Comparison of six methylation methods on marine lipids

5 páginasSix methods widely used to produce methyl esters for the gas chromatographic determination of the fatty acid composition of a marine lipid were compared. Four acid-catalyzed methods (1% H2SO4: CH3OH; 5% HCl: CH3OH; 7% and 14% BF3: CH3OH) and two base-catalyzed methods [0.5M NaOCH3: CH3OH; (1:4) tetramethylguanidine: CH3OH] were used. The use of BF3: CH3OH (7% and 14%) gave a lower content of 18:1 n9 than the other methods and produced an artefact (2.7–3.2% of total fatty acid content) eluting between the 20:5 and 24:1 fatty acid methyl esters. No significant differences were obtained between the other four methods. Accordingly the use of BF3: CH3OH for transmethylation of marine lipids is not recommended. Results obtained in the other four methods showed that all are comparable.Peer reviewe