Proton nuclear magnetic resonance rapid and structure‐specific determination of<i>ω</i>‐3 polyunsaturated fatty acids in fish lipids

Sacchi, Raffaele; Medina, Isabel; Aubourg, Santiago P.; Addeo, Francesco; Paolillo, Livio

doi:10.1007/bf02545299

Cited by 90 publications

(74 citation statements)

References 14 publications

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“…1), a consequence of their closer proximity to the nearest carbon-carbon double bond and, as noted previously by our laboratory (36) and others (24,25), the ratio of the intensities of these two clearly resolved signals (i.e., 0.940:0.846 ppm) yields the n-3:n-6 fatty acid ratio for fish oil supplements. Moreover, expression of the 0.940 ppm resonance intensity to that corresponding to the sum of both the terminal-CH 3 group signals provides a useful index regarding the ratio of total n-3 to non-n-3 fatty acids, and hence the molar percentage of the former present in the samples examined.…”

Section: D 1 H Nmr and 2d 1 H-1 H Nmr Analysis Of Fatty Acid Componesupporting

confidence: 77%

“…Resonances present in the 1 H NMR spectra of marine oil products were assigned by a consideration of chemical shift values, coupling patterns, and coupling constants, with special reference to previously conducted 1 H NMR studies of n-3 fatty acids present in fish oils (24,25,28). The relative intensities of signals were determined by electronic integration, and the concentrations of selected components were computed by comparing their resonance areas with that of the added TCB.…”

Section: Proton 1 H Nmr Measurements and Sample Preparationmentioning

confidence: 99%

“…High-resolution NMR analysis has been previously successfully employed for determinations of the DHA and total n-3 fatty acid contents of fish oils and further fish products (23)(24)(25)(26)(27)(28). However, with the exception of a 13 C NMR study focused on the positional distribution of DHA and EPA between the 1(3)-and 2-glycerol backbone positions of triacylglycerols (29), this technique has not been applied to the multicomponent analysis of encapsulated marine oil supplements fortified with essential vitamin nutrients.…”

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confidence: 99%

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Multicomponent analysis of encapsulated marine oil supplements using high-resolution 1H and 13C NMR techniques

Siddiqui

Sim

Silwood

et al. 2003

Journal of Lipid Research

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Multicomponent high-resolution 1 H and 13 C NMR analysis has been employed for the purpose of detecting and quantifying a wide range of fatty acids (as triacylglycerols or otherwise) in encapsulated marine cod liver oil supplements. The 1 H NMR technique provided quantitative data regarding the docosahexaenoic acid content of these products, which serves as a valuable index of fish oil quality, and a combination of both 1 H and 13 C spectroscopies permitted the analysis of many further components therein, including sn -1 monoacylglycerols, sn -1,2 and -1,3 diacylglycerol adducts, together with a range of minor components, such as trans -fatty acids, free glycerol and cholesterol, and added vitamins A and E. The identities of each of the above agents were confirmed by the application of two-dimensional 1 H-1 H spectroscopies. The NMR techniques employed also uniquely permitted determinations of the content of nonacylglycerol forms of highly unsaturated (or other) fatty acids in these products (i.e., ethyl esters), and therefore served as a means of distinguishing "natural" sources of cod liver oils from those subjected to chemical modification to and/ or supplementation with synthetic derivatives such as ethyl docosahexaenoate or eicosopentaenoate. The analytical significance and putative health effects of the results acquired are discussed.

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Section: D 1 H Nmr and 2d 1 H-1 H Nmr Analysis Of Fatty Acid Componesupporting

confidence: 77%

Section: Proton 1 H Nmr Measurements and Sample Preparationmentioning

confidence: 99%

mentioning

confidence: 99%

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Multicomponent analysis of encapsulated marine oil supplements using high-resolution 1H and 13C NMR techniques

Siddiqui

Sim

Silwood

et al. 2003

Journal of Lipid Research

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“…By integration of distinct 1 H NMR signals, a quantification of unusual fatty acids in lipid mixtures can be effected in an easy and non-destructive way, as was shown for cyclopropene [74], n-3 fatty acids [79], and epoxy [5] fatty acids.…”

Section: H Nuclear Magnetic Resonance Spectroscopymentioning

confidence: 95%

“…Furthermore, it is possible to distinguish fatty acids that contain a double bond at the n-3 terminal [8,79,80] from other unsaturated fatty acid isomers by means of their terminal methyl signals. In the case of an Euphorbiaceae seed oil, that contained two n-3 acids (linolenic and α-parinaric acid (18:4(9c, 11t, 13t, 15c)), even the separation of their terminal methyl and allylic methylene 1 H NMR signals ( Fig.…”

Section: H Nuclear Magnetic Resonance Spectroscopymentioning

confidence: 99%

Screening analysis of unknown seed oils

Spitzer¹

1999

Fett/Lipid

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In the present paper, modern tools for the screening analysis of unknown seed oils have been reviewed. The known plant fatty acid structures have been divided into three groups (usual, unusual nonoxygenated, unusual oxygenated fatty acids) and examples for each class are presented. Moreover, the importance of chemotaxonomy for the screening analysis of some lipid components is discussed. The main part of the work is focussed on various aspects of preliminary seed oil analyses for the detection of unusual fatty acids and lipid classes and the analysis of fatty acid derivatives by gas chromatography and gas chromatography/mass spectrometry. Furthermore, some useful methods to obtain rapid information on the configuration of double bonds are cited. The paper concludes with a scheme for the detection of unusual fatty acids and lipid classes in seed oils.

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Lipid Analyses in Food

Marini¹

2000

Encyclopedia of Analytical Chemistry

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The term lipid encompasses a great host of compounds (e.g. fatty acids (FAs), mono‐, di‐ and triglycerides), that are almost ubiquitously present in foods; their characterization and quantification is then of importance for an analytical chemist. The first step for an accurate analysis is sample preparation: choosing an appropriate solvent or phases can isolate one particular class of lipid from a sample [a good separation of classes can be accomplised by thin‐layer chromatography (TLC)]; obviously, the sample pretreatment will be governed by the determinations to follow. Indeed, nowadays, there is a host of techniques, mainly chromatographic, for lipid analysis. TLC is a rapid way to gather information about the sample (presence of conjugated double and triple bonds, free FAs and of oxygenated FAs), particularly with the development of modified normal phases. For example, silica gel can be impregnated with boric acid, which inhibits isomerization of mono‐ and diglycerides, or it can be treated with silver ions [argentation, for silver ion thin‐layer chromatography (Ag‐TLC)] used for resolution of unsaturated FAs. Gas chromatography (GC) and high‐performance liquid chromatography (HPLC) are the most common techniques actually employed, because of their versatility (many parameters can be changed, e.g. stationary and mobile phases, detector) and to their capacity to be hyphenated (coupled with another measuring device). Particularly, the advent of the light‐scattering detector has allowed greater reproducibility in the HPLC of lipids. Mass spectrometry (MS) is often coupled with GC. However, coupling MS with another MS (MS/MS or tandem MS) is useful for the determination of the structure of long‐chain FAs with improved selectivity and sensitivity. Finally, nuclear magnetic resonance (NMR) is able to identify functional groups, even in mixtures, and is a valid aid for the elucidation of structures with double bonds (DBs) by interpretation of the coupling patterns. Each analytical method relies on appropriate sample preparation (e.g. methylation for the GC analysis of FAs) and a critical approach to evaluate its usefulness.

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Proton nuclear magnetic resonance rapid and structure‐specific determination ofω‐3 polyunsaturated fatty acids in fish lipids

Cited by 90 publications

References 14 publications

Multicomponent analysis of encapsulated marine oil supplements using high-resolution 1H and 13C NMR techniques

Multicomponent analysis of encapsulated marine oil supplements using high-resolution 1H and 13C NMR techniques

Screening analysis of unknown seed oils

Lipid Analyses in Food

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