title: Electrospray ion mobility mass spectrometry of positively charged sodium bis[2-ethythexyl)sulfosuccinate aggregates.
abstract: Collision cross-sections (CCS) of positively singly and multiply charged aggregates of the surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) in the gas phase have been measured by quadrupole ion mobility time-of-flight mass spectrometry. Calibration of the observed drift times to the CCS of the AOTNa non-covalent aggregates was achieved by collecting, under the same experimental conditions, the drift times of a range of singly and multiply charged polyalanine peptides whose CCS had been obtained by conventional ion mobility spectrometry. Together with an obvious increase of the aggregate cross-section with the aggregation number, it was found that the aggregate cross-section increases with the charge state due to the sodium counterions steric effect and the augmented electrostatic repulsion. This finding is consistent with the result of a previous molecular dynamics study on positively charged AOTNa aggregates in the gas phase showing that, by increasing the charge state, the aggregates become progressively more oblate; implying a rise of their CCS. Moreover, the occurrence at each aggregation number and extra charge of a unique value of cross section points toward aggregates whose conformations do not show discernible shape change in the experiment time scale.
authors.forename: David
authors.initials: D
authors.lastname: Bongiorno
authors.forename: Serena
authors.initials: S
authors.lastname: Indelicato
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giorgi
authors.forename: Simona
authors.initials: S
authors.lastname: Scarpella
authors.forename: Vincenzo Turco
authors.initials: VT
authors.lastname: Liveri
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Ceraulo
mesh_terms: D003198:Computer Simulation; D004143:Dioctyl Sulfosuccinic Acid / Q000032:analysis* / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D055672:Static Electricity
chemical_list: D004143:Dioctyl Sulfosuccinic Acid