Lipid Profile Determination by Direct Infusion ESI-MS and Fatty Acid Composition by GC-FID in Human Milk Pools by Folch and Creamatocrit Methods

Human milk (HM) is extremely important to the baby, containing a varied and balanced range of nutrients fundamental to the ideal development of the newborn. Among these nutrients, HM lipids provide 40-60% of the energy. In HM banks, the creamatocrit method is employed as a quick and solvent-free tool, however, since Folch methodology is considered reference for lipid extraction, this study compared the fatty acid (FA) composition and the lipid profile by gas chromatography with flame ionization detector (GC-FID) and direct infusion by electrospray ionization mass spectrometry (DI-ESI-MS) in pools of different HM phases, obtained from Folch and creamatocrit methods, in order to elucidate which method provides better information about HM lipids. Lipid compositon results by Folch were superior to the results obtained by creamatocrit in HM pools investigated. It means, the lipid profiles of all HM pools were more intense, and the number of FA identified by Folch was also higher in comparison to the creamatocrit method (21 and 6 FAs, respectively). GC-FID analysis in combination with principal component analysis (PCA) divided the methods, confirming a greater contribution of the Folch method. Therefore, Folch methodology revealed an effective lipid extraction in comparison to creamatocrit method.

人乳（Human Milk, HM）对婴儿极为重要，其含有种类多样且均衡的营养素，这些营养素是新生儿理想生长发育的必需基础。其中，人乳脂质可提供40%~60%的机体能量。在人乳库中，乳脂计法（crematocrit method）常作为快速无溶剂检测手段被使用，但福氏萃取法（Folch methodology）被公认为脂质提取的参考标准方法。本研究采用火焰离子化检测器气相色谱法（GC-FID）与电喷雾电离质谱直接进样法（DI-ESI-MS），分别分析经福氏萃取法与乳脂计法获取的不同人乳组分混合样的脂肪酸（FA）组成及脂质谱，以阐明哪种方法能更精准地反映人乳脂质的相关信息。研究结果表明，在本次研究所涉及的人乳混合样中，福氏萃取法得到的脂质组成结果优于乳脂计法。具体表现为：所有人乳混合样的脂质谱信号更强，且福氏萃取法鉴定出的脂肪酸数量也多于乳脂计法（分别为21种与6种）。结合主成分分析（PCA）的GC-FID分析可有效区分两种实验方法，证实福氏萃取法对脂质提取的贡献更为显著。综上，相较于乳脂计法，福氏萃取法可实现更高效的人乳脂质提取。