Dell Pediatric Research Institute, Departments of Pediatrics, Chemistry, and Nutrition, University of Texas at Austin, 1400 Barbara Jordan Boulevard, Austin, Texas 78723, United States.
Department of Food Science, Cornell University, Ithaca, New York 14853, United States.
J Agric Food Chem. 2020 Apr 29;68(17):4973-4980. doi: 10.1021/acs.jafc.0c01075. Epub 2020 Apr 16.
Fatty acid analysis of food lipids containing branched chain fatty acids (BCFAs) are complex because of unavoidable gas chromatography (GC) co-elution. We demonstrate a method for convenient quantitative GC coupled to novel solvent-mediated chemical ionization (CI) mass spectrometry (MS) that enables resolution of co-eluting peaks by mass. The relevant masses yield uniform responses for C normal fatty acids and BCFAs, eliminating the need for rare purified BCFA standards essential for unpredictable responses, as for electron ionization (EI). CI-tandem mass spectrometry analysis of MH yields fragments characteristic of the branch position. Application of the measurement to BCFAs in salami samples demonstrates consistent results for the novel method and EI-MS. A higher proportion of C BCFAs was found in beef compared to milkfat, possibly indicative of fatty acid elongation, endogenous in the beef animal. This method enables straightforward structure elucidation and quantification of food BCFAs and similar chain length normal fatty acids without purified standards.
由于气相色谱（GC）不可避免的共洗脱，含有支链脂肪酸（BCFA）的食物脂质的脂肪酸分析较为复杂。我们展示了一种方便的定量 GC 与新型溶剂介导化学电离（CI）质谱（MS）相结合的方法，通过质量可以分辨共洗脱峰。相关质量对正常 C 脂肪酸和 BCFA 产生均匀的响应，消除了对电子电离（EI）等不可预测响应至关重要的稀有纯 BCFA 标准的需求。通过 MH 的 CI-串联质谱分析，可得到支链位置特征的碎片。该测量方法应用于萨拉米香肠样品中的 BCFA，证明了新方法和 EI-MS 的结果一致。与乳脂肪相比，牛肉中发现 C 支链脂肪酸的比例更高，这可能表明脂肪酸的延长，在牛肉动物中是内源性的。该方法能够在没有纯标准品的情况下，直接阐明和定量食物 BCFA 和类似链长的正常脂肪酸。
