核磁共振氢谱法测定食用油中的脂肪酸含量

    Determination of Fatty Acid Contents in Edible Oils by 1H Nuclear Magnetic Resonance Technology

    • 摘要: 食用油在日常生活中占据重要地位,食用油的脂肪酸组成关乎其营养价值,其检测技术也有很多,核磁共振技术因具有简便迅速的特点,近年来在油脂研究领域的应用逐渐增多。以食用油为研究对象,测定食用油的核磁共振氢谱(1H NMR),利用1H NMR谱图中不同共振峰与脂肪酸中氢核间的对应关系,建立油脂脂肪酸质量分数的1H NMR测定方法。通过计算食用油样品1H NMR谱图中各组共振峰峰面积,确定各不饱和脂肪酸和饱和脂肪酸的物质的量以及饱和脂肪酸甘油三酯的摩尔质量,进而计算油脂中各种脂肪酸的质量分数,并比较了12种油脂(共20个样品)的1H NMR和气相色谱法测定的数据。结果显示,油脂中各种脂肪酸质量分数的1H NMR与气相色谱法测定结果间存在良好的相关性, 决定系数(R2)均接近于1,表明核磁共振技术可替代气相色谱法用于食用油脂肪酸组成的快速测定。

       

      Abstract: Edible oil is very important in daily life, and fatty acid composition of edible oil is related to its nutritional value. Many techniques have been used to determine fatty acid composition of edible oil.Recently, due to its characteristics of convenient and quick operation, nuclear magnetic resonance(NMR) technology has been used more and more in the field of oil research. In this paper, edible oil was used as raw material, and 1H nuclear magnetic resonance (1H NMR) spectrum of the edible oil was determined. The 1H NMR method for determining the mass of fatty acids in edible oil was established by analyzing the relationship between resonance peaks in 1H NMR spectrum with hydrogen nuclei in fatty acids. The molar contents of saturated and unsaturated fatty acids were calculated by using the peak areas of the resonance peaks.The molar mass contentof saturated fatty acid triglycerides was also calculated. Then, the contents of fatty acids in 20 edible oils were calculated. The contents of fatty acids were also determined by gas chromatography (GC) method. The good linear relationship between the results of 1H NMR and GC methods with a correlation coefficient (R2) close to 1 indicated that the 1H NMR technique could be used for the rapid determination of fatty acid composition in edible oils instead of GC.

       

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