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Wu J, Ji Y, Zhao L, Ji M, Ye Z, Li S. A Mass Spectrometric Analysis Method Based on PPCA and SVM for Early Detection of Ovarian Cancer. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:6169249. [PMID: 27642365 PMCID: PMC5011755 DOI: 10.1155/2016/6169249] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/17/2016] [Accepted: 07/13/2016] [Indexed: 11/18/2022]
Abstract
Background. Surfaced-enhanced laser desorption-ionization-time of flight mass spectrometry (SELDI-TOF-MS) technology plays an important role in the early diagnosis of ovarian cancer. However, the raw MS data is highly dimensional and redundant. Therefore, it is necessary to study rapid and accurate detection methods from the massive MS data. Methods. The clinical data set used in the experiments for early cancer detection consisted of 216 SELDI-TOF-MS samples. An MS analysis method based on probabilistic principal components analysis (PPCA) and support vector machine (SVM) was proposed and applied to the ovarian cancer early classification in the data set. Additionally, by the same data set, we also established a traditional PCA-SVM model. Finally we compared the two models in detection accuracy, specificity, and sensitivity. Results. Using independent training and testing experiments 10 times to evaluate the ovarian cancer detection models, the average prediction accuracy, sensitivity, and specificity of the PCA-SVM model were 83.34%, 82.70%, and 83.88%, respectively. In contrast, those of the PPCA-SVM model were 90.80%, 92.98%, and 88.97%, respectively. Conclusions. The PPCA-SVM model had better detection performance. And the model combined with the SELDI-TOF-MS technology had a prospect in early clinical detection and diagnosis of ovarian cancer.
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Affiliation(s)
- Jiang Wu
- College of Electrical Engineering and Instrumentation, Jilin University, Changchun 130061, China
| | - Yanju Ji
- College of Electrical Engineering and Instrumentation, Jilin University, Changchun 130061, China
| | - Ling Zhao
- First Hospital, Jilin University, Changchun 130021, China
| | - Mengying Ji
- College of Electrical Engineering and Instrumentation, Jilin University, Changchun 130061, China
| | - Zhuang Ye
- First Hospital, Jilin University, Changchun 130021, China
| | - Suyi Li
- College of Electrical Engineering and Instrumentation, Jilin University, Changchun 130061, China
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Li S, Xu J, Chen J, Chen J, Zhou C, Yan X. Structural elucidation of co-eluted triglycerides in the marine diatom model organism Thalassiosira pseudonana by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:245-255. [PMID: 24375875 DOI: 10.1002/rcm.6784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 11/02/2013] [Accepted: 11/07/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE The precise identification of fatty acids at the sn-2 position of triacylglycerols (TAGs), especially for positional regioisomers (AAB/ABA), needs to be established during mass spectrometry analysis. The detailed structural information about TAGs is significant not only for the assessment of biofuel quality, but also for the tracing of biosynthetic precursors. METHODS Total lipid was extracted from T. pseudonana by a modified Bligh and Dyer method. The qualitative analysis of TAGs in T. pseudonana was carried out using ultra-performance liquid chromatography/electrospray ionization-quadrupole time-of-flight mass spectrometry (UPLC/ESI-Q-TOF-MS). The raw LC/MS data were analyzed using MassLynx software (version 4.1, Waters). RESULTS The acyl group at the sn-2 position of the TAGs has been identified unequivocally by [M + Li-R1/3COOH-R2CH=CHCOOH](+) and the abundance of [M + Li-R1/3COOH-R2CH=CHCOOH](+) can be used to confirm whether the TAG isomers are co-eluted. In total, twelve TAGs were identified in T. pseudonana based on the fragmentation patterns discussed above. The data indicated that only C16 fatty acids were located at the sn-2 position, which was important to trace the biosynthetic precursors of TAGs. CONCLUSIONS We put forward a hypothesis that TAGs in T. pseudonana are only derived from lipids in chloroplasts through prokaryotic biosynthesis pathway based on the precise information of sn-2 fatty acids, which is significant not only for the assessment of biofuel quality, but also for the tracing of biosynthetic precursors.
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Affiliation(s)
- Shuang Li
- Key Laboratory of Applied Marine Biotechnology, Ningbo University, Chinese Ministry of Education, Ningbo, Zhejiang, 315211, P.R. China; School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, P.R. China
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Bhuiyan M, Tucker D, Watson K. Determination and differentiation of triacylglycerol molecular species in Antarctic and non-Antarctic yeasts by atmospheric pressure-chemical ionization-mass spectrometry. J Microbiol Methods 2013; 94:249-56. [DOI: 10.1016/j.mimet.2013.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 06/08/2013] [Accepted: 06/08/2013] [Indexed: 10/26/2022]
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Wang Y, Zhao M, Ou S, Song K, Han X. Preparation of diacylglycerol-enriched palm olein by phospholipase A1-catalyzed partial hydrolysis. EUR J LIPID SCI TECH 2009. [DOI: 10.1002/ejlt.200800294] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Pittenauer E, Allmaier G. The renaissance of high-energy CID for structural elucidation of complex lipids: MALDI-TOF/RTOF-MS of alkali cationized triacylglycerols. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:1037-47. [PMID: 19251438 DOI: 10.1016/j.jasms.2009.01.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 01/13/2009] [Accepted: 01/16/2009] [Indexed: 05/19/2023]
Abstract
Triacylglycerols were analyzed as cationized species (Li(+), Na(+), K(+)) by high-energy CID at 20 keV collisions utilizing MALDI-TOF/RTOF mass spectrometry. Precursor ions, based on [M + Li](+)-adduct ions exhibited incomplete fragmentation in the high and low m/z region whereas [M + K](+)-adducts did not show useful fragmentation. Only sodiated precursor ions yielded product ion spectra with structurally diagnostic product ions across the whole m/z range. The high m/z region of the CID spectra is dominated by abundant charge-remote fragmentation of the fatty acid substituents. In favorable cases also positions of double bonds or of hydroxy groups of the fatty acid alkyl chains could be determined. A-type product ions represent the end products of these charge-remote fragmentations. B- and C-type product ions yield the fatty acid composition of individual triacylglycerol species based on loss of either one neutral fatty acid or one sodium carboxylate residue, respectively. Product ions allowing fatty acid substituent positional determination were present in the low m/z range enabling identification of either the sn-1/sn-3 substituents (E-, F-, and G-type ions) or the sn-2 substituent (J-type ion). These findings were demonstrated with synthetic triacylglycerols and plant oils such as cocoa butter, olive oil, and castor bean oil. Typical features of 20 keV CID spectra of sodiated triacylglycerols obtained by MALDI-TOF/RTOF MS were an even distribution of product ions over the entire m/z range and a mass accuracy of +/-0.1 to 0.2 u. One limitation of the application of this technique is mainly the insufficient precursor ion gating after MS1 (gating window at 4 u) of species separated by 2 u.
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Affiliation(s)
- Ernst Pittenauer
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Austria.
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Wang Y, Zhao M, OU S, Xie L, Tang S. Preparation of a diacylglycerol-enriched soybean oil by phosphalipase A1 catalyzed hydrolysis. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.molcatb.2008.07.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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WANG YONG, ZHAO MOUMING, OU SHIYI, SONG KEKE. PARTIAL HYDROLYSIS OF SOYBEAN OIL BY PHOSPHOLIPASE A1TO PRODUCE DIACYLGLYCEROL-ENRICHED OIL. ACTA ACUST UNITED AC 2009. [DOI: 10.1111/j.1745-4522.2009.01136.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Xu Y, Brenna JT. Atmospheric pressure covalent adduct chemical ionization tandem mass spectrometry for double bond localization in monoene- and diene-containing triacylglycerols. Anal Chem 2007; 79:2525-36. [PMID: 17279727 PMCID: PMC2517902 DOI: 10.1021/ac062055a] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a method to elucidate the structure of triacyl-glycerols (TAGs) containing monoene or diene fatty acyl groups by atmospheric pressure covalent adduct chemical ionization (APCACI) tandem mass spectrometry using acetonitrile as an adduct formation reagent. TAGs were synthesized with the structures ABB and BAB, where A is palmitate (C16:0) and B is an isomeric C18 monoene unsaturated at position 9, 11, or 13 or an isomeric diene unsaturated at positions 9 and 11, 10 and 12, or 9 and 12. In addition to the species at m/z 54 observed in previous CI studies of fatty acid methyl esters, we also found that ions at m/z 42, 81, and 95 undergo covalent reaction with TAGs containing double bonds to yield ions at m/z 40, 54, 81, and 95 units greater than that of the parent TAG: [M + 40]+, [M + 54]+, [M + 81]+, and [M + 95]+ ions. When collisionally dissociated, these ions fragment to produce two or three diagnostic ions that locate the double bonds in the TAG. In addition, ions [RCH=C=O + 40]+ and [RCH=C=O + 54]+ formed from collisional dissociation are of strong abundance in MS/MS spectra, and collisional activation of these ions produces two intense confirmatory diagnostic ions in the MS3 spectra. Fragment ions reflecting neutral loss of an sn-1-acyl group from [M + 40]+ and [M + 54]+ are more abundant than those reflecting neutral loss of an sn-2-acyl group, analogous to previous reports for protonated TAGs. The position of each acyl group on the glycerol backbone is thus determined by the relative abundances of these ions. Under the conditions in our instrument, the [M + 40]+ adduct is at the highest signal and also yields all information about the double bond position and TAG stereochemistry. With the exception of geometries about the double bonds, racemic TAG isomers containing two monoenes or dienes and a saturate can be fully characterized by APCACI-MS/MS/MS.
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Affiliation(s)
| | - J. Thomas Brenna
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
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Gidden J, Liyanage R, Durham B, Lay JO. Reducing fragmentation observed in the matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of triacylglycerols in vegetable oils. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2007; 21:1951-7. [PMID: 17526066 DOI: 10.1002/rcm.3041] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Edible oils consist primarily of triacylglycerols (TAGs). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra of the oils are typically dominated by sodium adducts of these TAGs but also show prominent fragment ions (that do not contain sodium), which can interfere with analytical measurements of other components in oils. The fragments seemingly correspond to the loss of a fatty acid moiety from the sodiated TAGs as a sodium salt: RCOONa. However, a previous study suggested that the fragments actually arise from nearly complete fragmentation of unseen protonated TAGs. These authors suggested that the fragmentation occurs so rapidly and completely that protonated TAGs are not normally observed in the spectra of these oils. In this paper, we present evidence to support their theory and also demonstrate an approach to eliminate these interfering ions from the MALDI-TOF mass spectra via addition of a base to the matrix/sample mixture. The added base does not impede formation of the sodiated TAGs, but does significantly reduce the amount of fragments observed. We propose that this occurs by depleting the H+ ions from the matrix, thus preventing the formation of significant numbers of protonated TAGs in the first place. For measurements by MALDI-TOF, the relative abundances of the fragment ions are related to the strength of the base, and can be almost completely eliminated. However, in longer time-scale experiments such as in post-source decay and Fourier transform mass spectrometry, sodiated and non-sodiated diacylglycerol (DAG)-like fragments are present in spectra, regardless of whether or not a base is added to the sample.
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Affiliation(s)
- Jennifer Gidden
- Arkansas Statewide Mass Spectrometry Facility, University of Arkansas, Fayetteville, AR 72701, USA
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Segall S, Artz W, Raslan D, Ferraz V, Takahashi J. Analysis of triacylglycerol isomers in Malaysian cocoa butter using HPLC–mass spectrometry. Food Res Int 2005. [DOI: 10.1016/j.foodres.2004.09.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Cserháti T. Mass spectrometric detection in chromatography. Trends and perspectives. Biomed Chromatogr 2002; 16:303-10. [PMID: 12210503 DOI: 10.1002/bmc.165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The newest results in the use of miscellaneous mass spectrometric detection methods in various chromatographic techniques are compiled and critically evaluated. Examples of application in clinical chemistry, health care, and in the analysis of pharmaceuticals, environmental pollutants, foods and food products are given. The benefits and drawbacks of MS detection are discussed, and future trends are briefly discussed.
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Affiliation(s)
- Tibor Cserháti
- Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, PO Box 17, 1525 Budapest, Hungary
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Andrikopoulos NK. Triglyceride species compositions of common edible vegetable oils and methods used for their identification and quantification. FOOD REVIEWS INTERNATIONAL 2002. [DOI: 10.1081/fri-120003418] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Han X, Gross RW. Quantitative analysis and molecular species fingerprinting of triacylglyceride molecular species directly from lipid extracts of biological samples by electrospray ionization tandem mass spectrometry. Anal Biochem 2001; 295:88-100. [PMID: 11476549 DOI: 10.1006/abio.2001.5178] [Citation(s) in RCA: 258] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Herein we describe a rapid, simple, and reliable method for the quantitative analysis and molecular species fingerprinting of triacylglycerides (TAG) directly from chloroform extracts of biological samples. Previous attempts at direct TAG quantitation by positive-ion electrospray ionization mass spectrometry (ESI/MS) were confounded by the presence of overlapping peaks from choline glycerophospholipids requiring chromatographic separation of lipid extracts prior to ESI/MS analyses. By exploiting the rapid loss of phosphocholine from choline glycerophospholipids, in conjunction with neutral-loss scanning for individual fatty acids, overlapping peaks in the ESI mass spectrum were deconvoluted generating a detailed molecular species fingerprint of individual TAG molecular species directly from chloroform extracts of biological samples. This method readily detects as little as 0.1 pmol of each TAG molecular species from chloroform extracts and is linear over a 1000-fold dynamic range. The sensitivity of individual TAG molecular species to ESI/MS/MS analyses correlated with the unsaturation index and inversely correlated with total aliphatic chain length of TAG. An algorithm was developed which identifies sensitivity factors, thereby allowing the rapid quantitation and molecular species fingerprinting of TAG molecular species directly from chloroform extracts of biological samples.
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Affiliation(s)
- X Han
- Division of Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Kim YH, So KY, Limb JK, Jhon GJ, Han SY. Identification of triacylglycerols containing two short-chain fatty acids at sn-2 and sn-3 positions from bovine udder by fast atom bombardment tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2000; 14:2230-2237. [PMID: 11114033 DOI: 10.1002/1097-0231(20001215)14:23<2230::aid-rcm156>3.0.co;2-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Several triacylglycerol (TAG) molecular species, that contain two short-chain fatty acids (C4 to C8) at the sn-2 and sn-3 positions of the glycerol backbone, were isolated from bovine udder by using solvent extraction and silica gel column chromatography. Their structures were identified by fast atom bombardment (FAB) tandem mass spectrometry (MS/MS), based on the information obtained from collision-induced dissociation (CID) spectra of sodium-adducted molecules ([M + Na](+)) of model TAG compounds which had been synthesized from glycerol and appropriate fatty acids. For each species, the relative positions of the three fatty acids on the glycerol backbone, as well as fatty acid composition and double-bond position in the fatty acyl group, were determined. A majority of sodium-adducted molecules observed in the FAB mass spectrum were mixtures of at least two components that have different fatty acid composition but the same molecular mass. In addition, all the components present in mixtures of all the species contain a long-chain fatty acid (C12 to C18) at the sn-1 position, a short-chain fatty acid (C4 to C8) at the sn-2 position, and a butyric acid uniquely at the sn-3 position.
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Affiliation(s)
- Y H Kim
- Complex Carbohydrate Research Center, University of Georgia, 220 River Bend Road, Athens, GA 30602-4712, USA.
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Hsu FF, Turk J. Structural characterization of triacylglycerols as lithiated adducts by electrospray ionization mass spectrometry using low-energy collisionally activated dissociation on a triple stage quadrupole instrument. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1999; 10:587-599. [PMID: 10384723 DOI: 10.1016/s1044-0305(99)00035-5] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We describe features of tandem mass spectra of lithiated adducts of triacylglycerol (TAG) species obtained by electrospray ionization mass spectrometry (ms) with low-energy collisionally activated dissociation (CAD) on a triple stage quadrupole instrument. The spectra distinguish isomeric triacylglycerol species and permit assignment of the mass of each fatty acid substituent and positions on the glycerol backbone to which substituents are esterified. Source CAD-MS2 experiments permit assignment of double bond locations in polyunsaturated fatty acid substituents. The ESI/MS/MS spectra contain [M + Li - (RnCO2H)]+, [M + Li - (RnCO2Li)]+, and RnCO+ ions, among others, that permit assignment of the masses of fatty acid substituents. Relative abundances of these ions reflect positions on the glycerol backbone to which substituents are esterified. The tandem spectra also contain ions reflecting combined elimination of two adjacent fatty acid residues, one of which is eliminated as a free fatty acid and the other as an alpha, beta-unsaturated fatty acid. Such combined losses always involve the sn-2 substituent, and this feature provides a robust means to identify that substituent. Fragment ions reflecting combined losses of both sn-1 and sn-3 substituents without loss of the sn-2 substituent are not observed. Schemes are proposed to rationalize formation of major fragment ions in tandem mass spectra of lithiated TAG that are supported by studies with deuterium-labeled TAG and by source CAD-MS2 experiments. These schemes involve initial elimination of a free fatty acid in concert with a hydrogen atom abstracted from the alpha-methylene group of an adjacent fatty acid, followed by formation of a cyclic intermediate that decomposes to yield other characteristic fragment ions. Determination of double bond location in polyunsaturated fatty acid substituents of TAG is achieved by source CAD experiments in which dilithiated adducts of fatty acid substituents are produced in the ion source and subjected to CAD in the collision cell. Product ions are analyzed in the final quadrupole to yield information on double bond location.
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Affiliation(s)
- F F Hsu
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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A chemometric study of genotypic variation in triacylglycerol composition among selected almond cultivars. J AM OIL CHEM SOC 1999. [DOI: 10.1007/s11746-999-0229-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Zissis KD, Brereton RG, Dunkerley S. Principal components scores and loadings plots for visualisation of the electrospray ionisation liquid chromatography mass spectra of a mixture of chlorophyll degradation products at different cone voltages. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 1999; 13:1755-1761. [PMID: 10455245 DOI: 10.1002/(sici)1097-0231(19990915)13:17<1755::aid-rcm710>3.0.co;2-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Positive ion electrospray liquid chromatography mass spectrometry was performed on a mixture of allomers obtained from the degradation of chlorophyll a, at three cone voltages. An approach is described for obtaining principal components loadings and scores plots, involving mass selection, normalisation and standardisation of the data, principal components analysis and three dimensional projections. The loadings plots group ions which are assigned to five major compounds in the mixture by reference to the scores. At higher cone voltage fragmentation and differentiation between compounds with identical molecular weights is observed.
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Affiliation(s)
- K D Zissis
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
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Cheng C, Gross ML, Pittenauer E. Complete structural elucidation of triacylglycerols by tandem sector mass spectrometry. Anal Chem 1998; 70:4417-26. [PMID: 9796425 DOI: 10.1021/ac9805192] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We developed a method to elucidate the complete structure of triacylglycerols by means of high-energy collisional activation tandem mass spectrometry (MS/MS). Both ESI- and FAB-produced [M + NH4]+ and [M + met.]+ ions (where met. = Li, Na, and Cs) of triacylglycerols undergo charge-remote and charge-driven fragmentations. We emphasize the study of fragment ions from ESI-produced [M + NH4]+ and [M + Na]+ ions and FAB-produced [M + Na]+ ions. ESI-produced [M + NH4]+ ions fragment to produce four types of ions, [M + NH4 - RnCOONH4]+, [RnCO + 128]+, [RnCO + 74]+, and RnCO+ ions, from which the carbon number and the degree of unsaturation of each acyl group are obtained. In addition, three series of ions are produced by charge-remote fragmentations (CRFs), and analysis of their patterns gives the position and the number of double bonds on the acyl groups. Information about the position of each acyl group on the glycerol backbone, however, is not provided by collisionally activated dissociation of [M + NH4]+ ions. On the other hand, ESI- and FAB-produced [M + Na]+ ions fragment to form eight types of ions (named A-J ions) that, like those produced by CRF, are highly structurally informative. The absence of certain series members also carries useful structural information. Interpretation of these patterns enables one to obtain the number of carbons, degrees of unsaturation, and location of double bonds, as well as the positions of acyl groups on the glycerol backbone.
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Affiliation(s)
- C Cheng
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA
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Review of cocoa butter and alternative fats for use in chocolate—Part B. Analytical approaches for identification and determination. Food Chem 1998. [DOI: 10.1016/s0308-8146(97)00161-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Affiliation(s)
- Steven D. Brown
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716-2522
| | - Stephen T. Sum
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716-2522
| | - Frederic Despagne
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716-2522
| | - Barry K. Lavine
- Department of Chemistry, Clarkson University, Potsdam, New York 13676
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Laakso P. Analysis of triacylglycerols— approaching the molecular composition of natural mixtures. FOOD REVIEWS INTERNATIONAL 1996. [DOI: 10.1080/87559129609541075] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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