Abstract
CLA, defined as one or more octadecadienoic acids (18∶2) with conjugated double bonds, has been reported to be active in a number of bological systems. GC and silver ion HPLC (Ag+-HPLC) have been the primary techniques for identifying specific CLA isomers in both foods and biological extracts. Recently, GC relative retention times were reported for all c,c, c/t (c,t and t,c), and t,t CLA FAME from the 6,8- to the 13,15-positions in octadecadienoic acid (18∶2). Presented here is the relative retention order of the same CLA FAME using Ag+-HPLC with two different elution systems. The first elution system, consisting of 0.1% acetonitrile/0.5% diethyl ether (DE)/hexane, has been used previously to monitor CLA composition in foods. Also presented here is the retention order of CLA FAME using 2% acetic acid/hexane elution solvent, which has advantages of more stable retention volumes and a complementary elution order of CLA FAME isomers. The data are reported using retention volumes (RV) adjusted for toluene, an estimator for dead volume, and relative to c9,t11-18∶2. Measurement of relative RV in the analysis of 88 samples of cow plasma, milk, and rumen fluids using Ag+-HPLC is also presented here. The % CV ranged from 1.04 to 1.62 for t,t isomers and from 0 to 0.48 for c/t isomers.
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Abbreviations
- DE:
-
diethyl ether
- MeCN:
-
acetonitrile
- RRV:
-
relative retention volume
- RV:
-
retention volume
References
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Delmonte, P., Kataoka, A., Corl, B.A. et al. Relative retention order of all isomers of cis/trans conjugated linoleic acid FAME from the 6,8- to 13,15-positions using silver ion HPLC with two elution systems. Lipids 40, 509–514 (2005). https://doi.org/10.1007/s11745-005-1411-3
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DOI: https://doi.org/10.1007/s11745-005-1411-3