Sterol dimers are the main oxidation products formed during sterols degradation at elevated temperatures. An investigation was carried out to decipher the structure of dimers differing in polarity, formed during β-sitosterol thermo-oxidation. The oxidation products were fractionated using silica gel into non-polar (NP), mid-polar (MP) and polar fractions (P). Oligomers were further separated by size-exclusion chromatography (SEC). Tentative chemical structures of non-polar, mid-polar and polar dimers were identified using Ag(+)/CIS-MS and APCI-MS procedures after on-line RP-HPLC separation. Further structures were verified by NMR and FT-IR spectroscopies.
Keywords: APCI–MS; BDE; CIS–MS; COSY; DEPT; Dimer; Disteryl ether; ELSD; FT-IR; Fourier transform infrared; HMBC; HSQC; NMR; NOESY; SEC; Thermo-oxidation; atmospheric pressure chemical ionisation–mass spectrometry; bond dissociation enthalpy; coordination-ion spray – mass spectrometry; distortionless enhancement by polarization transfer; evaporative light scattering detector; heteronuclear multiple bond correlation; heteronuclear single quantum coherence; nuclear Overhauser enhancement spectroscopy; size-exclusion chromatography; two-dimensional proton correlation spectroscopy; β-Sitosterol.
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