Author
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Adlof, Richard |
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Submitted to: World Congress International Society for Fat Research
Publication Type: Abstract Only Publication Acceptance Date: 9/20/2001 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Silver ion high performance liquid chromatography (Ag-HPLC) has proven itself to be a very versatile procedure for the separation/ characterization of cis and trans geometric and positional fatty acid esters and, to a lesser extent, triacylglycerol (TAG) isomer mixtures containing fatty acids of differing geometries, chain lengths and/or positions on the glycerol backbone. We applied Ag-HPLC [Varian ChromSpher Lipids (c); dual-column; acetonitrile (ACN) in hexane as solvent; UV detection] to the analysis of structured lipids [TAGs with SUS and SSU configuration, where S = stearic acid (S) and U = unsaturated [oleic (O), linoleic (L), or linolenic (Ln)] fatty acids] synthesized by our group. We found Ag-HPLC a suitable, more rapid alternative to enzyme- or gas chromatography-based techniques for structure determination. The analysis of underivatized diacylglycerol mixtures by Ag-HPLC was also possible at room temperature (ca. 21 C), although a stronger solvent (higher % ACN) was required to elute and separate the 1,2- and 1,3-DAGs. (This effect is probably due to normal phase contributions of unreacted silanols on the silica-based substrate of the Lipids column.) A good correlation (% composition of each isomer; analysis by Ag-HPLC) was noted between the 1,2- and 1,3 DAG ratios before esterification and the resultant SSU and SUS TAG ratios. Monoacylglycerols (MAGs) could not be analyzed by this method due to their limited solubility in the ACN/hexane solvent system. The use of more polar solvents such as methanol or isopropanol resulted in gradual loss of column efficiency. |
