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

甾醇是一种生物活性脂类化合物，几乎存在于所有食品样品中，其浓度约为总脂的1%。这类物质存在于250多种单独的化合物中。然而，作为参考标准的很少，只有不到20个可以用现有的常规方法在常规分析中进行测量。在样品分析过程中，许多甾醇被忽视，并被贴上未知或错误的标签。此外，据报道，次要甾醇的测定容易出错。该项目的目标是开发一种灵敏的GC/MS方法，使其能够彻底分析食品样品中的所有甾醇。为此，开发了一个基于Kováts指数的新概念，使用自行合成的脂肪酸吡咯烷酯(吡咯烷)作为参比化合物，结合高灵敏的GC/MS选择离子监测(SIM)筛选方法，允许对痕量甾醇进行结构分配(对脂类的贡献率为0.01%)。初步鉴定的甾醇将通过逆流色谱(CCC)和其他方法(加氢、固相萃取)进行浓缩/分离，然后通过GC/MS和核磁共振进行结构研究。将合成几种标记了重氢的化合物，作为定量的内标。所有数据将被合并到一个全面的数据库中，使用户能够针对不同的目的可靠地测定甾醇。

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.