ABSTRACT
This chapter discusses various aspects of the analysis of conjugated linoleic acid (CLA) in great depth. Capillary gas chromatography (GC) provides the basis for most analytical approaches to the problem, with GC-mass spectrometry (MS) as an invaluable adjunct. Silver-ion chromatography can be a useful technique for isolation of a fraction enriched in CLA, but it can also afford unrivaled analytical separations. With natural samples, the concentration of CLA isomers by reversed-phase high-performance liquid chromatography and silver-ion chromatography must be considered before analysis by GC or GC-MS. Although GC linked to Fourier transform infrared spectroscopy can provide a great deal of invaluable information, the availability of the technique is limited. Nuclear magnetic resonance (NMR) spectroscopy can also be very useful for commercial CLA samples. With the exception of the NMR spectroscopy, none of the methods so far described gives information on which of the double bonds in a CLA isomer or metabolite is of the cis configuration and which trans.
