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Cis and trans components of lipids: Analysis by 1 H NMR and silver shift reagents
Author(s) -
Agiomyrgianaki Alexia,
Sedman Jacqueline,
Van de Voort Frederik R.,
Dais Photis
Publication year - 2012
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/ejlt.201100348
Subject(s) - degree of unsaturation , chemistry , reagent , allylic rearrangement , double bond , cis–trans isomerism , proton nmr , nmr spectra database , carbon 13 nmr , molecule , spectral line , organic chemistry , catalysis , physics , astronomy
In this study, the methodology of shift reagents was exploited to distinguish cis and trans unsaturation in oils and fats. The differential binding of silver ions (in the form of AgFOD) to cis and trans double bonds allowed the separation of the allylic and olefinic proton signals in the 1 H NMR spectra of mixtures of cis and trans methyl esters of monoene aliphatic acids and unsaturated triacylglycerol mixtures at low frequency spectrometers (300 MHz). Careful integration of the appropriate proton resonances in the recorded quantitative 1 H NMR spectra afforded percentage concentrations in very good agreement with the actual values. This 1 H NMR methodology was validated by analyzing AOCS Laboratory Proficiency Program GC samples containing various percentages of saturated, cis ‐mono unsaturated, and cis ‐polyunsaturated fat as well as trans content. This fast and relatively low‐cost NMR methodology could be used on line for obtaining nutrition labeling compositional data (NLCD) required for fat‐containing food products. Attempts to differentiate lipid molecules with different degree of unsaturation and positional distribution of cis double bonds were unsuccessful.