Determination of stigmasterol and cholesterol oxides using atmospheric pressure chemical ionization liquid chromatography/mass spectrometry

Validation of a gas chromatography–mass spectrometry method for the analysis of sterol oxidation products in serum

“…There are not POPs standards commercially available, so the analytical methods for POPs have been carried out using commercial COPs as model substances, assuming that the ionization efficiency of both types of molecules and their behaviour is very similar, as they have similar structures. Response factors obtained for COPs are also valid for quantitative work regarding POPs [34][35][36].…”

Sitosterol Thermo‐oxidative Degradation Leads to the Formation of Dimers, Trimers and Oligomers: A Study Using Combined Size Exclusion Chromatography/Mass Spectrometry

“…Overall, fragmentation of monomer ions indicates the presence of two oxygen molecules, indicative of sterol oxides. Kemmo et al [24,25] also established similar fragmentation and type of ions during the analysis of different types of sterol oxides.…”

“…The nature of the oxygenated FS monomer must at this point remain highly speculative. It is believed that sterol oxidation is initiated by abstraction of a hydrogen atom to generate a free radical, which in turn reacts with oxygen forming next generation of radicals and sterol 7-hydroperoxides [11,24]. It seems likely that the A/B sterol rings are involved in forming the monomer and that reactive hydroperoxy radicals would be involved in further reactions to give oligomers and other products.…”

“…In this way, oligomers up to tetramers of triolein with and without additional oxygen atoms were observed. A similar technique was applied for the separation and identification of cholesterol and phytosterol oxides [24,25]. In this paper we present for the first time to our knowledge, the mass spectra of phytosterol oligomers and proposing fragmentation of these molecules.…”

Detection and confirmation of serum lipid biomarkers for preeclampsia using direct infusion mass spectrometry

“…MS 2 studies were performed on all 23 confi rmed serum lipid biomarkers. This provided lipid classes; exact mass studies ( 27,28 ). The lipid ion peak at m/z 383.3 has been identifi ed to be dehydrated 7-ketocholestrol in a number of published studies involving human blood samples (29)(30)(31); although, we recognize that oxidation of cholesterol at some other position is possible and would result in similar fragmentation.…”