Double bond localization in unsaturated fatty acid methyl esters (FAME) by solvent mediated chemical ionization (SMCI) tandem mass spectrometry

Characterization of unsaturated fatty acid structures is an unusually difficult chemical problem because of the similarity of the isomeric structures. Enabled by the Shimadzu solvent mediated chemical ionization unit, we implemented covalent adduct chemical ionization. After a straightforward setup procedure, CACI-MS/MS yields unique diagnostic ions that enable structural characterization of most fatty acid methyl esters (FAME) with no need for standard solutions.