The supramolecular charged aggregates formed during ESI ionization of AOTNa
solutions under critical micelle concentration have been studied thorough ion mobility
experiments. In particular, positively charged clusters with several charge states,
ranging from +1 to +4, have been investigated. It has been found that, despite to
previous investigations (Siuzdak et al. 1995, Nohara et al. 1998), specific ionic
aggregates with a peculiar cross section are observed. Indeed a single drift time is
observed for each charged aggregate.
Using both calculated cross section and experimental calibration curves the
experimental cross section of the observed cation has been determined. It is worth
noting that simulated reversed micelle structure (through mobcal EHSS algorithm) cross
section and experimental ones air in fair agreement. This agreement is a further support
that reverse micelle is the most likely structure that characterize such aggregates