FAST-ATOM BOMBARDMENT-INDUCED CONDENSATION OF GLYCEROL WITH AMMONIUM SURFACTANTS .2. TIME-DEPENDENCE OF MASS-SPECTRA AND TANDEM MASS-SPECTRA

Studies of fast-atom bombardment (FAB)-induced condensation between tr imethyltetradecylammonium cations and glycerol have been extended to c onsider spectral time dependence. To enhance reproducibility of time d ependence, a modified FAB target was used. FAB mass spectrometry of de uterium-labeled surfactants and FAB/collision-induced dissociation (CI D) of nonlabeled material demonstrate that products of condensation at the surfactant ''head group'' predominate early in the analysis, whil e tail adducts become prominent later. This time dependence correlates with the expected surface activity of the products. It is incompatibl e with gas-phase reaction, but consistent with reaction in the condens ed phase. Subtle variations in the surface activities of various conde nsation products (derived from changes in the number of hydroxyls from the reactive glycerol radical or in the position of attack along the surfactant chain) are reflected in the time dependence of FAB and CID spectra. CID spectra of deuterium-labeled cations provide evidence for intramolecular hydrogen transfer from the surfactant tail to the head within a surfactant radical. This transfer shows no significant kinet ic isotope effect.