Structural determination of unsaturated mycolic acids by fast atom bombardment and tandem mass spectrometry analyses of their amino-alcohol derivatives

Tandem mass spectrometry for collisional activation of alkali metal-cationized fatty acids: a method for determining double bond location

“…However, highly unsaturated fatty acid anions decompose giving little or no structural information (4,13). Moreover, other approaches using MS/CA/MS require prior derivatization of the acid to the ester (14-18) and, in some cases, an additional derivatization of the double bond (17,18). Therefore, it remains advantageous to develop a method whereby free fatty acids can be investigated by using an entirely instrumental approach.…”

Derivatization in Mass Spectrometry—8. Soft Ionization Mass Spectrometry of Small Molecules

“…It should be noted that a similar derivatization approach was used earlier for the structure elucidation of mycolic acids by FAB in conjunction with MS/MS. 160 Chemical transformation of the acids involved three stages: epoxidation, treatment with (CH 3 ) 2 NH and methylation of the carboxyl group. In the FAB mass spectra of such derivatives, abundant molecular protonated ions as well as "amine" fragments are present allowing the determination of a double bond position:…”