We propose a new analytical method using reverse phase High performance liquid chromatography (HPLC) coupled through an electrospray source with a tandem quadrupole-time-of-flight (ESI-Q-ToF) mass spectrometric detector for the full characterization and quantitation of the different classes of fatty acids and acylglycerols in lipid samples in a single chromatographic run. In this work, we optimized the derivatization reaction for free fatty acids with 2-hydrazinoquinoline, which is a low-cost approach, using a full factorial design. This reaction does not involve transesterification, thus enabling the free fatty acids to be separated and successfully quantified in the presence of mono-, di- and triacylglycerols without altering the whole glyceride profile. This new analytical method provides a full profile of fatty acids, mono-, di- and triglycerides within a relatively short chromatographic run (less than 40 min), with low operating back-pressure (less than 110 bar). The derivatization of the free fatty acids allows their detection in positive mode, with limits of detection in the range of 0.2-1.9 ng/g, and a dynamic range of two orders of magnitude. The figures of merit of the procedure are competitive with respect to the literature. The method was validated by characterizing two different types of olive oils. Free fatty acid content was quantified, and the results are consistent with literature data. The method was applied to the characterization of cow milk and an infant formula, after the precipitation of proteins and phospholipids, and proved suitable for the detection of short chain fatty acids, free fatty acids and glycerides highlighting differences in the composition of the two milks. The proposed procedure improves the current methods for the analysis of acylglyceride based materials, such as olive oil, and proved promising for the characterization of lipids in complex matrices, such as milk.

中文翻译：

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一种测定食品样品中脂肪酸和酰基甘油的新型 HPLC-ESI-Q-ToF 方法

我们提出了一种使用反相高效液相色谱 (HPLC) 通过电喷雾源与串联四极杆飞行时间 (ESI-Q-ToF) 质谱检测器耦合的新分析方法，用于对不同在单次色谱运行中测定脂质样品中的脂肪酸和酰基甘油类别。在这项工作中，我们使用全析因设计优化了游离脂肪酸与 2-肼基喹啉的衍生化反应，这是一种低成本的方法。该反应不涉及酯交换，因此能够在单、二和三酰基甘油存在的情况下分离并成功定量游离脂肪酸，而不会改变整个甘油酯谱。这种新的分析方法提供了脂肪酸、单、在相对较短的色谱运行（小于 40 分钟）内分离甘油二酯和甘油三酯，操作背压低（小于 110 bar）。游离脂肪酸的衍生化允许在阳性模式下进行检测，检测限范围为 0.2-1.9 ng/g，动态范围为两个数量级。该程序的优点与文献相比具有竞争力。该方法通过表征两种不同类型的橄榄油进行了验证。游离脂肪酸含量定量，结果与文献数据一致。该方法在蛋白质和磷脂沉淀后应用于牛奶和婴儿配方奶粉的表征，证明适用于短链脂肪酸的检测，游离脂肪酸和甘油酯突出了两种牛奶成分的差异。所提出的程序改进了当前分析基于酰基甘油酯的材料（如橄榄油）的方法，并被证明有希望用于表征复杂基质（如牛奶）中的脂质。