A First Laboratory Utilizing NMR for Undergraduate Education: Characterization of Edible Fats and Oils by Quantitative 13C NMR
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[1] University of Wisconsin–Madison
University of Wisconsin–Madison
City of Madison, Estados Unidos
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 94, Nº 9, 2017, págs. 1319-1323
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
Quantitative 13C NMR provides a straightforward method of analyzing edible oils in undergraduate chemistry laboratories. 13C spectra are relatively easy to understand, and are much simpler to analyze and workup than corresponding 1H spectra. Average chain length, degree of saturation, and average polyunsaturated fatty acid content of common edible oils are obtained directly using integrals of the proper regions in the 13C 1D spectra. These spectra segue to 2D 1H–13C HSQC experiments that provide an excellent path for students to verify assignments, in particular those associated with polyunsaturated fatty acids. Data acquisition and analysis can be completed in one to two lab sections, although spectrometer scheduling may be necessary for groups of students greater than six. 13C relaxation measurements of common oils are presented that enable accurate quantitative 13C data to be obtained in reasonable amounts of time (30–40 min per sample) on modern 400 MHz NMR spectrometers.
