ABSTRACT
Gas Chromatography-Mass Spectrometry (GC-MS) has been an invaluable tool for determining the positions of double bonds in conjugated linoleic acid (CLA) metabolites formed by elongation/desaturation reactions. GC-MS in identifying a range of CLA metabolites formed in vivo, in detecting artifacts and in differentiating CLA from non-CLA components that run in the same region of the chromatogram, is then considered. Optimum gas chromatographic conditions on long polar columns have been used for maximum separation of positional and geometrical isomers, but it has not been possible to resolve all isomers. An account of the mass spectral properties of suitable derivatives is the usefulness of GC-MS for confirming the identities of CLA isomers in a range of materials. Several peaks that are not CLA isomers may occur in the CLA region of the gas chromatogram of natural CLA samples, and in samples extracted from tissue derived from animals fed commercial CLA.
