A GC/MS based method for the thorough analysis of sterols in food

甾醇是一种具有生物活性的脂类化合物，几乎在所有食品样品中都能找到，浓度约为总脂质的1%。这类物质存在于250多种单独的化合物中。然而，可作为参考标准的很少，在现有常规方法的常规分析中可测量的不到20个。在样品分析过程中，许多甾醇被忽略，标记未知或错误。此外，据报道，微量固醇的测定容易出错。该项目的目标是开发一种灵敏的GC/MS方法，可以对食品样品中的所有甾醇进行彻底分析。为此，建立了一个基于Kováts指数的新概念，使用自合成的脂肪酸吡咯烷酯（pyrrolidides）作为参考化合物，结合高灵敏度的GC/MS选择离子监测（SIM）筛选方法，允许分配结构的痕量甾醇（贡献<0.01%脂类）。初步鉴定的甾醇将通过逆流色谱（CCC）和其他方法（氢化，固相萃取）富集/分离，然后通过GC/MS和NMR进行结构研究。将合成几种氘标记化合物，作为定量的内标。所有数据将合并在一个全面的数据库中，使用户能够为不同的目的可靠地确定甾醇。

Sterols are bioactive lipid compounds virtually found in all food samples at concentrations of ~1% of the total lipids. This substance class exists in a variety of over 250 individual compounds. However, very few are available as reference standards, and less than 20 can be measured in routine analysis by existing routine methods. During the analysis of samples, many of the sterols are overlooked, and labelled unknown or wrongly. In addition, determination of minor sterols was reported to be prone to errors. The goal of this project is the development of a sensitive GC/MS method that allows the thorough analysis of all sterols in and from food samples. For this purpose, a new concept based on Kováts indices was developed using self-synthesized fatty acid pyrrolidine esters (pyrrolidides) as reference compounds in combination with a highly sensitive GC/MS selected ion monitoring (SIM) screening method that allows to assign structures to trace sterols (contribution <0.01% to the lipids). Tentatively identified sterols will be enriched/isolated by means of countercurrent chromatography (CCC) and other methods (hydrogenation, solid phase extraction) followed by structure investigation by GC/MS and NMR. Several deuterium labelled compounds will be synthesized for use as internal standards for quantification. All data will be merged in a comprehensive data base that will allow users to determine sterols reliably for different purposes.