Abstract
Electron ionization mass spectra of several monounsaturated methyl-branched fatty acid methyl and trimethylsilyl esters were examined. These spectra exhibited some intensive fragment ions, whose formation could be explained after double-bond migration to methylidene position. This preferential migration (substantiated by deuterium labeling) acts significantly in the case of monounsaturated fatty acid methyl and trimethylsilyl esters possessing a methyl branch localized between the penultimate and the C4 positions (relative to the ester group), whatever the position of the double-bond. Allylic cleavage and γ-hydrogen rearrangement of the ionized methylidene group thus formed afforded very interesting fragment ions, which could be particularly useful to determine branching positions of monounsaturated methyl-branched fatty acid methyl and trimethylsilyl esters without additional treatment.
Article PDF
Similar content being viewed by others
References
Christie, W. W. Gas chromatography of lipids—a practical guide. The oily Press: Dundee, 1989, 307.
Pierce, A. E. Silylation of organic Compounds; Pierce Chemical Co: Rockford, 1982; p. 487.
Francis, G. W. Alkylthiolation for the determination of double-bond position in unsaturated fatty acid esters. Chem. Phys. Lipids. 1981, 29, 369–374.
Scribe, P.; Pepe, C.; Barouxis, A.; Fuche, C.; Dagaut, J.; Saliot, A. Determination de la position de l’insaturation des mono-ènes par chromatographie en phase gazeuse capillaire — spectromètrie de masse des dérivés diméthyl-disulfures: application à l’analyse d’un mélange complexe d’alcènes. Analusis. 1990, 18, 284–288.
McCloskey, J. A.; McClelland, M. J. Mass spectra of O-isopropylidene derivatives of unsaturated fatty esters. J. Am. Chem. Soc. 1965, 87, 5090–5093.
Christie, W. W. Gas chromatography-mass spectrometry methods for structural analysis of fatty acids. Lipids. 1998, 33, 343–353.
Hamilton, J. T. G.; Christie, W. W. Mechanisms for ion formation during the electron impact-mass spectrometry of picolinyl ester and 4,4-dimethyloxazoline derivatives of fatty acids. Chem. Phys. Lipids. 2000, 105, 93–104.
Zhang, J. Y.; Yu, Q. T.; Liu, B. N.; Huang, Z. H. Chemical modification in mass spectrometry IV. 2-Alkenyl-4,4-dimethyloxazolines as derivatives for double bond location of long-chain olefinic acids. Biomed. Environ. Mass Spectrom. 1988, 15, 33–44.
Vetter, W.; Walther, W.; Vecchi, M. Pyrrolidides as derivatives for structural analysis of aliphatic and alicyclic fatty acids by mass spectrometry. Helv. Chim. Acta. 1971, 54, 1599–1605.
Shirasaka, N.; Nishi, K.; Shimizu, S. Biosynthesis of furan fatty acids (F-acids) by a marine bacterium, Shewanella putrefaciens. Biochim. Biophys. Acta. 1997, 1346, 253–260.
Kerger, B. D.; Nichols, P. D.; Antworth, C. P.; Sand, W.; Bock, E.; Cox, J. C.; Langworthy, T. A.; White, D. C. Signature fatty acids in the polar lipids of acid-producing Thiobacillus spp.: methoxy, cyclopropyl, α-hydroxy-cyclopropyl and branched and normal monoenoic fatty acids. FEMS Microbiol. Ecol. 1986, 38, 67–77.
Rontani, J.-F.; Christodoulou, S.; Koblizek, M. GC-MS structural characterization of fatty acids from marine aerobic anoxygenic phototrophic bacteria. Lipids. 2005, 40, 97–108.
Grossi, V.; Cravo-Laureau, C.; Méou, A.; Raphel, D.; Garzino, F.; Hirchler-Réa, A. Anaerobic 1-alkene metabolism by the alkane and alkene-degrading sulphate reducer Sulfatibacillum aliphaticivorans strain CV2803. Appl. Environ. Microbiol. 2007, 73, 7882–7890.
Zabeti, N.; Bonin, P.; Volkman, J. K.; Guasco, S.; Rontani, J.-F. Fatty acid composition of bacteria associated with living cells of Emiliania huxleyi. Lipids, unpublished (submitted).
Dur, L. A. D. Isolation and characterization of branched chain fatty acids (other than those derived from phytol) in cod liver oil. Int. J. Food Sci. Technol. 1983, DOI: 10.1111/j.1365-2621.1983.tb00261.
Carballeira, N. M.; Maldonado, M. E. 7-Methyl-8-hexadecenoic acid: a novel fatty acid from the marine sponge Desmapsama anchorata. Lipids. 1988, 23, 690–693.
Imbs, A. B.; Rodkina, S. A. Isolation of 2-methyl branched unsaturated very long fatty acids from marine sponge Halichondria panacea and identification of them by GC-MS and NMR. Chem. Phys. Lipids. 2004, 129, 173–181.
Couderc, F. Gas chromatography/tandem mass spectrometry as an analytical tool for the identification of fatty acids. Lipids. 1995, 30, 691–699.
Suutari, M.; Laasko, S. Signature GLC-MS ions in identification of Δ5- and Δ9-unsaturated iso- and anteiso-branched fatty acids. J. Microbiol. Methods. 1993, 17, 39–48.
Wilkes, H.; Rabus, R.; Fisher, T.; Armstroff, A.; Behrends, A.; Widdel, F. Anaerobic degradation of n-hexane in a denitrifying bacterium: Further degradation of the initial intermediate (1-methylpentyl)succinate via C-skeleton rearrangement. Arch. Microbiol. 2002, 177, 235–243.
Rontani, J.-F. Electron ionization mass spectrometric determination of double bond position in monounsaturated α,β- and β,γ-isomeric isoprenoid acids. Rapid Commun. Mass Spectrom. 1998, 12, 961–967.
Christie, W. W. The lipid library. http://www.lipidlibrary.co.uk/ms/masspec.html.
Boon, J. J.; de Graaf, B.; Schuyl, P. J. W.; de Lange, F.; de Leeuw, J. W. The mass spectrometry of iso- and anteiso-monoenoic fatty acids. Lipids. 1977, 12, 717–721.
McLafferty, F. W.; Turecek, F. Interpretation of mass spectra, 4th ed.; University Science Books: Sausalito, CA, 1993; p. 231.
Kingston, D. G.; Bursey, J. T.; Bursey, M. M. Intramolecular hydrogen transfer in mass spectra. II. The McLafferty rearrangement and related reactions. Chem. Rev. 1974, 74, 215–242.
Yagüe, G.; Segovia, M.; Valero-Guillèn, P. L. Phospholipid composition of several clinically relevant Corynebacterium species as determined by mass spectrometry: an unusual fatty acyl moiety is present in inositol-containing phospholipids of Corynebacterium urealyticum. Microbiol. 2003, 149, 1675–1685.
Rontani, J.-F.; Aubert, C. Electron ionization mass spectral fragmentation of C19 isoprenoid aldehydes and carboxylic acid methyl and trimethylsilyl esters. Rapid Commun. Mass Spectrom. 2003, 17, 949–956.
Zaknun, J.; Elmaleh, D. R.; Guan, J.-G.; Fischman, A. J. Effect of monounsaturation of a branched acid on organ selectivity. J. Nuclear Med. 1995, 36, 2062–2068.
Author information
Authors and Affiliations
Corresponding author
Additional information
Published online August 12, 2009
Rights and permissions
About this article
Cite this article
Rontani, JF., Zabeti, N. & Aubert, C. Double bond migration to methylidene positions during electron ionization mass spectrometry of branched monounsaturated fatty acid derivatives. J Am Soc Mass Spectrom 20, 1997–2005 (2009). https://doi.org/10.1016/j.jasms.2009.07.020
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1016/j.jasms.2009.07.020