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A study of the ozonolysis of model lipids by electrospray ionization mass spectrometry
Author(s) -
Sun Chenxing,
Zhao YuanYuan,
Curtis Jonathan M.
Publication year - 2012
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6183
Subject(s) - chemistry , ozonolysis , triolein , mass spectrometry , electrospray ionization , chromatography , tandem mass spectrometry , chemical ionization , electrospray , organic chemistry , ionization , ion , lipase , enzyme
RATIONALE The ozonolysis of vegetable oils has been proposed as step to functionalise unsaturated lipids for the production of bio‐based chemicals and materials. The observation of ozonolysis products by mass spectrometry will facilitate mechanistic studies that are essential for the further development of industrial processes based on lipid ozonolysis. METHODS Ozonolysis of the model lipids methyl oleate and triolein was performed and samples were taken over a range of reaction times. Ozonlysis products were separated by normal and non‐aqueous reversed‐phase (NARP) liquid chromatography (LC) coupled to electrospray ionization (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) using a hybrid quadrupole‐time of flight instrument. Post‐column addition of ammonium acetate solutions aided ionization. Volatile reaction products were observed using gas chromatography/electron impact mass spectrometry (GC/MS). RESULTS Secondary ozonides, reaction intermediates and previously unreported high molecular weight product dimers were observed as intact molecular ammonium ion adducts under positive ESI. The main fragment ions obtained by MS/MS were from cleavage of the trioxolane group, loss of fatty acyl chain and fragmentation between n‐8 and n‐9 on the fatty acyl chain. The MS/MS spectra and exact mass measurements explain most of the ozonolysis reaction products. CONCLUSIONS LC/MS, LC/MS/MS and GC/MS results demonstrate that the products from the ozonolysis of the model lipids methyl oleate and triolein are consistent with known ozonolysis reaction pathways. LC/MS techniques using non‐aqueous chromatography have permitted the direct observation of mono‐, di‐ and tri‐1,2,4‐triloxanes which are the secondary ozonides formed by the ozonolysis of triolein. It was also shown that intermediates formed during the ozonolysis of triolein can combine to form high molecular weight ozonide dimers. Copyright © 2012 John Wiley & Sons, Ltd.