Statistical caculations of C-13 peak assignments of fatty acids containing saturates, oleic and linoleic acid chains in selected vegetable oils and derivation of formula for their chemical shifts analysis using FT NMR spectroscopy
2002
Ali, S.S. | Ali, S. (Islamia Coll., Peshawar (Pakistan). Dept. of Chemistry) | Badshah, S. | Zeb, H.
Carbon-13 FT NMR has been used to analyze fatty acid composition (quantitatively) of vegetable oils. Gated proton decoupling (Suppressed NOE) pulse sequence has been used for proper quantitative integration of C-13 peaks. To reduce spin lattice relaxation time (for quicker analysis) solutions have been prepared in CDCl3 1:3 v/v. Carbon-13 FT NMR has been used to analyze saturated, unsaturated fatty acid composition (quantitatively). In some cases neat oil using external deuterium lock without any solvent (neat sample) has been used. In present studies the different peaks have been used for their statistical analysis and a formula has been derived for their future analysis. It was found that there was little effect of concentration and solvent on the C-13 peaks. The slopes of the data obtained for the oils (palm oil, corn oil, cotton seed oils) are identical, with r-squares equal to one, by taking ppm as regressant and radiofrequency as regressor, whereas the y-intercepts are different for all the oils tested in the above environment.
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