Nuclear magnetic resonance spectroscopy composition

Both vapor-phase chromatography and high performance Hquid chromatography, along with nuclear magnetic resonance spectroscopy, have been used for isomer and composition analysis. 

Instmmental methods of analysis provide information about the specific composition and purity of the amines. QuaUtative information about the identity of the product (functional groups present) and quantitative analysis (amount of various components such as nitrile, amide, acid, and deterruination of unsaturation) can be obtained by infrared analysis. Gas chromatography (gc), with a Hquid phase of either Apiezon grease or Carbowax, and high performance Hquid chromatography (hplc), using siHca columns and solvent systems such as isooctane, methyl tert-huty ether, tetrahydrofuran, and methanol, are used for quantitative analysis of fatty amine mixtures. Nuclear magnetic resonance spectroscopy (nmr), both proton ( H) and carbon-13 ( C), which can be used for quaHtative and quantitative analysis, is an important method used to analyze fatty amines (8,81). 

Physical Methods of Examination. Physical methods used to examine coals can be divided into two classes which, in the one case, yield information of a stmctural nature such as the size of the aromatic nuclei, ie, methods such as x-ray diffraction, molar refraction, and calorific value as a function of composition and in the other case indicate the fraction of carbon present in aromatic form, ie, methods such as ir and nuclear magnetic resonance spectroscopies, and density as a function of composition. Some methods used and types of information obtained from them are (41) ... 

Nuclear Magnetic Resonance Spectroscopy Measured in a Chiral Solvent or with a Chiral Solvating Agent. One method of NMR analysis for enantiomer composition is to record the spectra in a chiral environment, such as a chiral solvent or a chiral solvating agent. This method is based on the diastereomeric interaction between the substrate and the chiral environment applied in the analysis. 

Probably, one of the most valuable advances in this field has dealt with the first chemoenzymatic synthesis of the stable isotope-enriched heparin from a uniformly double labelled 13C, 15N /V-acetylheparosan from E. coli K5. Heteronuclear, multidimensional nuclear magnetic resonance spectroscopy was employed to analyze the chemical composition and solution conformation of N-acety 1 hcparosan, the precursors, and heparin. Isotopic enrichment was found to provide well-resolved 13C spectra with the high sensitivity required for conformational studies of these biomolecules. Stable isotope-labelled heparin was indistinguishable from heparin derived from animal tissues and might be employed as a novel tool for studying the interaction of heparin with different receptors.30... 

Hoh, K.P., Ishida, H. and Koenig, J.L. (1990). Silicon-29 solid state nuclear magnetic resonance spectroscopy of composite interfaces. Polym. Composites 11, 121 125. 

The flame retardant mechanism of PC/ABS compositions using bisphenol A bis(diphenyl phosphate) (BDP) and zinc borate have been investigated (54). BDP affects the decomposition of PC/ABS and acts as a flame retardant in both the gas and the condensed phase. The pyrolysis was studied by thermogravimetry coupled with fourier transform infrared spectroscopy (FUR) and nuclear magnetic-resonance spectroscopy. Zinc borate effects an additional hydrolysis of the PC and contributes to a borate network on the residue. 

Swift, R. S., Leonard, R. L., Newman, R. H., and Theng, B. K. G. (1992). Changes in humic acid composition with molecular weight as detected by 13C-nuclear magnetic resonance spectroscopy. Sci. Total Environ. 117-118, 53-61. 

The synthesis of the complex is followed by the most important step of characterization of the complex. The composition and the structural features of both the ligand and complex have to be established before embarking on further studies. There exist many methods by which the composition and structural features of the complexes are studied. Some of the methods are (i) elemental analysis, (ii) X-ray crystallography, (iii) UV-Vis absorption spectra, (iv) infrared spectroscopy, (v) Raman spectroscopy, (vi) thermal methods of analysis such as thermogravimetry, differential thermal analysis, (vii) nuclear magnetic resonance spectroscopy (proton, multinuclear), (viii) electrospray mass spectrometry. Depending upon the complexity of the system, some or all the methods are used in the studies of complexes. 

If you have been working your way through this epic in a more or less linear fashion, then you might have started to ask yourself some fundamental questions such as, How do you know if a vinyl polymer is isotactic, or atactic, or whatever How do you know the composition and sequence distribution of monomers in a copolymer How do you know the molecular weight distribution of a sample This last question will have to wait until we discuss solution properties, but now is a good point to discuss the determination of chain microstructure by spectroscopic methods. The techniques we will discuss, infrared and nuclear magnetic resonance spectroscopy, can do a lot more than probe microstructure, but that would be another book and here we will focus on the basics. 

The solid nature of the excipient may influence the final physical form of the tablet (Byrn et al. 2001), such as a tendency to stick (Schmid et al. 2000), or may induce a polymorphic conversion of the active ingredient (Kitamura et al. 1994). Hence, there have been attempts to develop protocols for the selection of compatible active ingredient-excipient compositions (Serajuddin et al. 1999). For instance, nuclear magnetic resonance spectroscopy has been employed to study the structural changes in epichlorohydrin cross-linked high amylose starch excipient (Shiftan et al. 2000), and has also been used to discriminate between two polymorphs of prednisolone present in tablets with excipients, even at low concentrations (5 per cent w/w) of the active ingredient (Saindon et al. 1993). The characterization of excipients by thermal methods has also been reviewed by Giron (1997). 

Initially an extensive literature search was conducted to identify key world oil shales, i.e., deposits of large size and/or of current interest to potential developers. The resulting information was used to select a few key world oil shales. Thirteen oil shale samples from eight different countries were studied. Samples were acquired from each of the following countries Australia, Brazil, Israel, Sweden, the United States, and Yugoslavia. Two samples were acquired from Morocco and five samples were acquired fr qj the People s Republic of China. Fischer, Ultimate, Rock-Eval, C Nuclear Magnetic Resonance Spectroscopy (NMR), and X-ray Diffraction Mineral analyses were performed on the samples to identify their compositional characteristics. 

I.S. Gribbestad, B. Sitter, S. Lundgren, J. Krane, D. Axelson, Metabolite composition in breast tumors examined by proton nuclear magnetic resonance spectroscopy. Anticancer Res. 19 (1999) 1737. 

Nuclear magnetic resonance spectroscopy I A technique used to study the physical, chemical, and biological properties of matter in this method, scientists subject a molecule to a strong magnet and watch what happens to the atoms that make up the molecule, which provides information about the molecule s composition. 

In this chapter common methods to evaluate chemical properties and phase composition of bioceramic coatings will be briefly described that are available in many laboratories including X-ray diffraction (XRD), vibrational spectroscopy techniques such as infrared (FTIR) and Raman spectroscopy and nuclear magnetic resonance spectroscopy (NMR). These methods provide a host of information on bulk phase composition, degree of crystallinity and crystallite size. Some special techniques including cathodoluminescence serve to reveal intrinsic coating properties that cannot be assessed by conventional analytical techniques, for example to distinguish between amorphous calcium phosphate (ACP) and crystalline calcium phosphates. 

Phase Composition Nuclear Magnetic Resonance Spectroscopy I 325... 

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