Application of temperature to lipid analysis by silver-ion HPLC: Limitations of the methodology

ANYL 12

Richard O. Adlof, adlofro@ncaur.usda.gov and Gary R. List, listgr@ncaur.usda.gov. Food and Industrial Oil Research, National Center for Agricultural Utilization Research - ARS/USDA, 1815 N. University Street, Peoria, IL 61604
Silver-ion HPLC (Ag-HPLC), utilizing columns packed with silver ions bonded to a silica or similar substrate and isocratic solvent systems of acetonitrile in hexane, has proven to be a tremendously powerful technique for the analysis geometric and/ or positional fatty acid (FA) esters and triacylglycerol (TAG) isomers. While temperature control and programing have become important and integral parts of gas chromatography, the technology has, until recently, found only limited application(s) in HPLC. Solvent temperature rather than composition could be adjusted to improve elution times and sample resolution but, unlike GC, samples eluted more rapidly at lower temperatures. Column temperatures of -40C to +70C were utilized and the effect of temperature on sample resolution, elution times and elution orders studied. The impact/mechanism of temperature vs. sample retention (sample, solvent and substrate interactions), as well as advantages, limitations, and potential future applications of the methodology will be discussed.