Chromatographic separation and identification of conjugated linoleic acid isomers

There are 56 possible geometric and positional isomers of conjugated octadecadienoic acids (18:2), better known as conjugated linoleic acid (CLA). Positive health benefits are ascribed to the consumption of the 9c,11t-18:2 and 10t, 12c-18:2 isomers. The dietary significance of the other isomers is not known. Our understanding of the biological role of these acids relies on their proper identification and quantitation in complex biological extracts. Gas chromatography (GC) alone cannot completely separate the naturally occurring CLA isomers. The combination of silver ion high performance liquid chromatography (Ag+ HPLC) and GC offers the best separation of these isomers with complementary identification by GC-mass spectrometry (GC-MS) and GC-Fourier transform infrared (FTIR) analyses. (C) 2002 Elsevier Science B.V. All rights reserved.