Download or read book Development and Characterization of New Stationary Phases for Hydrophilic Interaction Liquid Chromatography written by Mohammed Elsayed Abdelatif Ibrahim and published by . This book was released on 2014 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrophilic interaction liquid chromatography (HILIC) has gained high popularity among separation scientists in the last two decades due to its ability to retain polar analytes. Many new HILIC stationary phases with different selectivities have appeared in the recent literature. Such developments require tools which can classify and compare the selectivity of these HILIC columns. In this thesis, straightforward and simple selectivity plots were constructed and used to classify HILIC stationary phases into bare silica, zwitterionic, neutral and amine-based phases. Silica monoliths show weak retention under HILIC conditions. In this thesis, the HILIC retention characteristics of silica monoliths were enhanced through surface modification with hydrophilic cationic latex nanoparticles. High efficiency (H ~ 25-110 μm) separations of carboxylic acids, amino acids and nucleotides were achieved. Due to their positive charge, the latex nanoparticles introduce anion exchange as another source of interaction. Consequently, these latex coated silica monoliths should exhibit mixed mode (HILIC/anion exchange) retention. Herein, the mixed mode retention of three different latex coated silica monoliths was studied. The AS9-SC latex coated silica monolith possessing the highest ion exchange capacity (44.1 μeq/column) separated six chaotropic and kosmotropic anions in less than 2.5 min. Silica is chemically unstable under extreme pH conditions. On the other hand, porous graphitic carbon (PGC) has high pH stability. Being a hydrophobic material, typically usage of PGC is restricted to reversed phase chromatography. In the presented thesis, a carbon-based HILIC stationary phase was developed as a new class of HILIC stationary phases via diazonium chemistry. The potential of this phase (carboxylate-PGC) as a HILIC phase was demonstrated by separation of carboxylic acids, phenols, amino acids and nucleotides. Carboxylate-PGC phase showed different selectivity than 35 columns. The efficiency of carbon-based phases is lower than silica due to slow mass transfer kinetics. Herein, we developed a hybrid phase comprising of 5 μm core-shell silica particles coated with 50 nm anionic carbon nanoparticles. This hybrid phase exhibited the unique selectivity of carbon and the high efficiency of core-shell silica particles. Fast and high efficiency HILIC separations of carboxylates and pharmaceuticals were achieved with efficiencies up to 85,000 plates/m.
Download or read book Liquid Chromatography written by A. Cavazzini and published by Elsevier Inc. Chapters. This book was released on 2013-01-08 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrophilic interaction liquid chromatography (HILIC) has become in the last years a leading technique for the separation of small and large polar molecules. This chapter begins with a discussion about the most relevant characteristics of HILIC mode that makes it a complementary and, in some cases, alternative technique to the more traditional reversed- and normal-phase modes. Subsequently, the fundamentals of retention mechanisms in HILIC are revised in light of the most recent findings in the field. The chapter ends with an overview of the materials used as stationary and mobile phases in HILIC and of the applications of this analytical technique in different branches of science.
Download or read book Development and Characterization of Stationary Phase Gradients for High Performance Liquid Chromatography written by Anna Forzano and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Choosing a stationary phase is the first step in developing a liquid chromatography (LC) separation method, where the selectivity is governed by the differential interactions of the analytes with the stationary and mobile phases. Introducing a gradient in stationary phase functionality allows for tuning of analyte retention, translating to a possible improvement in selectivity and an increase in resolution versus that offered by uniform stationary phases. In this work, C1-silica, phenylbutyl-silica, and phenylbutyl-ammonium opposed continuous stationary phase gradients were fabricated using controlled rate infusion (CRI) on particle packed LC columns. Characterization of the stationary phase was carried out using spectroscopy and LC analysis to relate the ligand density gradient profile to the observed chromatographic parameters. C18-silica gradients were created with a time-dependent acid hydrolysis infusion and demonstrated an increase in resolution when combined with a mobile phase gradient. Phenylbutyl-silica and phenylbutyl-ammonium gradients were produced using an in-situ silanization CRI method. Phenylbutyl-silica gradients were confirmed to be stable and reproducible; however, produced tailing peak shapes. Phenylbutyl-ammonium gradients were utilized to incorporate an ion exchange model into a simulator built by Jeong et al. The phenylbutyl-ammonium gradient was not reproducible but did exhibit an increase in resolution when combined with a mobile phase gradient. Also, the ion exchange model was successfully added within the simulator, with percent differences for retention prediction all under 5 %. This dissertation serves as a proof-of-concept for gradient stationary phases on particle packed LC columns.
Download or read book Hydrophilic Interaction Liquid Chromatography HILIC and Advanced Applications written by Perry G. Wang and published by CRC Press. This book was released on 2011-02-17 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book that comprehensively and systematically describes the new technology of hydrophilic interaction liquid chromatography (HILIC). Hydrophilic interaction chromatography is a separation technique suitable for polar and hydrophilic compounds and orthogonal to reversed phase liquid chromatography. From small organic molecules to proteins, the text explores the many applications of HILIC in the analytical field. Winner of the President's Award for Excellence, the author explains how HILIC can significantly improve analytical throughput by shortening sample preparation procedure, which is one of the bottlenecks for drug discovery and development in the pharmaceutical industry.
Download or read book Preparation and Characterization of Multifunctional Stationary Phases for Multimode Separations written by Asanka Wijekoon and published by . This book was released on 2010 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: High performance liquid chromatography is a powerful analytical technique employed to separate analyte mixtures. Since biomedical sample mixtures contain a very diverse range of compounds; one chromatographic mode is usually unable to separate all components of the mixture. Therefore, there is an increasing need for faster and efficient separations with a broad range of selectivity. To attain better selectivity and efficient separation, and to improve the versatility of the chromatographic column, a new way of preparation of multifunctional stationary phases, suitable for use in multiple chromatographic separation modes, is described. The preparation of multifunctional stationary phases takes advantage of Schiff base chemistry in two different synthetic routes. The first route involves reductive coupling of amino bonded silica with aldehyde containing ligands. The coupling of aldehyde bonded silica with amine containing ligands is the other reaction route. Aldehyde terminated silica is a versatile reactive platform that enables the synthesis of a wide range of stationary phases by attaching amine containing ligands that have diverse functionality. Here the preparation of aldehyde terminated silica was achieved by bonding aldehyde silane to the silica surface. Preparation of aldehyde silane is a novel approach and a successful synthetic scheme of making acetalated aromatic aldehyde silane (AAS- Aldehyde group in the silane has been protected by acetalation) and aromatic aldehyde silane (AS) is invented. The studies confirmed that the synthesized multifunctional chromatographic stationary phases were capable of operating in ion exchange mode, reversed phase mode and hydrophilic interaction liquid chromatographic mode. The studies further concluded that those surfaces have good selectivity for the separation of small polar and charge molecules. The application of the well established Schiff base reaction allowed the incorporation 2H to the bonded phases and is utilized to study the motional dynamics of the bonded ligands in the surface at different temperatures in the presence of a broad range of solvent systems by using 2H wide line NMR spectroscopy. The investigation provides information about the motional dynamic heterogeneity of the bonded ligands, which reflects the existence of surface heterogeneity of the surface.
Download or read book Preparation and characterization of written by Emad Yousif and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: New stationary phase for high performance liquid chromatography had been prepared by the reaction of congo red solution with amberlite anion exchange. The F.T.I.R elemental analyses have configured the attachment of congo red on the resin as has indicated by the physical appearance of the new resin. The resin capacities of newly prepared resin has calculated the resin capacity for the amberlite-congo red resin was found to average 4.8 meq/ gm and for the amberlite resin 3.0 meq./gm. The new stationary phase has been packed into stainless steel column. This has been done by the special teqnique. The chromatographic performance of the packed column was characterized the number of plate numbers, height equivalent of a theoretical plates, capacity factors, selectivity factor and peak asymmetry were measured by analyzing different analysis on the new column using different mobile phases composition and flow rates. The parameters were measured from analasisi of some amino acids such as histidine, phenyl alanine, tyrosine and prolenene. The analysis of amino acids using amberlite-congo red column has performed with an aqueous mobile phase adjusted at pH 2.5.
Download or read book Liquid Chromatography written by Salvatore Fanali and published by Elsevier. This book was released on 2023-04-21 with total page 1084 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid Chromatography: Applications, Third Edition delivers a single source of authoritative information on all aspects of the practice of modern liquid chromatography. The text 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.
Download or read book Development of New Stationary Phases and Their Applications in High Performance Liquid Chromatography written by Haixiao Qiu and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High performance liquid chromatography (HPLC) has proven to be the most widely applicable and versatile technique in separation science. Hydrophilic interaction liquid chromatography (HILIC) has attracted considerable interest and has become a viable option for the separation of polar compounds. Chirality is another major concern in the modern pharmaceutical industry for two reasons: 1). the majority of bio-organic molecules are chiral; 2). enantiomers of a racemic drug may often exhibit different biological activities, pharmacokinetics, and toxicities. The field of enantiomeric separations has reached a clear level of maturity after approximately 30 years of development. However, with the continued emphasis on stereochemistry in drug design and development, chiral separations are in ever increasing demand. The development of new, more effective methods is still challenging and demanding experimentally. This dissertation discusses new research in three areas: 1). Development and application of new HILIC stationary phases for the separation of polar organic compounds. Two types of new HILIC stationary phases have been successfully synthesized and evaluted. One is based on native cyclofructan 6 and another one is a zwitterionic stationary phase based on 3-P,P-diphenylphosphonium-propylsulfonate. Their performance and retention mechanisms in the HILIC mode will be discussed in this dissertation.2). Development and evaluation of new chiral stationary phases. R-naphthylethyl-carbamate cyclofructan 6 (RN-CF6) and dimethylphenyl-carbamate cyclofructan 7 (DMP-CF7) were successfully synthesized and provide enantioselectivity toward a broad range of chiral compounds. They were found to be the best aromatic-functionalized cyclofructan chiral stationary phases and provide enantiomeric separations complementary to the isopropyl-carbamate cyclofructan 6 based chiral stationary phase. This dissertation also describes method development of enantiomeric impurities quantification in chiral reagents. Three macrocyclic chiral stationary phases, including cyclodextrins, macrocyclic glycopeptides and cyclofructans, have been used to determine enantiomeric impurities in new chiral catalysts, auxiliaries and synthons used in asymmetric syntheses. It was found that many of the newer chiral reagents are highly enantiopure, probably due to continual improvements in asymmetric syntheses and purification in the manufacturing process. 3). Development and application of new stationary phases based on a resin substrate instead of silica gel. This dissertation describes methods for binding cyclofructan 6 to resin via "click" chemistry. It was found that these resin based stationary phases appear to have potential in HILIC separations (native cyclofructan 6 bonded to resin as stationary phases) and enantiomeric separations (isopropyl-carbamated cyclofructan 6 bonded to resin).
Download or read book Fundamental Studies on Ultrafast Separations and Development of Geopolymer Based Base stable Stationary Phase Media written by Rasangi Madhumali Wimalasinghe K.K.D.G. and published by . This book was released on 2019 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis consists of two sections. In the first section fundamentals of ultrafast separations is discussed. Ultrafast chromatography is an emerging area of separation science due to its applicability in high-throughput separations and purifications. State of the art superficially porous particles packed short and ultrashort columns are utilized to obtain the amenable speed and chromatographic efficiency required in ultrafast chromatography. Modifications to state of the art HPLC and UHPLC instrumentation required in cases where ultrafast separations are needed. Sub-second liquid chromatographic separations and ultrafast separations of biomolecules and complex mixtures are demonstrated. Fundamentals behind the analytical chromatographic column packing are discussed as efficiently packed columns are necessary in ultrafast chromatography. Secondly, first reported utilization of geopolymers in liquid chromatography is discussed. A simple synthesis route has been proposed, and complete characterization of porous geopolymer particles has been performed using various characterization techniques. Geopolymer stationary phases have been successfully utilized in normal phase chromatography and hydrophilic interaction liquid chromatography (HILIC). Further, its HILIC characteristics are compared with other existing HILIC phases. This dissertation will be a resource to understand the fundamentals of ultrafast separations and utilization of geopolymers in the field of separation sciences.
Download or read book Synthesis and Characterization of Stationary Phases for Reversed phase Liquid Chromatography written by Dale Allen Shoemaker and published by . This book was released on 1992 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of HPLC Stationary Phases with Unique Selectivities and Introduction of Molecular Rotational Resonance Spectroscopy in Gas Chromatography written by Nimisha Thakur and published by . This book was released on 2021 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis contributes to advancing liquid and gas chromatography by introducing new stationary phases for HPLC and a new hyphenated GC technique. In the first section, new pH stable stationary phases based on geopolymers are presented for applications in liquid chromatography. The first-ever synthesis of micron-sized spherical particles of geopolymers, customized to be used as HPLC stationary phases, is reported. Complete material characterization of geopolymers using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, laser diffraction, and porosimetry is shown. The chromatographic evaluation of geopolymers is done by comparing parameters such as hydrophilicity, ion exchange selectivity, efficiency, hydrolytic stability, and pH stability with silica stationary phases. Geopolymers are successfully employed for separations of various classes of compounds using hydrophilic interaction liquid chromatography (HILIC) and normal phase chromatography. Furthermore, geopolymer monoliths are synthesized by inducing higher and interconnected porosity in their otherwise impermeable structure to advance their applications in fields like separation science, catalysis, and drug delivery. This thesis also presents chemical modifications of original geopolymer particles to extend the applications in separation and adsorption sciences. Firstly, transition metal-free geopolymer microspheres are introduced as a second-generation geopolymer stationary phase, showcasing the improvements in the chromatographic performance (particularly peak shapes). Secondly, barium exchanged geopolymers are proposed as new HILIC stationary phases specially developed for separations of compounds with acidic functional groups like carboxylates, sulfonates, and sulfates. Thirdly, iron oxide coated geopolymer microspheres are demonstrated as cost-effective and porous adsorbents for arsenate, arsenite, monomethyl arsenate, and dimethyl arsenate. The second section of this thesis introduces the concept of hyphenation of gas chromatography (GC) with molecular rotational resonance spectroscopy (GC-MRR). The power of MRR lies in its ability to discern the slightest change in the mass and/or molecular geometry in a molecule resulting in distinct rotational spectra. The unique abilities of the GC-MRR are demonstrated by the separation and quantification of a series of 24 isotopologues and isotopomers of five organic compounds. Natural isotopic abundances of mixtures of compounds containing chlorine, bromine, and sulfur heteroatoms are easily determined.
Download or read book Synthesis and Characterization of New Bonded Stationary Phases for HPLC written by Deepika Janga and published by . This book was released on 2004 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis and Characterization of Bonded Stationary Phases in High Performance Liquid Chromatography written by Steven Douglas Fazio and published by . This book was released on 1985 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Temperature Liquid Chromatography written by Thorsten Teutenberg and published by Royal Society of Chemistry. This book was released on 2010-06-03 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-temperature liquid chromatography has attracted much interest in recent years but has not yet recognized its full potential in the chromatographic community. There is a widespread reluctance in industry to use temperature to speed up the separation process, influence the selectivity of a separation or implement novel detection techniques. However, the technology has now matured and could revolutionize chromatography as we see it today. Better equipment, such as heating systems able to generate faster heating rates, is becoming more readily available. Also, columns based on silica gel, which can withstand higher temperatures for an extended period, are now being introduced. Nevertheless, further technological and methodical efforts are needed to establish the method in a regulated environment like the pharmaceutical industry. This is the only text to cover all the practical aspects, as well as the underlying theoretical principles, of setting up an HPLC system for high temperature operation. It is not intended solely for academics but will also benefit the researcher interested in more practical considerations. The author is a recognized expert and has conducted several studies with partners from industry to validate the method. Many real examples from these studies have been included in the book. The aim is to support practitioners in the creation of their own protocols without the need to rely solely on trial and error. The book starts with a brief definition of high temperature liquid chromatography before going on to cover: system set up; the heating system; mobile phase considerations; suitable stationary phases; method development using temperature programming; analyte stability, and special hyphenation techniques using superheated water as a mobile phase. In each chapter, experimental data is used to illustrate the main statements and the advantages over conventional HPLC are evaluated. The book concludes with a critical outlook on further developments and applications underlining the necessary advances needed to make high temperature HPLC more robust.
Download or read book Handbook of Advanced Chromatography Mass Spectrometry Techniques written by Michal Holcapek and published by Elsevier. This book was released on 2017-09-07 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book Characterization and Development of Novel Stationary Phases for Capillary Electrochromatography written by Maria Kaltcheva and published by . This book was released on 2011 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porous monolithic stationary phases for capillary electrochromatography have shown great potential due to the ability to tune their properties for tailor-made separations by careful selection of the polymerization parameters. However, the final morphological and chemical properties of the column remain difficult to predict. In order to better understand the effects of the relevant variables on column properties and morphology we have significantly streamlined the preparation procedure and investigated an array of variables (temperature, reaction time, porogenic solvent concentration) on the porosity and retention of the columns. Factorial experimental design was implemented to derive models that were able to describe the polymer porosity and the retention of three PAH's as a function of starting reagents and conditions. The current study showed that with a factorial design approach, monolith porosity and chromatography can be reliably tuned by adjusting the porogenic solvent concentration, the polymerization time and reaction temperature. Scanning electron microscopy revealed that the polymerization conditions affected the polymer structure and particle size. Synergistic effects not accessible by the "one variable at time" approach were identified between the temperature and polymerization time and temperature and monomer/porogenic solvent ratio through multivariate analysis. The control of the monolith porosity and chromatographic behaviour will allow future efforts to be focused on creating reproducible, tailor-made monolithic columns with targeted chromatographic properties suitable for the separation of peptides and proteins from biological fluids.
Download or read book Characterization of Stationary Phases for Reversed phase Liquid Chromatography written by Hendrikus Antonius Claessens and published by . This book was released on 1999 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt:
