Low temperature direct methylation of lipids in biological materials.

The procedure for low temperature methylation of fatty acids in lipids by sulfuric acid-methanol has been adapted to direct methylation of fatty acids of lipids in biological materials without prior extraction of the lipids. Successful application requires a solution or a suspension of fine particles of the lipid bearing material in ether. Concentrated sulfuric acid is added to the solution or suspension at low temperatures followed by addition of absolute methanol. The acid is neutralized by methanolic KOH and the esters extracted. Application of the method to prepare methyl esters of lipids in cream, blood serum, swine liver and kidney tissue, and cells of yeast onStaphylococcus aureus show that fatty acid composition based on this method compares with that determined by methylation of extracted lipids.