ISBN 9783843956987

978-3-8439-5698-7, Reihe Lebensmittelchemie

Sarah Sabrina Schlag
Novel approaches for the comprehensive GC/MS analysis of 150 sterols in various edible oils

268 Seiten, Dissertation Universität Hohenheim Stuttgart-Hohenheim (2025), Softcover, A5

Zusammenfassung / Abstract

Sterols are a group of triterpene-derived alcohols that contribute significantly to the unsaponifiable matter of vegetable oils and fats. The common feature of the sterols is a 1,2‑cyclopentanophenanthrene backbone, which always has a hydroxyl group at C-3 and an alkyl chain of at least eight carbon atoms at C-17. The various sterols differ in their number and positions of the double bonds in the ring system as well as in the substitution pattern of the backbone and the side chain. The substitution at C-4 plays a special role, with the distinction between 4-desmethyl-, 4‑methyl-, and 4,4-dimethylsterols. Moreover, the structurally related tetra- and pentacyclic triterpenoids are usually analysed together with the true sterols.

Although more than 250 sterols were described in the literature, only a few of them are usually determined in vegetable oils with current routine methods. With the commonly applied method of gas chromatography coupled with flame ionisation detection (GC/FID), most sterols cannot be clearly assigned in the corresponding gas chromatograms. Therefore, comprehensive data on sterols in food and biological samples is currently not available.

Thus, this doctoral thesis reports the development of a gas chromatography coupled with mass spectrometry in selected ion monitoring (GC/MS-SIM) method, which allowed a comprehensive and sensitive detection of known and unknown sterols after silylation. For an accurate assignment of numerous sterols in many different samples, fatty acid pyrrolidides (FAPs) were synthesised and a mixture of them was applied as internal standards (IS) to determine FAP retention indices of silylated sterols. The GC/MS data of the analysed samples was used to determine specific fragment ions and response factors for quantification in GC/MS-SIM mode. Finally, GC/MS data and occurrence data of 150 sterols in 74 sample matrices were summarised in a database.