Quantitative analysis of alkene/alkane mixtures by carbon-13 nuclear magnetic resonance spectrometry

Solvent shifts and component identification of hydrocarbon mixtures by carbon-13 nuclear magnetic resonance spectrometry

“…Doping will also mask information on naturally occurring metal ions and free radicals in fossil hydrocarbons (6)(7)(8)(9). Steady-state decoupled one-pulse acquisition has been reported several times as an alternative to other methods in quantitative 13C NMR analysis of mixtures (10)(11)(12). Formácek (12) dismissed the idea of doping due to line-broadening effects.…”

“…Room temperature phosphorescence (RTP) is attracting considerable interest among analytical spectroscopists as a practical and efficient tool for trace analysis of organic compounds (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). This technique is based on measuring the phosphorescence emitted, at room temperature, by organic compounds adsorbed on solid substrates or stabilized in special liquid media.…”

Carbon-13 NMR identification of cyclic ethyleneureas important in cellulosic textile finishing

“…This problem can usually be overcome by using the same radio frequency offset and pulse width for the excitation pulse and the same offset and irradiation power for decoupling for each subsequent spectrum. A further source of error has been noted when noise-limiting electrical filters are used (Forsyth et al, 1982). Low-pass filters that minimize fold-in of peaks to the spectral range may act on some of the desired peaks toward the edges of the spectrum and weaken these signals relative to interior signals.…”

“…The power of modern pulse methods for analysis of both simple and complex molecules has already been demonstrated (Benn and Gunther, 1983). Under appropriate conditions, 13C NMR spectroscopy can also be used for quantitative measurements (Forsyth et al, 1982; Levy et al, 1980) in addition to qualitative identifications.…”

Analysis of gas chromatography-mass spectrometry library search results with edited and quantitative 13C nuclear magnetic resonance spectra

“…On-line analysis, as with liquid chromatography/nuclear magnetic resonance (LC/NMR), is at present constrained by mismatch between column capacity and NMR sensitivity (1)(2)(3). As a consequence, NMR analyses of mixtures primarily have been applied to the analysis of bulk properties of samples, e.g., fuels and polymers (4)(5)(6). The method of choice for unknown mixtures, even for nonvolatile compounds that require derivatization reactions, remains gas chromatography/mass spectrometry (GC/MS).…”