Retention behavior of trans isomers of eicosapentaenoic and docosahexaenoic acid methyl esters on a polyethylene glycol stationary phase

A polyethylene glycol (PEG) stationary phase was evaluated for the separation of mono-trans isomers of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) methyl esters. The resolution patterns were compared to patterns achieved with previously applied conditions on a cyanopropyl phase. There were no overlaps between all-cis EPA/DHA and their mono-trans isomers on the PEG phase. Because of overlap between 22:0 and 22:1 isomers, the PEG column is not a good choice for analyses of EPA trans isomers in crude fish oils. However, if the saturated and monounsaturated fatty acids are not present in significant amounts, PEG can be a better choice than cyanopropyl columns.