Chemically Modified Silica Surfaces in Chromatography

Chemically Modified Silica Surfaces in Chromatography
Author: Martin J. J. Hetem
Publisher:
Total Pages: 204
Release: 1993
Genre: Chromatographic analysis
ISBN:

The first part discusses several investigations into the optimization of deactivation and coating both of fused silica capillary columns for GC and of a nonporous silica model substrate. The second part describes surface characterization studies of a number of selected chemically modified silica gels: when modified silica gels are used in RPHPLC practice, unfavorable changes in chromatographic performance occur. The observed changes in surface structure are discussed in detail.

Silane Coupling Agents

Silane Coupling Agents
Author: Edwin P. Plueddemann
Publisher: Springer Science & Business Media
Total Pages: 238
Release: 2013-11-11
Genre: Science
ISBN: 1489903429

* It has been rumored that a bumble bee has such aerodynamic deficiencies that it should be incapable of flight. Fiberglass-reinforced polymer com posites, similarly, have two (apparently) insurmountable obstacles to per formance: 1) Water can hydrolyze any conceivable bond between organic and inorganic phase, and 2) Stresses across the interface during temperature cycling (resulting from a mismatch in thermal expansion coefficients) may exceed the strength of one of the phases. Organofunctional silanes are hybrid organic-inorganic compounds that are used as coupling agents across the organic-inorganic interface to help overcome these two obstacles to composite performance. One of their functions is to use the hydrolytic action of water under equilibrium condi tions to relieve thermally induced stresses across the interface. If equilib rium conditions can be maintained, the two problems act to cancel each other out. Coupling agents are defined primarily as materials that improve the practical adhesive bond of polymer to mineral. This may involve an increase in true adhesion, but it may also involve improved wetting, rheology, and other handling properties. The coupling agent may also modify the inter phase region to strengthen the organic and inorganic boundary layers.

Structure and Retention in Chromatography

Structure and Retention in Chromatography
Author: Kaliszan
Publisher: CRC Press
Total Pages: 230
Release: 1997-05-22
Genre: Science
ISBN: 9789057020285

This book presents an update on the basics, trends and achievements of chemometric methodology required to study the relation between the chemical structure of solutes and their retention in various chromatographic systems. The author critically analyzes hundreds of relevant papers published during the past two decades. In this period, chemometrics has evolved into an established research and practice area of interest to scientists ranging from chromatographers to environmental and medicinal chemists. Although emphasis is placed on the more recent findings, readers will also find the basic theories required to solve specific problems. It should prove advantageous for contemporary chemists and related scientists if they switch from thermodynamics - in practice often inappropriate - to a statistically based (and limited) chemometric approach.

Chromatography Today

Chromatography Today
Author: C.F. Poole
Publisher: Elsevier
Total Pages: 1037
Release: 2012-12-02
Genre: Science
ISBN: 0444596194

Chromatography Today provides a comprehensive coverage of various separation methods: gas, liquid, thin-layer, and supercritical fluid-chromatography, and capillary electrophoresis. Particular attention is paid to the optimization of these techniques in terms of kinetic parameters and retention mechanisms. When these facts are understood, method selection and optimization becomes a more logical process. Sample preparation methods are treated fully as they frequently represent an integral part of the total analytical method. Also described are preparative-scale separations used for isolating significant amounts of product which are generally achieved under conditions that are not identical to those used for analytical separations. The most common hyphenated methods used for sample identification are discussed from the perspective of the information they yield and the requirements of common interfaces. The scope and level of discussion are designed to be appropriate for various user groups. This book should be suitable for use as a graduate-level student textbook in separation science, a text for professional institutes offering short courses in chromatography, and as a self-study guide for chromatographers to refresh their knowledge of the latest developments in the field. The book is extensively illustrated with over 200 figures, 110 tables and 3,300 references, largely to the contemporary literature.