Preparation of Fatty Acid Methyl Esters and Dimethylacetals from Lipids with Boron Fluoride–methanol

Fatty acid methyl esters and dimethylacetals suitable for gas chromatographic analysis were prepared by treatment of lipids with boron fluoride–methanol (140 g BF3 per liter of methanol). This reagent is stable and easy to handle. Reaction conditions were investigated for triglycerides, diglycerides, monoglycerides, free fatty acids, sterol esters, phosphatidyl ethanolamines, phosphatidyl serines, phosphatidyl cholines, monophosphoinositides, monogalactosyl glycerides, phosphatidal cholines (choline plasmalogens), digalactosyl glycerides, and sphingomyelins. The methyl esters and dimethylacetals were readily purified by thin-layer chromatography, and yields were quantitative. There were few undesirable side reactions, and they did not affect the validity of the method. The procedure developed is simple, rapid, and generally applicable to lipids.