Preparation of fatty acid methyl esters for gas-chromatographic analysis of marine lipids: Insight studies
Preparation of fatty acid methyl esters for gas-chromatographic analysis of marine lipids: Insight studies
复制标题
DOI：
10.1021/jf048788i
复制
发表时间：
2005-06-29
影响因子：
6.1
通讯作者：
Malcata, FX
中科院分区：
文献类型：
--
作者：
Carvalho, AP;Malcata, FX
生物材料中脂肪酸组成的分析通常是通过适当的衍生化反应将脂肪物质转化为相应的甲酯(FAME)后，用气相色谱进行的。定量衍生化取决于所用催化剂的类型和工艺条件，以及所述样品在反应介质中的溶解度。大多数与衍生化有关的文献都侧重于不同方法之间的差异比较；尽管对于找出特定样品的最佳方法是有用的，但还需要对可能影响FAME制备的每一步的因素进行额外的研究。本工作以鱼肝油和微藻生物量为模型体系，研究了衍生化反应各步骤中各参数的影响。方法的准确性通过与AOCS标准方法的比较来检验，而其重复性则通过(重复的)数据的方差分析来评估。与酸性催化剂相比，碱性催化剂产生的长链不饱和脂肪酸水平较低。其中，乙酰氯和BF3在统计学上是相同的。标准方法包括在使用BF3进行酸性甲基化之前对样品进行碱性处理，与单独使用BF3进行酸性甲基化相比，提供了相同的结果。反应介质的极性在该过程中被发现是最重要的：中间值的极性[例如，通过1：1(v/v)的甲醇与乙醚或甲苯的混合物获得的]提供的多不饱和脂肪酸萃取量在统计上高于通过标准方法获得的多不饱和脂肪酸。
Assays for fatty acid composition in biological materials are commonly carried out by gas chromatography, after conversion of the lipid material into the corresponding methyl esters (FAME) via suitable derivatization reactions. Quantitative derivatization depends on the type of catalyst and processing conditions employed, as well as the solubility of said sample in the reaction medium. Most literature pertinent to derivatization has focused on differential comparison between alternative methods; although useful to find out the best method for a particular sample, additional studies on factors that may affect each step of FAME preparation are urged. In this work, the influence of various parameters in each step of derivatization reactions was studied, using both cod liver oil and microalgal biomass as model systems. The accuracies of said methodologies were tested via comparison with the AOCS standard method, whereas their reproducibility was assessed by analysis of variance of (replicated) data. Alkaline catalysts generated lower levels of long-chain unsaturated FAME than acidic ones. Among these, acetyl chloride and BF3 were statistically equivalent to each other. The standard method, which involves alkaline treatment of samples before acidic methylation with BF3, provided equivalent results when compared with acidic methylation with BF3 alone. Polarity of the reaction medium was found to be of the utmost importance in the process: intermediate values of polarity [e.g., obtained by a 1:1 (v/v) mixture of methanol with diethyl ether or toluene] provided amounts of extracted polyunsaturated fatty acids statistically higher than those obtained via the standard method.