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 The Synthesis and Characterization of Reversed Phase Stationary Phases for High Performance Liquid Chromatography written by Karen Wink Barnes and published by . This book was released on 1986 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reversed phase liquid chromatography (RPLC) is a widely used separation technique today. The stationary phase, composed of hydrocarbon moieties chemically bound to a silica support, is commonly prepared by refluxing the silica with a reactive silane in an appropriate solvent. Siloxane bonds, Si-O-Si, are formed. There are limitations to RPLC in that nonhomogeneous surface coverages, detrimental to efficient separations, result from the bonding process, and because the reaction is never complete due to steric restrictions. Also, silica is soluble at high pH values, and the Si-C bond binding the hydrocarbon to the silica is labile at low pH ranges. Thus, the usable pH range for silica stationary phases is 2.5 to 7.5, and often this range is too narrow to allow the separation of a mixture. The use of ultrasonic cavitation to catalyze silane bonding was investigated to dtermine whether the vigorous ultrasonic process would drive reagents into the surface pores and better distribute the hydrocar bonaceous reagent, thereby producing a more efficient stationary phase. Tandem reactions proved that ultrasonic bonding procedures are as effective as the refluxed, and that the chromatographic efficiency of the ultrasonic phases was comparable, if not superior, to the refluxed. Chromatographic tests also indicated the ultrasonic phases were comparable to commercially available phases. The reproducibility of the reactions and the effect of acoustic power and heat were also investigated. A second set of experiments investigated substitution of alumina for silica because the alumina crystalline structure remains intact over a pH range of 2 to 12. A trifunctional modification scheme generating a thick cross-linked hydrocarbon matte was used because the Al-0 bond is susceptible to hydrolysis, which strips the bound hydrocarbons, by polar RP solvents. Five aluminas were bonded and tested for chromatographic utility. Reaction conditions were optimized, and ultrasonic bonding was investigated. It was found that alumina with a sufficiently active surface is modifiable, and that the modified surface is remarkably stable for use with acidic and basic buffers and in neutral, polar solvent mixtures. The chromatographic utility of alumina phases was demonstrated and compared with the silica results.
Download or read book The Synthesis and Characterization of Reversed Phase Stationery Phases for High Performance Liquid Chromatography written by Karen Wink Barnes and published by . This book was released on 1986 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
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 Synthesis and Evaluation of Four Novel Stationary Phases in High Pressure Liquid Chromatography written by Niloofar Salehi and published by . This book was released on 2012 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: High pressure liquid chromatography is one of the most frequently used methods for the separation of mixtures. Chemically modified silica hydride stationary phases, due to their unique selectivity and versatility, have been the focus of an increasing number of studies in the past several years. The objective of fabricating stationary phases with dual properties is to achieve separation of both polar and non-polar components in a single analysis. Due to an increasing demand in the fields of drug discovery, proteomics, and metabolomics to analyze numerous samples with a wide range of polarities, there is a need for more versatile stationary phases for a wide range of applications. In order to meet the above objective, in this research four novel silica hydride-based columns were synthesized using a hydrosilation procedure. The characterization of each column was done using a series of polar and nonpolar compounds by studying their aqueous normal phase and reversed-phase chromatographic behavior. Under these conditions, it turned out that two columns showed both RP and ANP behaviors. Of the remaining columns, one exhibited ANP behavior only and the other performed only in the reversed-phase mode.
Download or read book Synthesis and Characterization of Liquid Crystal like Stationary Phases for High Performance Liquid Chromatography written by Zhuxu Wang and published by . This book was released on 1995 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis and Characterization of Bonded Zwitterionic Stationary Phases for High Performance Liquid Chromatography written by Louis W. Yu and published by . This book was released on 1987 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis and Characterization of Homopolypeptide Bonded Stationary Phases for Liquid Chromatography written by Barbara Ann Siles and published by . This book was released on 1993 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Surface confined Ionic Liquid Stationary Phases for High Performance Liquid Chromatography written by David S. Van Meter (III.) and published by . This book was released on 2008 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 The HPLC Expert written by Stavros Kromidas and published by John Wiley & Sons. This book was released on 2016-08-08 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rapid development of HPLC instrumentation and technology opens numerous possibilities - and entails new questions. Which column should I choose to obtain best results, which gradient fits to my analytical problem, what are recent and promising trends in detection techniques, what is state of the art regarding LC-MS coupling? All these questions are answered by experts in ten self-contained chapters. Besides these more hardware-related and technical chapters, further related areas of interest are covered: Comparison of recent chromatographic data systems and integration strategies, smart documentation, efficient information search in internet, and tips for a successful FDA inspection. This practical approach offers in a condensed manner recent trends and hints, and will also display the advanced reader mistakes and errors he was not aware of so far.
Download or read book The Synthesis and Characterization of Endcapped Silica Hydride Stationary Phase written by Prema Gangadhara and published by . This book was released on 2011 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: The silanization/hydrosilation process was developed to overcome some of the drawbacks associated with the use of organosilane reagents for the synthesis of high pressure liquid chromatography (HPLC) stationary phases. The first step is called silanization, in which silica or other oxides react with triethoxysilane (TES), resulting in the formation of a silica hydride surface. Endcapping the stationary phase using trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDS) eliminates the unreacted and accessible silanols on the silica hydride intermediate. This research employed the modification of bare silica to silica hydride via silanization. Endcapping after silanization eliminated accessible and unreacted silanols. Endcapping was confirmed by using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The stationary phase was characterized for its hydrophobicity and silanophilicity properties. The effectiveness of the stationary phase was determined for its aqueous normal phase and reversed-phase chromatographic behavior. The performance was compared with the performance of C8 silica hydride column under similar conditions. This research confirmed that endcapped columns could be used in the aqueous normal phase and reversed-phase modes. Endcapping increased the hydrophobicity of the surface, which in turn increased the efficiency of separation for nonpolar solutes.
Download or read book Handbook of HPLC written by Danilo Corradini and published by CRC Press. This book was released on 2011-01-03 with total page 1018 pages. Available in PDF, EPUB and Kindle. Book excerpt: Delineating its usage in separation, purification and detection processes across a variety of disciplines, from industry to applied research, this work discusses the principles, techniques and instrumentation involving HPLC within a detailed framework. Over 100 tables present previously scattered experimental data.
Download or read book Synthesis and Characterization of HPLC Stationary Phases Using 4 tert butylcalix n arenes written by Rhonda Sue Hirschl and published by . This book was released on 1998 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: HPLC stationary phases of various types are always in demand. The evolution of stationary phases is continuous because of the widely applied techniques of HPLC. The work presented here is a method used to synthesize new stationary phases. The method is based on typical silane chemistry and uses silica as the support material for attachment of 4-t-butylcalix[n]arenes to the surface of the silica. In addition to evaluating the behavior of different calixarenes, different silica pore sizes were also examined. hromatographic studies include reversed phase behavior, and the formation of host/guest complexes. Spectrometric studies include solid state NMR and fluorescence.
Download or read book Synthesis Structural Characterization and Chromatographic Evaluation of Silica Hydride based Perfluorinated Stationary Phase written by Harshada Natekar and published by . This book was released on 2015 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silica hydride based stationary phases have demonstrated unique selectivity and specificity for small sized polar molecules. The weakly hydrophobic nature of silica hydride is thought to be the key reason for its remarkable retention capabilities. Traditional stationary phases bonded with fluorine moieties have also exhibited enhanced retention of small polar molecules. In this research, a perfluorinated silica hydride stationary phase was synthesized by hydrosilation and silanization procedures. Chromatographic characterization of the newly packed column was carried out by a large number of retention studies. The separation capabilities of the column were evaluated in both the aqueous normal-phase (ANP) and reversed-phase (RP) modes. The perfluorinated silica hydride based column showed remarkable retention ability for RP and ANP modes of separation. Hydrophilic molecules were strongly retained in the ANP mode and hydrophobic molecules were retained in the RP mode. Effect of varying pH of mobile phase on the retention time was summarized. Use of acetone as non-polar solvent was demonstrated. In the conclusion, silica hydride based perfluorinated stationary phase successfully exhibited dual retention capability for polar and non-polar analytes.
Download or read book Software assisted Method Development in High Performance Liquid Chromatography written by Szabolcs Fekete and published by Wspc (Europe). This book was released on 2018-07 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook gives a general overview of the possibilities in recent developments in chromatographic retention modeling. As a result of the latest developments in modeling software, several new features are now accessible, opening a new level in HPLC method development. Many of these current possibilities in software assisted liquid chromatographic method modeling for analytical purposes are presented. Several modes of chromatography, including Reversed-Phase Liquid Chromatography (RPLC), Ion Exchange Chromatography (IEX), Hydrophobic Interaction Chromatography (HIC), and Hydrophilic Interaction Liquid Chromatography (HILIC) are explained in detail. For all these chromatographic modes, the most important variables for tuning retention and selectivity are exposed. Beside the industrial and practical benefits of retention modeling, the possibilities in teaching and education are also illustrated. Finally, numerous representative industrial examples are shown, to highlight the benefits, time and cost savings offered by state-of-the-art software assisted HPLC method development.
