Analysis of Cationic Surfactants by Mass Spectrometry/Mass Spectrometry with Fast Atom Bombardment

The utility of tandem mass spectrometry (MS/MS) combined with fast atom bombardment Ionization (FAB) for surveying and characterizing catlonlc surfactants Is demonstrated for the first time. The surfactant types successfully studied Include amines, amine salts, quaternary amines, amine oxides, polyethoxylated quaternary amines, and amphoteric compounds. Homologue distributions and molecular weight Information were obtained from positive ion FAB spectra. Parent Ions generated by FAB were mass selected and then caused to undergo collision-activated dissociation (CAO). The resulting fragment ion (CAD) spectra contained the structural Information as to surfactant type, length anil number of alky) chains, presence of Isomers, and degree of ethoxylation. Negative ion FAB spectra were used to Identify the anionic counterion and the presence of anionic functionalities In amphoteric species. Mixture analysis and structure identification were performed rapidly and without sample preseparation or derivatization.