Go to contents (site navigation)

 


Realised by ALMS™
developer of the AIDS-HIV Reference project
Abstract No.: ThP-008
Session: Atmospheric Pressure Ionization
Presentation date: Thu, Aug 31, 2006
Presentation time: 14:30 – 16:00

Analytical Approach to Ion Transport in "Nozzle – Skimmer" Interface Chamber

Alina Danzheyevna Andreyeva1, Andrei Aleksandrovich Elistratov2

1 Institute for Analytical Instrumentation, Russian Academy of Science, Saint-Petersburg, Russian Federation
2 Institute for Cryptosystems, Communications and Informatics, Moscow, Russian Federation

Correspondence address: Alina Danzheyevna Andreyeva, Institute for Analytical Instrumentation, Russian Academy of Science, Mass Spectrometry, Rizhskii prospekt, 26 lab 233, Saint-Petersburg, 190103 Russian Federation.

Keywords: Calculations, Trajectory; Ion Loss; Ion Mobility; Ion Transport.

Novel aspect: A simple analytical model of ion transport in the interface of traditional type.

 

There is still a need for improvements in interfacial systems of the mass – spectrometers with atmospheric pressure ionization sources. The interface region is characterized by complicated gaseous and electrodynamical conditions that strongly influence the total ion transmission and ion beam characteristics at the entrance of the mass–spectrometer. This complicated nature goes from abruptly changing pressure from atmospheric to a near-vacuum along the interface.

In our work we present a simple analytical model for the estimation of ion beam characteristics at the exit of the interface region. The traditional "nozzle – skimmer" system is investigated by ion transport modeling using continuum-based approximation in a limit of low ion currents. Some models of ion mobility and fragmentation are considered.

The model quickly builds smoothed ion trajectories in a supersonic gas jet and electrical field of the interface. Dependence of the ion current on the nozzle – skimmer voltage is investigated. The model demonstrates the way the ion properties and gaseous and electrodynamical conditions influence the transmission, characteristics of the ion beam in phase space and ion current composition on the exit of the interface.

Our model was approved by numerical simulations of ion trajectories in rarefied gas approximation. It was also experimentally tested with a few samples of inorganic salts. It can be used for estimations and a more clear understanding of the processes engaged in interface, at least the traditional one. It is helpful in our work on isotope and elemental analysis by ESI-MS method.
A simple and methodologically clear analytical model of ion beam formation in traditional "nozzle – skimmer" interfacial system is proposed.