定量核磁共振碳谱同时测定食用油中甘油三酯的sn-1,3和sn-2脂肪酸含量  

Simultaneous Determination of Fatty Acids at sn-1,3 and sn-2 of Triglyceride in Edible Oils by Quantitative 13C-Nuclear Magnetic Resonance

作　　者：肖坤 龚灿 郭强胜 许旭 XIAO Kun;GONG Can;GUO Qiang-Sheng;XU Xu(School of Chemical and Environmental Engineering,Shanghai Institute of Technology,Shanghai 201418,China)

机构地区：[1]上海应用技术大学化学与环境工程学院,上海201418

出　　处：《分析化学》2020年第6期802-810,I0003,I0004,共11页Chinese Journal of Analytical Chemistry

基　　金：国家自然科学基金项目(No.31671928);上海市自然科学基金项目(No.15ZR1440800)资助。

摘　　要：建立了定量核磁共振碳谱(13C-qNMR)技术测定食用油中特定位置不饱和脂肪酸含量的方法。使用反转门控去耦技术对食用油中的脂肪酸进行位置特异性分析,针对未完全分离的谱峰,比较了直接普通积分、使用不同的洛伦兹/高斯函数比值去卷积积分等数据处理方式对核磁共振碳谱定量结果的影响,选择以洛伦兹-高斯(3:2)的比例,对谱图进行去卷积拟合,提取sn-1,3和sn-2位亚油酸和油酸两种不饱和脂肪酸的定量峰,测定3种食用油中甘油三酯的饱和脂肪酸、sn-1,3位亚油酸、sn-2位亚油酸、sn-1,3位油酸、sn-2位油酸含量分别为:大豆油(16.2%、 27.8%、 24.0%、 15.5%、 7.9%(w/w,下同));玉米油(15.3%、 30.7%、 20.5%、 20.1%、 13.3%);花生油(18.3%、 18.7%、 12.5%、 24.9%、 25.5%)。大豆油中sn-1,3位亚麻酸、sn-2位亚麻酸分别为4.5%和4.0%,玉米油和花生油中未检出亚麻酸。上述结果与1H-qNMR测定的各脂肪酸总量一致。13C-qNMR可对食用油中脂肪酸进行位置特异性分析,无需复杂的样品前处理过程,可区分不饱和脂肪酸的不同位置分布,为在缺乏甘油三酯标样的情况下测量食用油中特定甘油三酯位置异构体成分含量提供了新方法。A 13C-quantitative nuclear magnetic resonance(qNMR) method was established for determination of content of fatty acid at different positions in edible oil. The positional specificity analysis of sn-1,3 and sn-2 in fatty acids in edible oil was performed using reverse-gated decoupling technique. The direct normal integral, deconvolution integral using different Lorentz-Gaussian ratios, and other data processing methods were compared for the analyzing 13C-qNMR unseparated peaks. Then the deconvolution integral with Lorentz-Gauss(3∶2) was selected to extract the quantitative peak areas of two unsaturated fatty acids at sn-1,3 and sn-2, linoleic acid and oleic acid. The content of unsaturated fatty acids in different positions showed that the saturated fatty acids, sn-1 linoleic acid, sn-2 linoleic acid, sn-1,3 oleic acid, sn-2 oleic acid were as follows: soybean oil(16.2%, 27.8%, 24.0%, 15.5%, 7.9%(w/w, the same below));corn oil(15.3%, 30.7%, 20.5%, 20.1%, 13.3%);peanut oil(18.3%, 18.7%, 12.5%, 24.9%, 25.5%). The sn-1,3 linolenic acid, sn-2 linolenic acid in soybean oil were 4.5% and 4.1%, respectively, but were undetectable in corn oil and peanut oil. The result was in accordance with content of total linoleic acid and total oleic acid detected by above 1H-qNMR method. 13C-qNMR can be applied to distinguish the location and distribution of unsaturated fatty acids with easy sample preparation and flexible operation, providing a method for quantifying the specific triglyceride positional isomer component in edible oil without its standard sample.

关 键 词：定量核磁共振波谱法 核磁共振碳谱 食用油 脂肪酸 位置异构体 

分 类 号：O657.2[理学—分析化学] TS227[理学—化学]