Identification and Characterization of Conjugated Fatty Acid Methyl Esters of Mixed Double Bond Geometry by Acetonitrile Chemical Ionization Tandem Mass Spectrometry

Michaud, Anthony L.; Yurawecz, M. P.; Delmonte, Pierluigi; Corl, Benjamin A.; Bauman, Dale E.; Brenna, J. Thomas

doi:10.1021/ac034221+

Cited by 68 publications

(80 citation statements)

References 19 publications

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“…2B ). The lower relative intensity of the m/z 264 ion for RLnA, compared with RA and the unknown C18:3 peak, results from the cis confi guration at carbon number 15 ( 5 ). For the unknown C18:3 peak, the lower intensity of the m/z 318 ion, compared with RLnA, and the relative elution order of the unknown C18:3 peak indicate a trans double-bond confi guration located at carbon number 15.…”

Section: Methodsmentioning

confidence: 98%

Characterization of cis-9 trans-11 trans-15 C18:3 in milk fat by GC and covalent adduct chemical ionization tandem MS

Gómez‐Cortés

Tyburczy

Brenna

et al. 2009

Journal of Lipid Research

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This article is available online at http://www.jlr.org the biohydrogenation of ␣ -linolenic acid ( cis -9 cis -12 cis -15 C18:3) in ruminants involves an initial isomerization to a conjugated triene ( cis -9 trans -11 cis -15 C18:3) named rumelenic acid (RLnA) followed by hydrogenation of double bonds at carbons 9, 15, and 11 to yield trans -11 cis -15 C18:2, trans -11 C18:1 (vaccenic acid), and C18:0 ( 1 ). Structural characterization of RLnA was recently confi rmed by GC-MS after synthesis of both its picolinyl ester and dimethyloxazoline (DMOX) derivative ( 2 ), and different studies confi rmed that minute amounts of ␣ -linolenic acid biohydrogenation intermediates are present in milk fat ( 3, 4 ). However, molecular structure of other minor intermediates also produced from dietary PUFA biohydrogenation and after transferred to milk fat still remains unclear.Although analysis of picolinyl esters or DMOX derivatives by electron impact GC-MS have demonstrated to be useful for identifying double bond positions in PUFA, this approach does not supply a reliable assignment of geometrical confi guration. In contrast, covalent adduct chemical ionization tandem mass spectrometry (CACI-MS/MS) serves as a powerful tool for identifying positional and geometric isomers of conjugated linoleic acid (CLA) methyl esters ( 5 ) and should prove quite useful for the analysis of conjugated diene methyl esters with longer chain length as well ( 6, 7 ). CACI-MS/MS concentrates signal in a very few diagnostic ions, which can then be plotted as indicators for the parent compound. Furthermore, this technique allowed the direct analysis of fatty acid methyl esters Abbreviations: Ag + -HPLC, silver ion high performance liquid chromatography; CLA, conjugated linoleic acid; CACI-MS, covalent adduct chemical ionization mass spectrometry; CACI-MS/MS, covalent adduct chemical ionization tandem mass spectrometry; DMOX dimethyloxazoline; FAME, fatty acid methyl esters; FID, fl ame ionization detector; RA, rumenic acid, cis -9 trans -11 C18:2; RLnA, rumelenic acid, cis -9 trans -11 cis -15 C18:3; TMR, total mixed ration; t R , retention time.

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Section: Methodsmentioning

confidence: 98%

Characterization of cis-9 trans-11 trans-15 C18:3 in milk fat by GC and covalent adduct chemical ionization tandem MS

Gómez‐Cortés

Tyburczy

Brenna

et al. 2009

Journal of Lipid Research

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“…Intriguingly, Brenna and co-workers found distinctive behavior for FAMEs bearing conjugated dienes, noting that the appearance of diagnostic -and -product ions strongly depended on the geometry (i.e., cis and trans) of the double bonds [29].…”

Section: Introductionmentioning

confidence: 99%

“…Subsequent collision-induced dissociation (CID) of these adducts gives diagnostic and predictable product ions that can be used to localize double bond position(s). This approach has been combined with chromatography to effect the separation and identification of polyunsaturated FAMEs derived from a range of isomeric linoleic and linolenic acids [29].…”

Section: Introductionmentioning

confidence: 99%

Ozone-Induced Dissociation of Conjugated Lipids Reveals Significant Reaction Rate Enhancements and Characteristic Odd-Electron Product Ions

Maccarone

Campbell²,

Mitchell

et al. 2013

J. Am. Soc. Mass Spectrom.

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. Ozone-induced dissociation of conjugated lipids reveals significant reaction rate enhancements and characteristic odd-electron product ions. Journal of the American Society for Mass Spectrometry, 24 (2), 286-296.Ozone-induced dissociation of conjugated lipids reveals significant reaction rate enhancements and characteristic odd-electron product ions AbstractOzone-induced dissociation (OzID) is an alternative ion activation method that relies on the gas phase ionmolecule reaction between a mass-selected target ion and ozone in an ion trap mass spectrometer. Herein, we evaluated the performance of OzID for both the structural elucidation and selective detection of conjugated carbon-carbon double bond motifs within lipids. The relative reactivity trends for [M + X]+ ions (where X = Li, Na, K) formed via electrospray ionization (ESI) of conjugated versus nonconjugated fatty acid methyl esters (FAMEs) were examined using two different OzID-enabled linear ion-trap mass spectrometers. Compared with nonconjugated analogues, FAMEs derived from conjugated linoleic acids were found to react up to 200 times faster and to yield characteristic radical cations. The significantly enhanced reactivity of conjugated isomers means that OzID product ions can be observed without invoking a reaction delay in the experimental sequence (i.e., trapping of ions in the presence of ozone is not required). This possibility has been exploited to undertake neutral-loss scans on a triple quadrupole mass spectrometer targeting characteristic OzID transitions. Such analyses reveal the presence of conjugated double bonds in lipids extracted from selected foodstuffs. Finally, by benchmarking of the absolute ozone concentration inside the ion trap, second order rate constants for the gas phase reactions between unsaturated organic ions and ozone were obtained. These results demonstrate a significant influence of the adducting metal on reaction rate constants in the fashion Li > Na > K. second order rate constants for the gas phase reactions between unsaturated organic ions and ozone were obtained. These results demonstrate a significant influence of the adducting metal on reaction rate constants in the fashion Li > Na > K.3

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“…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].…”

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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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Identification and Characterization of Conjugated Fatty Acid Methyl Esters of Mixed Double Bond Geometry by Acetonitrile Chemical Ionization Tandem Mass Spectrometry

Cited by 68 publications

References 19 publications

Characterization of cis-9 trans-11 trans-15 C18:3 in milk fat by GC and covalent adduct chemical ionization tandem MS

Characterization of cis-9 trans-11 trans-15 C18:3 in milk fat by GC and covalent adduct chemical ionization tandem MS

Ozone-Induced Dissociation of Conjugated Lipids Reveals Significant Reaction Rate Enhancements and Characteristic Odd-Electron Product Ions

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

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