Solid-state NMR and FT IR Studies on Chromatographic Column Materials PDF Download
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Author: Gokulakrishnan Srinivasan
Publisher:
ISBN: 9783832510565
Category :
Languages : en
Pages : 0
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Book Description
The development of alkyl bonded stationary phases is one of the major factors, which lead to the growth of reversed-phase high performance liquid chromatography as the most popular mode of high-performance liquid chromatography. In such materials, the conformational order of the alkyl chain moieties is expected to be a major source for the efficiency and selectivity during chromatographic separations. Describing the alkyl chain conformational order on the molecular level is thus crucial for the understanding of such materials function in their respective chromatographic applications. In the present work FT IR and solid-state NMR spectroscopic techniques are employed to examine the conformational order and mobility of alkyl chain segments chemically attached to solid surfaces. The influence of the different solid supports, pressure, surface coverage, synthetic routes and solvents over the wider temperature range on the conformational order of the alkyl chains have been examined. Inspection of the FT IR data for the C30 SAMs reveals that the solid substrate plays a vital role for the actual conformational state of the attached alkyl chains. On investigating commercial DiamondBond-C18 phases, it is found that alkyl chains tethered to the graphite layer, exhibit a higher conformational order than those in conventional column materials. A comparative study reveals that C18 alkyl modified silica gels with higher surface coverage exhibit a higher conformational order compared to one with lower surface coverage. It was found that the C18 phases and solvents interact significantly, resulting in pronounced changes of the alkyl chain conformational order. A decrease in the conformational disorder is found on application of pressure to the stationary phase materials. The results derived from the present studies state that these aforementioned parameters have a strong influence on the conformational order and mobility of alkyl chains tethered to the inorganic metal oxides.
Author: Gokulakrishnan Srinivasan
Publisher:
ISBN: 9783832510565
Category :
Languages : en
Pages : 0
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Book Description
The development of alkyl bonded stationary phases is one of the major factors, which lead to the growth of reversed-phase high performance liquid chromatography as the most popular mode of high-performance liquid chromatography. In such materials, the conformational order of the alkyl chain moieties is expected to be a major source for the efficiency and selectivity during chromatographic separations. Describing the alkyl chain conformational order on the molecular level is thus crucial for the understanding of such materials function in their respective chromatographic applications. In the present work FT IR and solid-state NMR spectroscopic techniques are employed to examine the conformational order and mobility of alkyl chain segments chemically attached to solid surfaces. The influence of the different solid supports, pressure, surface coverage, synthetic routes and solvents over the wider temperature range on the conformational order of the alkyl chains have been examined. Inspection of the FT IR data for the C30 SAMs reveals that the solid substrate plays a vital role for the actual conformational state of the attached alkyl chains. On investigating commercial DiamondBond-C18 phases, it is found that alkyl chains tethered to the graphite layer, exhibit a higher conformational order than those in conventional column materials. A comparative study reveals that C18 alkyl modified silica gels with higher surface coverage exhibit a higher conformational order compared to one with lower surface coverage. It was found that the C18 phases and solvents interact significantly, resulting in pronounced changes of the alkyl chain conformational order. A decrease in the conformational disorder is found on application of pressure to the stationary phase materials. The results derived from the present studies state that these aforementioned parameters have a strong influence on the conformational order and mobility of alkyl chains tethered to the inorganic metal oxides.
Author: Adam Zofka
Publisher: Transportation Research Board
ISBN: 0309129370
Category : Building materials
Languages : en
Pages : 263
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Book Description
"TRB's second Strategic Highway Research Program (SHRP 2) Report S2-R06B-RW-1: Evaluating Applications of Field Spectroscopy Devices to Fingerprint Commonly Used Construction Materials documents evaluation results of practical, portable spectroscopic equipment for in-situ analysis of a wide range of commonly used construction materials. The report also includes proposed American Association of State Highway and Transportation Officials (AASHTO) standards of practice for the analysis of titanium content in traffic paints by X-ray fluorescence and identification of chemical admixtures by attenuated total reflectance. The results of Renewal Project R06B, which produced SHRP 2 Report S2-R06B-RW-1, will be incorporated into an electronic repository for practitioners, known as the NDToolbox, which will provide information regarding recommended technologies for the detection of a particular deterioration. The NDToolbox is in the process of being created by SHRP 2 Renewal Project R06A, which has released SHRP 2 Report S2-R06A-RR-1: Nondestructive Testing to Identify Concrete Bridge Deck Deterioration that identifies nondestructive testing technologies for detecting and characterizing common forms of deterioration in concrete bridge decks. Renewal Project R06B is one of seven follow-on projects to SHRP Renewal Project R06 that produced SHRP 2 Report S2-R06-RW: A Plan for Developing High-Speed, Nondestructive Testing Procedures for Both Design Evaluation and Construction Inspection, which examines existing and emerging nondestructive evaluation (NDE) technologies and their current state of implementation to satisfy the NDE needs for highway renewal"--TRB Website.
Author: Adam Zofka, Maria Chrysochoou, Iliya Yut, and Chad Johnston
Publisher: Transportation Research Board
ISBN: 0309129508
Category :
Languages : en
Pages : 523
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Book Description
This report from the second Strategic Highway Research Program (SHRP 2), which is administered by the Transportation Research Board of the National Academies, presents evaluations of the capability of portable spectroscopy devices to “fingerprint” typical construction materials. The spectroscopy devices are evaluated in laboratory conditions as well as in the field to verify material-testing method combinations found successful. The report also documents simple, easy-to-use nondestructive testing procedures for use in the field to ensure quality construction.
Author: Phyllis R. Brown
Publisher: CRC Press
ISBN: 9780824700188
Category : Science
Languages : en
Pages : 682
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Book Description
"Volume 40 presents an authoritative selection of the best and most up-to-date research findings in separation science. Surveys recent developments in high performance-liquid (HPLC), reversed-phase liquid (RPLC), countercurrent (CCC), and micellar electrokinetic chromatography (MEKC)."
Author: Qian Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 196
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Book Description
The development of new chromatographic materials is a very active field within separation sciences providing improved efficiency for current separation methods and allowing the realization of new ones. The work presented in this dissertation focuses on the development of two new chromatographic materials: a stationary phase based on surface confined ionic liquids and hafnia support monolithic columns for chromatography. Silica particles were chemically modified with methoxysilane derivatives: 1-methyl-3-(trimethoxysilylpropyl)imidazolium bromide and 1-butyl-3-(trimethoxysilylpropyl)imidazolium bromide and used as the stationary phase for HPLC. The modified silica was characterized by thermogravimetric analysis (TGA) and NMR spectroscopy. The ionic liquid moiety was predominantly attached to the silica surface through two silanoxane bonds of the silane derivative. Columns packed with the modified silica material were tested under HPLC conditions. Evaluation of the stationary phase for HPLC was performed using aromatic carboxylic acids as model compounds. The separation mechanism appears to involve multiple interactions including ion exchange, hydrophobic interaction, and other electrostatic interactions. A monolithic column consists of a porous structure inside of a tube (or channel) that forms a continuous bed of chromatographic material. These type of columns present an alternative to packed columns due to their high permeability, absence of frits to confine the packing material, and ease of fabrication. The most common monoliths are based on silica support, polystyrene or polymethacrylate polymeric structures, or acrylamide gels. A new type of monolithic structures based on hafnium oxide (i.e., hafnia) was synthesized using a sol-gel process. The processing reactions and conditions were studied using different analytical methodologies (i.e., pH measurement, FTIR and NMR spectroscopy), in an effort to understand the critical parameters leading to the hafnia monolithic structure. This would allow control of the synthetic conditions to provide materials with desired physicochemical characteristics that can have an impact on chromatographic performance. To understand the sol-gel process in the solution phase, a 177 Hf NMR method was developed to conduct the study of the aqueous chemistry of Hf(IV); to the best of our knowledge, this is the first observation of the 177 Hf NMR signal. Characterization of the hafnia monolithic structure was also performed using TGA, fluorescence spectroscopy and XRD.
Author: National Institute of Standards and Technology (U.S.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 398
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Book Description
Author: U A Th Brinkman
Publisher: Elsevier
ISBN: 1483274705
Category : Science
Languages : en
Pages : 381
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Book Description
TRAC: Trends in Analytical Chemistry, Volume 10 presents relevant topics in global analytical chemistry research. This book discusses the potential of flow injection analysis for water quality monitoring. Organized into 27 parts encompassing 67 chapters, this book begins with an overview of the amount of published information on analytical chemistry research. This text then examines the analytical technique in the electrophoretic separations in narrow bore tubes, which is capable of rapid, high-resolution separations of water-soluble components in small sample volumes. Other chapters consider the application of polynomial and B-spline interpolation to the description of cyclic voltammetric features. This book discusses as well the methods used to investigate the properties of ceramic high-transition-temperature superconductors. The final chapter deals with the importance of monitoring and protecting the environment based on measurement campaigns. This book is a valuable resource for analytical chemists, environmental chemists, and biochemists. Pharmacologists, scientists, students, researcher workers, and other practitioners will also find this book useful.
Author:
Publisher:
ISBN:
Category : Fossil fuels
Languages : en
Pages : 808
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Book Description
Author: United States. National Bureau of Standards
Publisher:
ISBN:
Category :
Languages : en
Pages : 396
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Book Description
Author: Amitava Mukherjee
Publisher: BoD – Books on Demand
ISBN: 9533070250
Category : Medical
Languages : en
Pages : 546
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Book Description
Nature’s evolution has led to the introduction of highly efficient biological mechanisms. Imitating these mechanisms offers an enormous potential for the improvement of our day to day life. Ideally, by bio-inspiration we can get a better view of nature’s capability while studying its models and adapting it for our benefit. This book takes us into the interesting world of biomimetics and describes various arenas where the technology is applied. The 25 chapters covered in this book disclose recent advances and new ideas in promoting the mechanism and applications of biomimetics.
