Carbon-13 nuclear magnetic resonance quantitation

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). 

Currently, there are no accurate methods available for quantifying the aliphatic bridges in the coal macromolecule. Quantitative nature of the application of infrared (IR) spectroscopy is limited to certain general types of functional groups or bond types. Nuclear magnetic resonance spectroscopy, despite the success of dipolar dephasing techniques to decipher the extent of substitution on carbon atoms, is still inadequate to distinguish distinct structural entities . 

For simple poly(a-olefins) of practical importance, the chain stereostructure can be quantitatively determined at least at the stereotriad level [1], Longer configurational sequences can be observed by nuclear magnetic resonance, particularly using larger magnetic fields or 13C NMR spectroscopy or both. The chemical shifts due to CH3,CH2 and CH carbons are widely spaced. It is mainly the chemical shift of the pendant CH3 group carbon that is utilised for sequential analysis. 

Gerstein BC, Dybowski CR (1985) Transient techniques in NMR of solids an introduction to theory and practice Academic Press, Orlando, 295 pp Hatcher PG (1987) Chemical structural studies of natural lignin by dipolar dephased solid-state nC nuclear magnetic resonance Org Geochem 11 31-39 Hatfield GR, Maciel GE, Erbatur O, Erbatur G (1987) Qualitative and quantitative analysis of solid lignin samples by carbon-13 nuclear magnetic resonance spectrometry Anal Chem 59 172-179... 

Mao J.-D., Hu W.-G., Schmidt-Rohr K., Davies G., Ghabbour E. A., and Xing B. (2000) Quantitative characterization of humic substances by solid-state carbon-13 nuclear magnetic resonance. Soil Sci. Soc. Am. J. 64, 873-884. 

NMR. Quantitative liquid-state carbon-13 nuclear magnetic resonance ( 3c NMR) spectra were recorded for humic and fulvic acid from Como Creek foam and for stream and foam fulvic- and humic- acid samples from the Suwannee River at the U.S. Geological Survey, laboratory in Arvada, CO. C NMR could not be performed on other humic substances due to insufficient sample or instrument availability. The acquisition parameters used were as follows C NMR spectra were recorded on a Varian XL-300 NMR spectrometer at 75 MHz. Each sample (200 mg of freeze-dried material) was dissolved in deuterated water and deuterated sodium hydroxide was added to ensure solution a total solution volume of approximately 6 to 7 mL. Spectra were recorded using a 30,000 Hz spectral window, a 45 pulse width, a 0.199 second acquisition time, and a pulse delay of 10 seconds for quantitative spectra. The number of transients was 10,000, and line broadening was 50 Hz. 

Hu, S., Liu, H., Yu, B., Cao, C. and H, S.Z. (2001) Investigation on quantitative relationship between chemical shift of carbon-13 nuclear magnetic resonance spectra and molecular topological structure based on a novel atomic distance-edge vector (ADEV). /. Chemom., 15, 427-438. 

Carbon 13 nuclear magnetic resonance can be used quantitatively in analyses of polymers to measure conveniently comonomer concentrations, average sequence lengths, run numbers and comonomer triad distributions. 

Wollenberg, K. F. (1990) Quantitative high resolution nuclear magnetic resonance of the olefinic and carbonyl carbons of edible vegetable oils. JAOCS, 67, (8), 487-94. 

Other methods which can also be apphed include electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR). Information on the charge carrier concentration and their mobihty can be obtained by EPR thus rendering a deeper insight into the conduction behavior of carbons [14]. NMR furthermore provides structural information, such as quantitative sp /sp ratio comparable to Raman and XPS. 

The usefulness of XPS in the study of the surface chemistry of carbonaceous materials is well established [120-123]. It is significant, however, that in 1994, while reviewing some aspects of the surface chemistry of carbon blacks and other carbons (in particular, active carbons), Boehm [48] devoted only a few lines to XPS and argued that XPS is not very useful for quantitative determinations. The selected examples included here are meant to give the reader an idea of the use of XPS in the last decade, often in combination with other methods such as FTIR and TPD, and more recently with solid-state nuclear magnetic resonance (NMR), for both qualitative and quantitative characterization of the surface chemistry (i.e., functional groups) either of raw carbonaceous materials or after their treatment (e.g., activation, thermal or chemical treatment, and pyrolysis). 

Lin RC, Davis EJ (1974) Malic enzymes of rabbit heart mitochondria. J Biol Chem 249 3867-3875 London RE, Kollman VH, Matwiyoff NA (1975a) The quantitative analysis of carbon-carbon coupling in the C nuclear magnetic resonance spectra of molecules biosynthesized from " C enriched precusors. J Am Chem Soc 97 3565-3573 London RE, Matwiyoff NA, Kollman VH (1975b) Differential nuclear overhauser enhancement for i C siglet and multiplet resonances of a carboxyl carbon. J Magn Res 18 555-557... 

Quantitative characterization of humic substances by solid-state carbon-13 nuclear magnetic resonance. 2000 64 873-884. 

Jarman, R.H., Ray, G.J., Standley, R.W., and Zajac, G.W. Determination of bonding in amorphous carbon films A quantitative comparison of core-electron energy-loss spectroscopy and C nuclear magnetic resonance spectroscopy. Appl. Phys. Lett. 1986 49 1065-1067. 

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