Silver-ion high-performance liquid chromatographic separation and identification of conjugated linoleic acid isomers.
This is the first report of the application of silver-ion impregnated high-performance liquid chromatography (Ag(+)-HPLC) to the separation of complex mixtures of conjugated linolenic acid (CLA) isomers present in commercial CLA sources and foods and in biological specimens. This method showed a clear separation of CLA isomers into three groups related to their trans,trans, cis,trans or trans,cis, and cic,cis configuration of the conjugated double-bond system. In addition, this method separated individual positional isomers of the conjugated diene system within each geometrical isomeric group. Following Ag(+)-HPLC isolation, gas chromatography (GC)-electron impact mass spectrometry, and GC-direct deposition-Fourier transformed infrared spectroscopy were used to confirm the identity of two major positional isomers in the cis/trans region, i.e., delta 8,10- and delta 11,13-octadecadienoic acids, which had not been chromatographically resolved previously. Furthermore, the potential of this method was demonstrated by showing different Ag(+)-HPLC profiles exhibiting patterns of isomeric distributions for biological specimens from animals fed a diet containing a commercial CLA preparation, as well as for a commercial cheese product.
Sehat
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Food and Drug Administration, Center for Food Safety and Applied Nutrition, Washington, DC 20204, USA.
Yurawecz
M P
MP
Roach
J A
JA
Mossoba
M M
MM
Kramer
J K
JK
Ku
Y
Y
D002414:Cations, Monovalent; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D007536:Isomerism; D008041:Linoleic Acids / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry; D012834:Silver
D002414:Cations, Monovalent; D008041:Linoleic Acids; D010080:Oxazoles; C057549:4,4-dimethyloxazoline; D012834:Silver