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Title: Is electrospray emission really due to columbic forces?

Electrospray ionization (ESI) is a widely adopted soft ionization method for mass spectroscopy (MS). In spite of the undeniable success of the technique, its mechanisms are difficult to be analytically modelled because the process is characterized by non-equilibrium conditions. The common belief is that the formation of gas-phase ions takes place at the apex of the Taylor cone via electrophoretic charging. The charge balance implies that a conversion of electrons to ions should occur at the metal-liquid interface of the injector needle. We have detected that the above description is based on unproved assumptions which are not consistent with the correct evaluation of the problem. The comparison between experiments performed under the usual geometry and observations obtained under symmetric field configurations suggests that the emitted droplets cannot be significantly charged or, at least, that any possible ionization mechanism is so poorly efficient to ensure that columbic forces cannot play a major role in jet formation, even in cases where the liquid consists of a solution of ionic species. Further work is required to clearly understand how ionization occurs in ESI-MS.
Authors:
; ; ;  [1] ;  [2] ;  [3]
  1. CNR-Istituto per i Processi Chimico-Fisici, Viale F. Stagno d’Alcontres 37, I-98158 Messina (Italy)
  2. CNR-Istituto per lo Studio dei Materiali Nanostrutturati, via dei Taurini 19, I-00185 Roma (Italy)
  3. Adam Mickiewicz University, Faculty of Physics, Umultowska 85, PL-62614 Poznan (Poland)
Publication Date:
OSTI Identifier:
22299765
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 4; Journal Issue: 9; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; DROPLETS; EMISSION; IONIZATION; LIQUIDS; MASS SPECTROSCOPY