Fast Multiplexing of Analytical Parameters for Performance Improvements in Time-of-flight Mass Spectrometry

Oral Presentation

Prepared by D. Wevill1, L. McGregor2, N. Bukowski2, M. Santoro2, J. Blanch2, D. Wevill3, P. Grosshans4
1 - Markes, 2355 Gold Meadow Way, Gold River, CA, 95670, United States
2 - Markes International, Gwaun Elai Mediscience Campus, Llantrisant, RCT, CF728XL, United Kingdom
3 - Markes International, 2355 Gold Meadow Way, Suite 130, Gold River, CA, 95670, United States
4 - Markes, 11126 Kenwood Road, Suite D, Cincinnati, OH, 45242, United States

Contact Information:; 866-483-5684


Time-of-flight mass spectrometry (TOF MS) has made considerable advances in recent years, with the elimination of mass discrimination (crucial for GC couplings), increased sensitivity, and compact instrument designs making the technique more amenable. We will explore a number of advances in TOF MS technology which are set to further increase its applicability.

The term ‘multiplexing’ is used to describe the combination of multiple data streams into a single, comprehensive stream. Multiplexing can be applied to mass spectrometry in a number of ways but, for the purpose of this study, we will focus on extending the dynamic range of the detector by interleaving ionisation periods between consecutive scans, as well as fast-switching of electron energies to collect both hard (70 eV) and soft (10-20 eV) electron ionisation spectra within a single run.

Precise temporal gating of the electron beam permits cooling of ions before their delayed extraction into the analyser of the instrument – minimising space-charge effects and improving the resolution in mass obtainable from a highly compact form factor. Multiplexing of ionisation periods between, say, standard (10 µs) and short (100 ns) duration enables both high sensitivity and high sample loading analyses to be recorded simultaneously, extending detector linear dynamic range by up to 2 orders.
Furthermore, the ion source used in this study enables soft electron ionisation to be performed with no inherent loss in sensitivity. Multiplexing between ionisation energies allows conventional 70 eV spectra to be obtained - for routine identification against commercial libraries - as well as simplified soft EI spectra for enhanced confidence in identification of compounds which may exhibit weak molecular ions and/or similar spectra at 70 eV.

These technological advances will be demonstrated using a number of real-world environmental samples.