Mass spectrometric localization of methyl branching in fatty acids using acylpyrrolidines

Localization of a methyl branch in a fatty acid molecule by mass spectrometry is facilitated by using the pyrrolidide rather than the methyl ester. Branched fatty acid methyl esters are converted to pyrrolidides and are than analyzed by gas chromatography and mass spectrometry. The diagnostic fragments indicate position of the methyl branch.