Eder K
Institute of Nutrition Physiology, Technical University of Munich, Freising, Germany.
J Chromatogr B Biomed Appl. 1995 Sep 15;671(1-2):113-31. doi: 10.1016/0378-4347(95)00142-6.
The full process of fatty acid methyl ester (FAME) analysis consists of esterification of lipids, and of injection, separation, identification and quantitation of the FAMEs. In order for the required accuracy and precision to be attained, each of these steps has to be optimized. Esterification of lipids can be carried out with several reagents based on acid-catalysed or base-catalysed reactions. The advantages and disadvantages of these reagents are discussed. The most critical step in the gas chromatographic analysis of FAMEs is sample introduction. The classical split injection technique, which is the most widely used technique in the analysis of FAMEs, has the potential disadvantage of boiling-point-dependent sample discrimination. Cold injection of the sample, either on-column or by programmed-temperature vaporization, does not present this problem and should therefore be preferred. Modern, commercially available fused-silica capillary columns offer excellent separation of FAMEs from biological samples. Very polar stationary phases give excellent separation of all FAMEs but have relatively low thermal stability, resulting in long retention times. Non-polar phases have a much greater thermal stability but inferior selectivity. For many analyses, phases of intermediate polarity, which combine the advantages of a relatively high resolution capability with relatively high thermal stability, are the most suitable. FAMEs can be identified by comparison of their retention times with those of individual purified standards or secondary standards based on lipids that have been well characterized in literature. Relative retention times and equivalent chain-length values also provide useful information. FAMEs can be quantitated by peak areas via calibration factors, and absolute concentrations can be determined by adding an internal standard. Among numerous applications in biomedical research, the analysis of fatty acids from body tissues may contribute to the understanding of the link between the dietary intake of fatty acids and the diseases with which these acids are associated.
脂肪酸甲酯（FAME）分析的全过程包括脂质的酯化，以及FAME的进样、分离、鉴定和定量。为了达到所需的准确度和精密度，必须对这些步骤中的每一步进行优化。脂质的酯化可以使用基于酸催化或碱催化反应的几种试剂来进行。讨论了这些试剂的优缺点。FAME气相色谱分析中最关键的步骤是进样。经典的分流进样技术是FAME分析中使用最广泛的技术，但它存在沸点依赖性样品歧视的潜在缺点。冷进样，无论是柱上进样还是程序升温汽化进样，都不存在这个问题，因此应该优先选择。现代市售的熔融石英毛细管柱能很好地分离生物样品中的FAME。极性很强的固定相能很好地分离所有FAME，但热稳定性相对较低，导致保留时间较长。非极性相的热稳定性要高得多，但选择性较差。对于许多分析来说，中等极性的固定相结合了相对较高的分离能力和相对较高的热稳定性的优点，是最合适的。FAME可以通过将其保留时间与单个纯化标准品或基于文献中已充分表征的脂质的二级标准品的保留时间进行比较来鉴定。相对保留时间和等效链长值也提供有用的信息。FAME可以通过校准因子根据峰面积进行定量，绝对浓度可以通过添加内标来确定。在生物医学研究中的众多应用中，对人体组织脂肪酸的分析可能有助于理解脂肪酸的饮食摄入量与这些脂肪酸相关疾病之间的联系。
