Pyrrolidides for mass spectrometric determination of the position of the double bond in monounsaturated fatty acids

Abstract

Abstract Mass spectra of pyrrolidides of monounsaturated straight chain fatty acids are presented and discussed. The spectra of pyrrolidides contain mainly ions from the polar part of the molecule. This gives simple spectra from which double bond positions can be deduced directly. If an interval of 12 atomic mass units is observed between the most intense peaks of clusters of fragments containing n and n−1 carbon atoms of the acid moiety, the double bond occurs between carbons n and n+1 in the molecule This rule is valid for double bonds occurring at positions Δ 5 ‐Δ 15 in an 18‐carbon chain and has been applied to acids having 10–24 carbon atoms.