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Synthesis, isolation, and GC analysis of all the 6,8-to 13,15-cis/trans conjugated linoleic acid isomers

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Lipids

Abstract

Octadecadienoic acids with conjugated double bonds are often referred to as conjugated linoleic acid, or CLA. CLA is of considerable interest because of potentially beneficial effects reported from animal studies. Analysis of CLA is usually carried out by GC elution of FAME. If the presence of low-level isomers is of interest, a complementary technique such as silverion HPLC is also used. These analyses have been hindered by a lack of well-characterized commercially available reference materials. Described here are the synthesis and isolation of selected 6,8-through 13,15-positional CLA isomers, followed by isomerization of these CLA isomers with iodine to produce all the possible cis,cis,cis,trans,trans,cis, and trans,trans combinations. Also present are the GC retention times of the CLA FAME relative to γ-linolenic acid (6c,9c,12c-octadecatrienoic acid) FAME using a 100-m CP Sil-88 capillary column (Varian Inc., Lake Forest, CA). These data include all the CLA isomers that have been identified thus far in foods and dietary supplements and should greatly aid in the future analysis of CLA in these products.

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Abbreviations

CLA:

conjugated linoleic acid

ALA:

α-linolenic acid

DMOX:

4,4′-dimethyl-2-oxazoline

GLA:

γ-linolenic acid

MeCN:

acetonitrile

RRT:

relative retention time

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Authors and Affiliations

  1. U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5100 Paint Branch Parkway, HFS-840, Room IE009, 20740, College Park, MD

    P. Delmonte, J. A. G. Roach, M. M. Mossoba & M. P. Yurawecz

  2. Dipartimento di Protezione e Valorizzazione Agro-Alimentare (DIPROVAL), University of Bologna, Bologna, Italy

    G. Losi

Authors
  1. P. Delmonte
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  2. J. A. G. Roach
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  3. M. M. Mossoba
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  4. G. Losi
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  5. M. P. Yurawecz
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Correspondence to M. P. Yurawecz.

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Delmonte, P., Roach, J.A.G., Mossoba, M.M. et al. Synthesis, isolation, and GC analysis of all the 6,8-to 13,15-cis/trans conjugated linoleic acid isomers. Lipids 39, 185–191 (2004). https://doi.org/10.1007/s11745-004-1218-2

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  • DOI: https://doi.org/10.1007/s11745-004-1218-2

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