Yueer Shi
Chapter 5 Uncertainty Evaluation in Chromatography .................................... 179
Veronika R. Meyer
Chapter 6 Comprehensive Two-Dimensional Hydrophilic Interaction
Chromatography × Reversed-Phase Liquid Chromatography
(HILIC × RP–LC): Theory, Practice, and Applications .................. 217
André de Villiers and Kathithileni Martha Kalili
Chapter 7 Sample Preparation for Thin Layer Chromatography ...................... 301
Mieczysław Sajewicz, Teresa Kowalska, and Joseph Sherma
Chapter 8 Modeling of HPLC Methods Using QbD Principles in HPLC ........ 331
Imre Molnár, Hans-Jürgen Rieger, and Robert Kormány
Index ...................................................................................................................... 351
Leonid D. Asnin, Alberto Cavazzini, and Nicola Marchetti
Chapter 2 The Role of Chromatography in Alzheimer’s Disease Drug
Discovery ............................................................................................ 75
Jessica Fiori, Angela De Simone, Marina Naldi,
and Vincenza Andrisano
Chapter 3 Characterization of the Kinetic Performance of Silica
Monolithic Columns for Reversed-Phase Chromatography
Separations ....................................................................................... 109
Gert Desmet, Sander Deridder, and Deirdre Cabooter
Chapter 4 Recent Advances in the Characterization and Analysis of
Therapeutic Oligonucleotides by Analytical Separation
Methods Coupling with Mass Spectrometry .................................... 143
Su Pan and Yueer Shi
Chapter 5 Uncertainty Evaluation in Chromatography .................................... 179
Veronika R. Meyer
Chapter 6 Comprehensive Two-Dimensional Hydrophilic Interaction
Chromatography × Reversed-Phase Liquid Chromatography
(HILIC × RP–LC): Theory, Practice, and Applications .................. 217
André de Villiers and Kathithileni Martha Kalili
Chapter 7 Sample Preparation for Thin Layer Chromatography ...................... 301
Mieczysław Sajewicz, Teresa Kowalska, and Joseph Sherma
Chapter 8 Modeling of HPLC Methods Using QbD Principles in HPLC ........ 331
Imre Molnár, Hans-Jürgen Rieger, and Robert Kormány
Index ...................................................................................................................... 351
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