We report a study of the generation of negatively charged sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) reverse micelles (RMs) in the gas phase, using electrospray ionization guided-ion-beam tandem mass spectrometry.  It was found that singly and doubly charged aggregates dominate in the mass spectra, with the compositions of [(NaAOT)nAOTZ]Z- (n = 1-18 and Z = 1-2).  Encapsulation of hydrophilic glycine, hydrophobic tryptophan as well as deprotonated tryptophan into RMs was achieved, respectively.  Gas-phase NaAOT RMs of aggregation number n = 8 could encapsulate one glycine molecule, and those of n = 12 can encapsulate two glycine molecules.  RMs could accommodate hydrophobic tryptophan from the size of n = 4;  but deprotonated tryptophan can be encapsulated only in singly charged RMs. Collision-induced dissociation of both empty and amino acids-encapsulating reverse micellar ions with Xenon was performed to probe their structures and determine preferential incorporation sites of various amino acids.

Formation, structures, and encapsulation properties of multiply charged, negative NaAOT reverse micelles in the gas phase

244th National Meeting (2012)

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