Partial separation of polyunsaturated fatty acid esters from FAMEs mixtures by adsorption on silver nitrate-impregnated silica gel

Mixtures of FAMEs derived from soybean and canola oils were fractionated by contacting their hexane solutions with AgNO₃/SiO₂ adsorbents. Methyl linolenate (18∶3) adsorbed most strongly, followed by methyl linoleate (18∶2), on the AgNO₃/SiO₂. Conditions of the extractions (AgNO₃ loading, amount of adsorbent, methyl soyate/hexane solution concentration, use of successive extractions, and methods of adsorbent regeneration) were varied. Under optimal conditions, the 7.0% of 18∶3 in methyl soyate could be reduced to 0.1%. The described process is a simple method for separating a FAMEs mixture into a fraction that is depleted in polyunsaturated FAMEs and one that is enriched.