Download or read book The Methylene Selectivity of Simple Organic Ions in Reversed phase Liquid Chromatography written by Dongmei Wu and published by . This book was released on 1992 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Liquid Chromatography written by M.C. García-Álvarez-Coque and published by Elsevier Inc. Chapters. This book was released on 2013-01-08 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: The addition of reagents to an RPLC mobile phase enables the separation of ionizable compounds, inorganic anions, and metal ions using conventional instrumentation, silica-based materials, and hydro-organic mixtures, thanks to a variety of secondary equilibria. This gives rise to several chromatographic modes, whose main features are outlined in this chapter. The effect of the mobile phase pH on the retention of ionizable compounds is described, together with the recommended experimental practice. The mechanism of adsorption of amphiphilic anions or cations on the stationary phase to attract analytes with opposite charge or suppress the silanol activity is discussed. Different reagents, such as alkylammonium salts, surfactants (below and above the critical micelle concentration), perfluorinated carboxylate anions, chaotropic ions, and ionic liquids, are considered. The potential of metal chelation for the determination of metal ions and organic compounds is also summarized.

Download or read book The Distribution of Organic Bases in Reverse Phase Liquid Chromatography written by Dudley Shelton Jayasinghe and published by . This book was released on 1989 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: The distribution of hydrophobic ionogenic organic compounds (HIOC's) between aqueous and nonaqueous phases has been investigated. The HIOC's are aniline and methyl substituted anilines. The aqueous phases are methanol-water mixed solvents with varying pH and ionic strength. The nonaqueous phases are silica and alkyl derivatized silica with ethyl- (C-2), octyl- (C-8), and octadecyl- (C-18) silanes. A gas-liquid equilibration method has been developed to determine the Henry's law constants and the activity coefficients of methyl anilines in methanol-water mixed solvents. The logarithm of the Henry's law constants vary quadratically with the volume fraction of methanol. The chromatographic study has been performed to investigate the effect of three mobile phase factors, fraction of methanol, pH, and ionic strength, on the retention of methyl anilines on different stationary phases. The logarithm of mass distribution ratios, log k's, of methyl anilines vary linearly with the volume fraction of methanol. The ratios of H / k' of methyl anilines increase with increase in methanol in the mobile phase, indicating an increase in the activity coefficients in the stationary phases. This observation is found to be true for different methyl anilines in different stationary phases. A partition model is presented to describe the effect of pH and ionic strength on the retention of HIOC's in the mobile phase. The variation in log k' among neutral and ionic methyl anilines can be explained by linear free energy relationships. Equations are established to predict retention of neutral or ionized methyl anilines from their octanol-water partition coefficients at any methanol content in the mobile phase. Acid dissociation constants of methyl anilines determined from the dependence of log k' on pH are in close agrement with those determined by potentiometric titrations. The effect of ionic strength on the retention of both neutral and ionic species of methyl anilines is negligible. That is, the contribution from electrostatic energy and salting out effect are not significant. The chromatographic study is extended to study the retention of methyl anilines on silica as a function of pH and methanol at a constant ionic strength. The dependence of retention on pH is qualitatively interpreted from an ion exchange reaction between the dissociated silanol groups in the surface and the ionized methyl anilines. The effect of methanol on the retention of methyl anilines and of pyridine on silica is described by a quadratic relationship between the log k' and volume fraction of methanol.

Download or read book Studies on Reversed phase Ion pair Chromatography with a Dynamically Coated Adsorbent written by Monika Johansson and published by . This book was released on 1981 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reversed Phase High Performance Liquid Chromatography written by Ante M. Krstulovic and published by . This book was released on 1982-05-04 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive problem-solving approach to reversed-phase high-performance liquid chromatography covering the theoretical aspects and practical information needed in diverse areas of research. Also reviews RPLC applications in the biomedical/biochemical field.

Download or read book How to Use Reverse phase HPLC written by Gábor Szepesi and published by Wiley-VCH. This book was released on 1992 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the though that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemi nation. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 37 (thesis year 1992) a total of 12,549 thesis titles from 25 Canadian and 153 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 37 reports theses submitted in 1992, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.

Download or read book Use of Metal Ions and Other Mobile Phase Additives for Selective Separations in Reversed phase High Performance Liquid Chromatography written by King Cheng Lee and published by . This book was released on 1982 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Understanding Retention Mechanisms and Adjusting Selectivity of Basic Pharmaceutical Separations by Reversed phase Liquid Chromatography written by Jun Dai and published by . This book was released on 2005 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ion pair Chromatography written by Milton T. W. Hearn and published by . This book was released on 1985 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Essentials in Modern HPLC Separations written by Serban C. Moldoveanu and published by Elsevier. This book was released on 2022-06-24 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt: Essentials in Modern HPLC Separations, Second Edition discusses the role of separation in high performance liquid chromatography (HPLC). This new and updated edition systematically presents basic concepts as well as new developments in HPLC. Starting with a description of basic concepts, it provides important guidance for the practical utilization of various HPLC procedures, such as the selection of the HPLC type, proper choice of the chromatographic column, selection of mobile phase and selection of the method of detection, all of which are in correlation with the physico-chemical characteristics of the compounds separated. Every chapter has been carefully reviewed, with several new sections added to bring the book completely up-to-date. Hence, it is a valuable reference for students and professors in chemistry. Provides a thoroughly updated resource, with an entirely new section on Computer-aided Method Development in HPLC and new subsections on miniaturization and automation in HPLC, chemometric aspects of HPLC, green solvent use in HPLC, and more Includes insights into the chromatographic process to find the optimum solution for analyzing complex samples Presents a basis for understanding the utilization of modern HPLC for applications, particularly for the analysis of pharmaceutical, biological, food, beverage and environmental samples

Download or read book Effect of Bonded chain Rigidity on Selectivity in Reversed phase Liquid Chromatography written by June Frances Mullaney and published by . This book was released on 1986 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimization and Methods Development in Reversed Phase High Performance Liquid Chromatography of Ionic Solutes written by Jeffrey Scott Kiel and published by . This book was released on 1984 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Polar embedded Reversed phase Liquid Chromatography Columns and the Temperature Dependence of the Phase Ratio written by Van Quach and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Van't Hoff analysis was used to calculate the transfer enthalpies for four classes of compounds. Enthalpy values for the columns were compared to values reported for conventional alkyl columns and were in agreement. The selection of homologous analyte pairs also allowed for the calculation of and of methylene transfer. The thermodynamic values for methylene selectivity were found to depend significantly on the class of analytes used.

Download or read book Separation Methods in Drug Synthesis and Purification written by Klara Valko and published by Elsevier. This book was released on 2000-10-13 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Separation Methods in Drug Synthesis and Purification

Download or read book Encyclopedia of Lipidomics written by Markus R. Wenk and published by Springer. This book was released on 2018-07-11 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Encyclopedia of Lipidomics will present a complete overview of the field from fundamentals to new discoveries and from concepts, theories and experimental techniques to clinical and industrial applications. The book will develop with the active involvement of a strong editorial board comprised of leaders from the field. The Encyclopedia of Lipidomics intends to be a comprehensive reference resource serving to bridge the gap between clinical and basic science investigators and provide authoritative and digested information to students, scientists as well as non specialists. The book will have an edge over protocol type of works and databases in terms of having wider coverage through rigorous essays on terms, concepts, experimental and analytical techniques, applications and new challenges. Since lipidomics has strong linkages with several of the other biomedical and life sciences disciplines, the proposed encyclopedia will have a wide audience including graduate students, researchers and different levels of scientists in biomedicine, cellular and molecular biology, bioengineering, physiological and biochemistry, and pharmacology across both academia and industry.

Download or read book Masters Theses in the Pure and Applied Sciences written by W. H. Shafer and published by Springer Science & Business Media. This book was released on 1994 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 37 (thesis year 1992) reports a total of 12,549 thesis titles from 25 Canadian and 153 US universities (theses submitted in previous years but only now reported are indicated by the thesis year shown in parenthesis). The organization, like that of past years, consists of thesis titles arrange