Comparison of Methods for the Preparation of Fatty Acid Methyl Esters for the Analysis of Omega‐3 Rich Oils by Gas Chromatography

ABSTRACT Fatty acid analysis is required in a wide range of industries, and conversion to fatty acid methyl esters followed by gas chromatography is by far the most common method of analysis. However, despite widespread use, there is no consensus on which derivatization method should be used or how the methods compare. In this work, five methods for the preparation of fatty acid methyl esters were compared for the analysis of three omega‐3 rich oils (marine, krill, and flaxseed oils). Overall, we found that all methods gave similar results for percentage composition of fatty acids, but some variation existed when comparing absolute quantitation of fatty acids. We also found that the derivatization efficacy of each method varied depending on lipid class, with catalyst type having a significant effect. Two methods employing: (i) methanolic hydrogen chloride and (ii) methanolic sodium hydroxide followed by a boron trihalide reagent (BCl 3 or BF 3 ) had derivatizing efficacies (by lipid class) that were significantly higher than for the other methods.