Determination of <i>trans</i> double bonds in polyunsaturated fatty acid methyl esters from their electron impact mass spectra

Mjøs, Svein A.; Pettersen, Jan

doi:10.1002/ejlt.200390031

Cited by 42 publications

(57 citation statements)

References 40 publications

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“…Similar approaches have been used for the determination of double bond positions in monounsaturated acetates [10,11] and long-chain alcohols [10]. Another example is the identification of trans geometry in the unsaturated fatty acids [12,13]. A further advantage of the statistical approach is that the reliability of the identification can be calculated from the error estimates of the regression or classification.…”

Section: Generalmentioning

confidence: 99%

“…Details are described elsewhere [13]. Fractions were collected every 2 min and the following gradient program was applied: Solvent A: hexane, Solv.…”

Section: Silver Ion Chromatography (Ag-lc)mentioning

confidence: 99%

“…It has been shown that trans geometry in specific positions in MI polyenes has significant influence on the mass spectra [13]. The MLR models are therefore expected to fail if applied on certain trans isomers.…”

Section: Selection Of Ions For Simmentioning

confidence: 99%

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The prediction of fatty acid structure from selected ions in electron impact mass spectra of fatty acid methyl esters

Mjøs¹

2004

Euro J Lipid Sci & Tech

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The prediction of fatty acid structure from selected ions in electron impact mass spectra of fatty acid methyl estersThe possibility of fatty acid identification from ions in the mass region of 50-110 amu in electron impact mass spectra has been studied by application of various multivariate techniques. The focus has mainly been on the prediction of the number of double bonds in methylene-interrupted polyunsaturated fatty acids isolated from marine lipids.The number of double bonds in these fatty acids could be predicted with high accuracy, both by partial least squares regression on all ions in this region, and by multiple linear regressions on selected subsets of 5-6 ions. The subsets with optimal predictive power have been found, and the ability to distinguish between methylene interrupted polyunsaturated fatty acids and other fatty acids have also been evaluated.

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Section: Generalmentioning

confidence: 99%

“…Details are described elsewhere [13]. Fractions were collected every 2 min and the following gradient program was applied: Solvent A: hexane, Solv.…”

Section: Silver Ion Chromatography (Ag-lc)mentioning

confidence: 99%

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The prediction of fatty acid structure from selected ions in electron impact mass spectra of fatty acid methyl esters

Mjøs¹

2004

Euro J Lipid Sci & Tech

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“…As a standard procedure, fatty acids are derivatized to methyl esters that are less polar and more volatile, therefore suitable for analysis by GC [8]. MS of fatty acid methyl esters (FAMEs), on the other hand, are believed to provide little structural information such as the position and geometry of double bonds [9]. Pyrrolidide, picolinyl, and dimethyl oxazoline derivatives [10], double-bond deuteration, silylation [11], and preparation of dimethyl disulfide adducts [12] are among the derivatization methods used for the determination of double-bond positions.…”

mentioning

confidence: 99%

“…Pyrrolidide, picolinyl, and dimethyl oxazoline derivatives [10], double-bond deuteration, silylation [11], and preparation of dimethyl disulfide adducts [12] are among the derivatization methods used for the determination of double-bond positions. While many studies have been made on the determination of the position of double bonds, there are very few reports on identification of the geometry of double bonds in fatty acids using mass spectrometry [9,[13][14][15][16][17][18][19][20][21]. These methods include fast atom bombardment (FAB) [13,19], collision induced MS of fatty acids cationized by copper [14], acetonitrile chemical ionization [15], resonance electron capture [16], electron impact ionization (EI) of picolinyl derivatives and chemometrics [17], EI of 2-alkenyl-4,4-dimethyl-oxazolin derivatives [18], and EI of Diels-Alder adducts using 5,5-dimethoxy-1,2,3,4-tetrachlorocyclopentadiene [20,21].…”

mentioning

confidence: 99%

Discrimination among geometrical isomers of α-linolenic acid methyl ester using low energy electron ionization mass spectrometry

Hejazi

Ebrahimi

Guilhaus

et al. 2009

J. Am. Soc. Mass Spectrom.

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There is a consensus that electron impact ionization mass spectrometry is not capable of discriminating among geometrical isomers of unsaturated fatty acid methyl esters (and in general olefinic compounds). In this paper, we report the identification of all eight geometrical isomers of ␣-linolenic acid, one of the few essential -3 fatty acids that has attracted great attention, using low-energy electron ionization mass spectrometry. Three electron energies 70, 50, and 30 eV were studied and the mass spectrum of each isomer was obtained from the analysis of different concentrations of a standard mixture of ␣-linolenic acid methyl ester geometrical isomers to ensure the robustness of the method. Principal component analysis was employed to model the complex variation of m/z intensities across the isomers. Only using the data of 30 eV energy was complete differentiation among geometrical isomers observed. The unique cleavage pattern of the ␣-linolenic acid methyl ester isomers leading to a benzenium ion structure is discussed and general fragmentation rules are derived using the mass spectra of over 300 compounds with different kinds and levels of unsaturation. Application of the proposed method is not limited to ␣-linolenic acid. It can potentially be used to identify the geometrical isomers of any compounds with an olefinic chain. (J Am Soc Mass Spectrom 2009, 20, 1272-1280

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Quantification of linolenic acid isomers by gas chromatography‐mass spectrometry and deconvolution of overlapping chromatographic peaks

Mjøs¹

2004

Euro J Lipid Sci & Tech

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Quantification of linolenic acid isomers by gas chromatography-mass spectrometry and deconvolution of overlapping chromatographic peaksThe use of a technique for deconvolution of overlapping chromatographic peaks, Gentle, has been evaluated for quantification of alpha linolenic acid isomers analysed by gas chromatography-mass spectrometry. Mixtures containing varying amounts of linolenic acid methyl ester isomers with two or three trans double bonds were analysed by two different temperature programs. Overlapping chromatographic peaks were resolved by Gentle, and the areas of the resolved peaks were compared with reference values calculated by use of internal standards. The results show that the small differences that exist between the mass spectra of the analysed isomers are sufficient to achieve deconvolution of severely overlapping peaks. The errors were larger than seen for quantification of chromatographically resolved peaks. Especially for small peaks in a peak cluster, the errors relative to the peak size were large.

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Determination of trans double bonds in polyunsaturated fatty acid methyl esters from their electron impact mass spectra

Cited by 42 publications

References 40 publications

The prediction of fatty acid structure from selected ions in electron impact mass spectra of fatty acid methyl esters

The prediction of fatty acid structure from selected ions in electron impact mass spectra of fatty acid methyl esters

Discrimination among geometrical isomers of α-linolenic acid methyl ester using low energy electron ionization mass spectrometry

Quantification of linolenic acid isomers by gas chromatography‐mass spectrometry and deconvolution of overlapping chromatographic peaks

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