It was proven that sterols subjected to high-temperature treatment can be concatenated, which results in polymeric structures, e.g., 3β,3'β-disteryl ethers. However, it was also proven that due to increased temperature in oxygen-containing conditions, sterols can undergo various oxidation reactions. This study aimed to prove the existence and perform quantitative analysis of oxidized 3β,3'β-disteryl ethers, which could form during high-temperature treatment of sterol-rich samples. Samples were heated at 180, 200 and 220 °C for 0.5 to 4 h. Quantitative analyses of the oxidized 3β,3'β-disteryl ethers were performed with liquid extraction, solid-phase extraction and liquid chromatography coupled with mass spectrometry. Additionally, to perform this analysis, the appropriate standards of all oxidized 3β,3'β-disteryl ethers were prepared. Eighteen various oxidized 3β,3'β-disteryl ethers (derivatives of 3β,3'β-dicholesteryl ether, 3β,3'β-disitosteryl ether and 3β,3'β-distigmasteryl ether) were prepared. Additionally, the influence of metal compounds on the mechanism of ether formation at high temperatures was investigated.
Keywords: cholesterol; liquid chromatography; mass spectrometry; oxidized 3β,3′β-disteryl ethers; stigmasterol; β-sitosterol.