Citation: CHENG Shi, WANG Xin, LIU Bao-Lin. Low-field Nuclear Magnetic Resonance Relaxation Characteristics of Fatty Acids with Different Chain Lengths and Degree of Unsaturation. Chinese Journal of Analytical Chemistry, 2018, 46(2): 281-287. doi: 10.11895/j.issn.0253-3820.171056 [复制]
Low-field Nuclear Magnetic Resonance Relaxation Characteristics of Fatty Acids with Different Chain Lengths and Degree of Unsaturation
The chemical structure of fatty acid has a great influence on the relaxation characteristic of lipid. In this work, the low-field nuclear magnetic resonance (LF-NMR) relaxation characteristics of fatty acids with different chain lengths or degree of saturation were investigated firstly, and then the relaxation characteristics of binary or ternary fatty acid mixtures were studied. The result showed that except acetic acid, the T2 relaxation time and T2W decreased as the carbon chain length increased; but as the unsaturated degree increased, these measures all increased. For the binary fatty acid system, the T2 relaxation time and T2W of palmitic acid-oleic acid and stearic acid-oleic acid all increased as oleic acid ratio increased. While for the linoleic acid-oleic acid system, only when the oleic acid ratio was above 40%, the relaxation response changed significantly. For the ternary fatty acid system, the T2 relaxation time of each linoleic acid/oleic acid/stearic acid system increased with the increase of linoleic acid ratio, while the area ratio S21 decreased, and S22 increased. The higher ratio of oleic acid and the change of the peak area ratio were relatively reduced, and the relative increases of T2W changed more slowly.
AOCS Official Method Cd 16b-93; ISO 8292-1