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| Author | : Raymond P. W. Scott |
| Publisher | : |
| Total Pages | : 288 |
| Release | : 1993-05-24 |
| Genre | : Nature |
| ISBN | : |
Deals with silica gel from the perspective of both the analytical chemist and chromatographer. Provides the reader with a basic understanding of the physical and chemical properties of silica gel and bonded phases as well as how these properties impact on the quality of the separations that are achieved by them.
| Author | : Michael David Bair |
| Publisher | : |
| Total Pages | : |
| Release | : 2011 |
| Genre | : Chemistry |
| ISBN | : |
ABSTRACT: Central to the advancement of reversed-phase high-performance liquid chromatography (RPLC) is to develop new synthetic strategies for manufacturing stationary phase materials. Methods to improve the efficiency, retention properties, and chemical stability of stationary phases are always being investigated. The work presented focuses on two new synthesis schemes aimed at improving monomeric silica-based stationary phases in these respects. The first study involves "pre-capping" Type-B silica. Previous work showed that monomeric stationary phases made by pre-treating the silica surface with small amounts of trimethylsilane (TMS) reagents prior to C18 silanization showed vast improvements in the chromatographic efficiency, phase loading, and retention with a maximum at approx. 5% pre-capping. It was concluded that this pre-capping step improved efficiency by selectively neutralizing the most reactive highly-acidic silanol sites, so-called silanol "hot spots," producing a more energetically-homogenous surface prior to exhaustive C18 derivatization that subsequently yielded a more evenly-distributed alkyl bonding arrangement. These previous studies were performed on Type-A silica, an older variety of silica gel material containing higher levels of metal impurities than the Type-B silica used today. It has since been argued that metallic impurities are the primary cause of silanol hot-spots, and that pre-capping Type-B silica would have little or no effect, however the experimental evidence has yet to be produced, and there exists the potential for heterogeneous silanol reactivity inherent in the amorphous silica gel regardless of purity. The purpose of the work presented here is to determine the effects of TMS pre-capping on Type-B silica as compared to the previous Type-A results, with the goal of establishing pre-capping protocol for Type-B silica and to form a better understanding of its chemistry. The current work performed on three Type-B silica substrates of various physical and chemical properties demonstrated optimal TMS pre-capping at approximately 2.5%. The results at this level show only a slight improvement in efficiency for non-polar compounds ( 25%) was observed for some drug compounds and bases under buffered conditions, with the magnitude of the improved efficiencies correlating with metal impurity content and physical parameters of the silica substrate. Pre-capping also resulted in a slight decrease in retention and hydrolytic stability due to a decrease in bonded phase density. The results lend supporting evidence that metal impurities are the primary source of highly acidic silanols, but they also suggest a means to improve efficiency of basic analytes on certain Type-B silica substrates. It was concluded that TMS pre-capping Type-B silica is best done at low levels (
| Author | : Davy Guillarme |
| Publisher | : Royal Society of Chemistry |
| Total Pages | : 467 |
| Release | : 2012 |
| Genre | : Science |
| ISBN | : 1849733880 |
This book presents a comprehensive overview of UHPLIC and is essential reading to newcomers to field and postgradutes and an essential handbook for experienced users of the technique.
| Author | : Colin Poole |
| Publisher | : Elsevier |
| Total Pages | : 692 |
| Release | : 2023-01-14 |
| Genre | : Science |
| ISBN | : 0323983014 |
Instrumental Thin-Layer Chromatography, Second Edition offers a comprehensive source of authoritative information on all aspects of instrumental thin-layer chromatography. The use of short, topic-focused chapters facilitates identifying information of immediate interest for familiar or emerging uses of thin-layer chromatography. The book gives those working in both academia and industry the opportunity to learn, refresh, or deepen their understanding of fundamental and instrumental aspects of thin-layer chromatography, as well as the tools to interpret and manage chromatographic data. The book serves as a practical consolidated guide to the selection of separation conditions and the use of auxiliary techniques. This fully updated new edition restores the contemporary character of the book for those involved in advancing the technology, analyzing data produced, or applying the technique to new application areas. Some chapters have been consolidated to make room for topics not covered in the first edition, reflecting general changes in the field of thin-layer chromatography, especially in effects-directed detection, convenient interfaces for advanced spectroscopic detection, and greater automation possibilities. This book is a valuable reference for anyone who needs to acquire fundamental and practical information to facilitate progress in research and management functions utilizing information acquired by thin-layer chromatography. Features individual chapters written by recognized authoritative and visionary experts in the field Provides an overview and focused treatment of a single topic Provides tables and diagrams with commonly used data to facilitate practical work, comparison of results, and decision-making Places modern developments in the research literature into a general context not always apparent to inexperienced users of the technique Offers comprehensive updates to all chapters Includes new chapters on instrument platforms, effects-directed detection, data analysis tools, small-scale and microfluidic planar separation systems, and applications to the separation of amino acids and peptides, the analysis of saccharides and lipids, and forensic analysis
| Author | : Varsha Bhagwat |
| Publisher | : |
| Total Pages | : 280 |
| Release | : 1994 |
| Genre | : Chromatographic analysis |
| ISBN | : |
| Author | : Uwe D. Neue |
| Publisher | : Wiley-VCH |
| Total Pages | : 416 |
| Release | : 1997-07-28 |
| Genre | : Science |
| ISBN | : 9780471190370 |
An in-depth guide to HPLC column technology High-performance liquid chromatography and its derivative techniques have become the dominant analytical separation tools in the pharmaceutical, chemical, and food industries; environmental laboratories; and therapeutic drug monitoring. Although the column is the heart of the HPLC instrument and essential to its success, until now, no book has focused on the theory and practice of column technology. HPLC Columns provides thorough, state-of-the-art coverage of HPLC column technology for the practicing technician and academician alike. Along with a comprehensive discussion of the chemical and physical processes of the HPLC column, it includes fundamental principles, separation mechanisms and available technologies, column selection criteria, and special techniques. Special features include: * Comprehensive overview of state-of-the-art HPLC column technology * Explanation of the underlying principles of HPLC columns * Methods for selecting columns * Practical advice on using and applying columns, including examples * Section by M. Zoubair El Fallah on methods development * Special techniques, including preparative chromatography, continuous chromatography, and the simulated moving bed * Troubleshooting section HPLC Columns helps laboratory practitioners make better choices in column selection, methods development, and troubleshooting: it is also an excellent textbook for graduate-level courses and HPLC short courses.
| Author | : Klara Valko |
| Publisher | : Elsevier |
| Total Pages | : 613 |
| Release | : 2000-10-13 |
| Genre | : Science |
| ISBN | : 0080541097 |
Separation Methods in Drug Synthesis and Purification
| Author | : Michal Holcapek |
| Publisher | : Elsevier |
| Total Pages | : 522 |
| Release | : 2017-09-07 |
| Genre | : Technology & Engineering |
| ISBN | : 0128117338 |
Handbook of Advanced Chromatography /Mass Spectrometry Techniques is a compendium of new and advanced analytical techniques that have been developed in recent years for analysis of all types of molecules in a variety of complex matrices, from foods to fuel to pharmaceuticals and more. Focusing on areas that are becoming widely used or growing rapidly, this is a comprehensive volume that describes both theoretical and practical aspects of advanced methods for analysis. Written by authors who have published the foundational works in the field, the chapters have an emphasis on lipids, but reach a broader audience by including advanced analytical techniques applied to a variety of fields. Handbook of Advanced Chromatography / Mass Spectrometry Techniques is the ideal reference for those just entering the analytical fields covered, but also for those experienced analysts who want a combination of an overview of the techniques plus specific and pragmatic details not often covered in journal reports. The authors provide, in one source, a synthesis of knowledge that is scattered across a multitude of literature articles. The combination of pragmatic hints and tips with theoretical concepts and demonstrated applications provides both breadth and depth to produce a valuable and enduring reference manual. It is well suited for advanced analytical instrumentation students as well as for analysts seeking additional knowledge or a deeper understanding of familiar techniques. Includes UHPLC, HILIC, nano-liquid chromatographic separations, two-dimensional LC-MS (LCxLC), multiple parallel MS, 2D-GC (GCxGC) methodologies for lipids analysis, and more Contains both practical and theoretical knowledge, providing core understanding for implementing modern chromatographic and mass spectrometric techniques Presents chapters on the most popular and fastest-growing new techniques being implemented in diverse areas of research
| Author | : H. Rotzsche |
| Publisher | : Elsevier |
| Total Pages | : 425 |
| Release | : 1991-08-21 |
| Genre | : Science |
| ISBN | : 0080858554 |
The primary aim of this volume is to make the chemist familiar with the numerous stationary phases and column types, with their advantages and disadvantages, to help in the selection of the most suitable phase for the type of analytes under study. The book also provides detailed information on the chemical structure, physico-chemical behaviour, experimental applicability, physical data of liquid and solid stationary phases and solid supports. Such data were previously scattered throughout the literature. To understand the processes occurring in the separation column and to offer a manual both to the beginner and to the experienced chromatographer, one chapter is devoted to the basic theoretical aspects. Further, as the effectiveness of the stationary phase can only be considered in relation to the column type, a chapter on different column types and the arrangement of the stationary phase within the column is included. The secondary aim of this book is to stimulate the development of new and improved standardized stationary phases and columns, in order to improve the reproducibility of separations, as well as the range of applications.
| Author | : Lukasz Komsta |
| Publisher | : CRC Press |
| Total Pages | : 1070 |
| Release | : 2013-12-20 |
| Genre | : Medical |
| ISBN | : 1466507152 |
Used routinely in drug control laboratories, forensic laboratories, and as a research tool, thin layer chromatography (TLC) plays an important role in pharmaceutical drug analyses. It requires less complicated or expensive equipment than other techniques, and has the ability to be performed under field conditions. Filling the need for an up-to-date, complete reference, Thin Layer Chromatography in Drug Analysis covers the most important methods in pharmaceutical applications of TLC, namely, analysis of bulk drug material and pharmaceutical formulations, degradation studies, analysis of biological samples, optimization of the separation of drug classes, and lipophilicity estimation. The book is divided into two parts. Part I is devoted to general topics related to TLC in the context of drug analysis, including the chemical basis of TLC, sample pleparation, the optimization of layers and mobile phases, detection and quantification, analysis of ionic compounds, and separation and analysis of chiral substances. The text addresses the newest advances in TLC instrumentation, two-dimensional TLC, quantification by slit scanning densitometry and image analysis, statistical processing of data, and various detection and identification methods. It also describes the use of TLC for solving a key issue in the drug market—the presence of substandard and counterfeit pharmaceutical products. Part II provides an in-depth overview of a wide range of TLC applications for separation and analysis of particular drug groups. Each chapter contains an introduction about the structures and medicinal actions of the described substances and a literature review of their TLC analysis. A useful resource for chromatographers, pharmacists, analytical chemists, students, and R&D, clinical, and forensic laboratories, this book can be utilized as a manual, reference, and teaching source.
