A ToF-MS with a Highly Efficient Electrostatic Ion Guide for Characterization of Ionic Liquid Electrospray Sources

  • Subha ChakrabortyEmail author
  • Caglar Ataman
  • Daniel G. Courtney
  • Simon Dandavino
  • Herbert Shea
Research Article


We report on the development of a time-of-flight (ToF) mass spectrometer with a highly efficient electrostatic ion guide for enhancing detectability in ToF mass spectrometry. This 65-cm long ion guide consists of 13 cascaded stages of Einzel lens to collect a large fraction of emitted charges over a wide emission angle and energy spread for time-of-flight measurements. Simulations show that the ion guide can collect 100% of the charges with up to 23° emission half-angle or 30% energy spread irrespective of their specific charge. We demonstrate this ion guide as applied to electrospray ion sources. Experiments performed with tungsten needle electrospraying the ionic liquid EMI-BF4 showed that up to 80% of the emitted charges could be collected at the end of the flight tube. Flight times of monomers and dimers emitted from the needles were measured in both positive and negative emission polarities. The setup was also used to characterize the electrospray from microfabricated silicon capillary emitters and nearly 30% charges could be collected even from a 40° emission half-angle. This setup can thus increase the fraction of charge collection for ToF measurement and spray characteristics can be obtained from a very large fraction of the emission in real time.

Key words

Mass spectrometry Electrostatic lens Ion guide 



The authors acknowledge Dr. C. N. Ryan from Queen Mary University, London, for important discussions. This work was partially supported by the Swiss National Science Foundation under grant 200021_146365, the ESA NPI programme, and the FP7 MicroThrust project, grant agreement number 263035, funded by the EC Seventh Framework Programme theme FP7-SPACE-2010.

Supplementary material

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Supplementary Figure S1 (DOC 106 kb)
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Supplementary Figure S2 (DOC 106 kb)
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Supplementary Figure S3 (DOC 334 kb)
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Supplementary Figure S4 (DOC 96 kb)


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Copyright information

© American Society for Mass Spectrometry 2014

Authors and Affiliations

  • Subha Chakraborty
    • 1
    Email author
  • Caglar Ataman
    • 1
  • Daniel G. Courtney
    • 1
  • Simon Dandavino
    • 1
  • Herbert Shea
    • 1
  1. 1.Microsystems for Space Technologies LaboratoryEPFLNeuchatelSwitzerland

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