Stationary Phase Solvation and the Retention Mechanism in Reversed-phase Liquid Chromatography PDF Download
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Author: Lynn Alison Cole
Publisher:
ISBN:
Category :
Languages : en
Pages : 338
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Book Description
Author: Lynn Alison Cole
Publisher:
ISBN:
Category :
Languages : en
Pages : 338
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Book Description
Author: Lay Choo Tan
Publisher:
ISBN:
Category :
Languages : en
Pages : 628
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Author: Jun Dai
Publisher:
ISBN:
Category :
Languages : en
Pages : 626
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Book Description
Author: Nelu Grinberg
Publisher: CRC Press
ISBN: 135165067X
Category : Medical
Languages : en
Pages : 158
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Book Description
For more than five decades, scientists and researchers have relied on the Advances in Chromatography series for the most up-to-date information on a wide range of developments in chromatographic methods and applications. For Volume 54, the series editors have invited established, well-known chemists to offer cutting-edge reviews of chromatographic methods applied in the life sciences that emphasize the underlying principle of separation science. The clear presentation of topics and vivid illustrations for which this series has become known makes the material accessible and engaging to analytical, biochemical, organic, polymer, and pharmaceutical chemists at all levels of technical skill.
Author: Salvatore Fanali
Publisher: Elsevier
ISBN: 0323999999
Category : Science
Languages : en
Pages : 886
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Book Description
Liquid Chromatography: Fundamentals and Instrumentation, Third Edition offers a single source of authoritative information on all aspects of the practice of modern liquid chromatography. The book gives those working in academia and industry the opportunity to learn, refresh, and deepen their understanding of the field by covering basic and advanced theoretical concepts, recognition mechanisms, conventional and advanced instrumentation, method development, data analysis, and more. This third edition addresses new developments in the field with updated chapters from expert researchers. The book is a valuable reference for research scientists, teachers, university students, industry professionals in research and development, and quality control managers. Emphasizes the integration of chromatographic methods and sample preparation Provides important data related to complex matrices, sample preparation, and data handling Gives background information to facilitate the choice of LC sub-technique and experimental conditions, mobile and stationary phases, detectors, data processing, and more Offers comprehensive updates to all chapters Includes new chapters on chiral recognition, co-solvents and mobile phase additives, physicochemical measurements, and identification and quantitation in mass spectrometry
Author: R.M. Smith
Publisher: Elsevier
ISBN: 0080858651
Category : Science
Languages : en
Pages : 479
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Book Description
This book brings together a number of studies which examine the ways in which the retention and selectivity of separations in high-performance liquid chromatography are dependent on the chemical structure of the analytes and the properties of the stationary and mobile phases. Although previous authors have described the optimisation of separations by alteration of the mobile phase, little emphasis has previously been reported of the influence of the structure and properties of the analyte. The initial chapters describe methods based on retention index group increments and log P increments for the prediction of the retention of analytes and the ways in which these factors are influenced by mobile phases and intramolecular interactions. The values of a wide range of group increments in different eluents are tabulated. Different scales of retention indices in liquid chromatography are described for the comparison of separations, the identification of analytes and the comparison of stationary phases. Applications of these methods in the pharmaceutical, toxicology, forensic, metabolism, environmental, food and other fields are reviewed. The effects of different mobile phases on the selectivity of the retention indices are reported. A compilation of sources of reported retention index values are given. Methods for the comparison of stationary phases based on the interactions of different analytes are covered, including lipophilic and polar indices, shape selectivity comparisons, their application to novel stationary phases, and chemometric methods for column comparisons.
Author: Patrice Renée Fields
Publisher:
ISBN:
Category :
Languages : en
Pages : 211
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Book Description
This body of work is a continuation of work previously completed in our group that examines the retention properties of surface confined ionic liquid (SCIL) stationary phases under reversed-phase and supercritical fluid chromatographic conditions. SCIL's have been shown to be useful for separating a variety of both organic and inorganic compounds. However, there has been little work done to elucidate the different retention mechanisms and properties that allow for the wide range of retention modes observed. The first chapter provides a brief history and survey of the properties of ionic liquids. The first chapter also includes an overview of the linear solvation free energy relationship (LSER), which is used to characterize the retention of solute sets containing both neutral and ionizable compounds in under reversed-phase and supercritical conditions. This chapter also provides insight into the evolution and development of molecular solute descriptors. The second chapter discusses several methods that can be employed to modify the LSER model to account for electrostatic interactions between the SCIL stationary ohases and ionizable solutes in reversed-phase chromatography. The P, D and J solute descriptors are evaluated based on their ability to fit the retention of ionizable solutes to the LSER model and to produce coefficient values that are consistent with the underlying molecular interactions and what has been previously reported in reversed-phase studies. The third chapter investigates the use of the LSER model to characterize the retention mechanism of two SCIL stationary phases under supercritical conditions. The LSER coefficients generated via the multiple linear regression of chromatographic retention data are compared and analyzed for statistical difference from one another. The two SCIL phases are further compared to a 2-ethylpyridine (EP) stationary phase, which is more commonly used in chromatography with compressible fluids. This chapter further examines the viability of the P and J solute descriptors to describe the electrostatic interactions between the SCIL stationary phases and ionizable solutes under supercritical conditions. The fourth chapter examines the ion exchange properties of several SCIL stationary phases. A series of small inorganic ions in acetonitrile-water mixtures are used to probe mechanistic differences in the stationary phases due to the substituents attached to the exchange moiety after correcting for loading differences between the phases. Connections have been made between the observed retention properties and the solvation of both the anion analytes and the stationary phase. The fifth chapter summarizes the findings of the previous chapters and offers suggestions for the future directions for this project while the appendix describes a method for estimating the viscosity of binary and ternary supercritical fluids. The estimates are based on a form of Darcy's law and relates the effect of temperature, pressure and flow rate on the estimates.
Author: Won Jo Cheong
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 690
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Book Description
Author: Roman Kaliszan
Publisher: Wiley-Interscience
ISBN:
Category : Science
Languages : en
Pages : 328
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Book Description
The use of computers in numerical characterization of molecular structures has given chemists fundamentally new information on chemical structures, leading to major developments in physical, analytical, and medicinal chemistry. This book, written by a pioneer in the field, extends and updates research on quantitative structure retention relationships (QSRR) by consolidating and critically reviewing the extensive literature on the subject while providing basic theoretical and practical information required in all investigations involving chromatography, analytical chemistry, biochemistry, and pharmaceutical research. Coverage includes detailed discussions of the general theories and mechanisms of chromatographic separations, prediction of retention coefficients, statistical techniques and formal requirements of QSRR studies, specific applications of chromatographic data, and much more. Also provides several carefully selected figures and tables plus extensive bibliographies.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 726
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Book Description
Investigation and control of alkylsilane stationary phase structure in reversed phase liquid chromatography is presented. Raman spectroscopy is used to probe thealkyl chain conformational order and interchain coupling as a function of various chromatographic conditions. A new method is further developed to fabricate alkylsilane stationary phases with controlled surface coverage. The alkyl chain conformational order and interchain coupling of a series of high-density docosylsilane (C22) bonded stationary phases is shown as a function of temperature, surface coverage, polymerization method, common solvents and solutes. The conformational order of C22 stationary phases is compared to that of octadecylsilane (C18) stationary phases to understand the chain length effect on stationary phase structure. The conformational order information as indicated by Raman spectral order indicators for a C22 phase are correlated with the capacity factor and separation efficiency for each solute studied to gain insight into the retention mechanism. These studies help to understand the origin of stationary phase shape selectivity and the separation process in general. Based on these results, the molecular pictures at the stationary phase/solvent interface are proposed. The effect of pressurized solvent environments on two C18 phases is studied to obtain direct evidence for changes in stationary phase structure due to pressure. These changes are compared to effects of solvation relative to air in the same solvents. In addition, Raman spectral order indicators are identified for perdeuterated alkyl-containing system. This study provides a foundation for studying stationary phase structure in complex systems comprised of long alkyl-containing solutes. A further development of a new method is presented as well for synthesizing alkylsilane stationary phases with precisely controlled surface coverage by using a displaceable surface template monolayer of n-alcohol. A mechanism for this process is proposed based on the studies of n-alcohol concentration and chain length effect on the stationary phase surface coverage. The utility of these new stationary phases as chromatographic support is demonstrated. The shape selectivity for these new phases is comparable to or better than similar phases prepared by conventional methods.
