Miss Alexandra Agiomyrgianaki, a graduate student of the NMR Laboratory of the Chemistry Department was the recipient of the prestigious AOCS Analytical Division Student Award for 2012 for her work in the analysis cis/trans lipids by 1H NMR. According to AOCS, this award recognizes outstanding graduate student in the field of lipid analytical chemistry.
Cis and trans components of lipids. Analysis by 1H NMR and silver shift reagents
A. Agiomyrgianaki, J. Sedman, F. R. Van de Voort, and P, Dais Eur. J. Lipid Sci. Technol. 2012, 114, 504–509
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 1H 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 1H NMR spectra afforded percentage concentrations in very good agreement with the actual values. The 1H NMR methodology was validated by analyzing AOCS Laboratory Proficiency Program GC samples containing various percentages of saturated, cis-monounsaturated, and cis-polyunsaturated fat as well as trans content. This fast and the 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.