Tandem mass spectrometry for identifying fatty acid derivatives that undergo charge‐remote fragmentations

A variety of fatty acid functional derivatives were desorbed by fast atom bombardment and collisionally activated. Derivatives having a high proton affinity such as fatty amides, pyrrolidides and picolinyl esters fragment to give decompositions that originate remote from the charge site. In contrast, derivatives having a low proton affinity such as fatty acids and fatty esters fragment to give charge‐initiated decompositions. Therefore, the choice of the fatty acid functional derivative is important in effecting charge‐remote decompositions of the [M + H]⁺ ions. The collisional activation spectra of the [M + H]⁺ ions of fatty alcohols and fatty amines were also compared. Based on this comparison, the internal energy required in order for charge‐remote fragmentations to occur is estimated to be between 1.4 and 2.9 eV. This work is a guide in designing functional derivatives of fatty acids that undergo charge‐remote reactions.