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Analytical and Bioanalytical Chemistry

, Volume 410, Issue 22, pp 5507–5519 | Cite as

Pesticide analysis by pulsed flow modulation GCxGC-MS with Cold EI—an alternative to GC-MS-MS

  • Uri Keshet
  • Paulina Goldshlag
  • Aviv Amirav
Research Paper
Part of the following topical collections:
  1. Food Safety Analysis

Abstract

We explored the use of pulsed flow modulation (PFM) two-dimensional comprehensive gas chromatography (GCxGC) mass spectrometry with supersonic molecular beams (SMB) (also named Cold electron ionization (EI)) for achieving universal pesticide analysis in agricultural products. The use of GCxGC serves as an alternative to MS-MS in the needed reduction of matrix interference while enabling full-scan MS operation for universal pesticide analysis with reduced number of false negatives. Matrix interference is further reduced with Cold EI in view of the enhancement of the molecular ions. Pulsed flow modulation is a simple GCxGC modulator that does not consume cryogenic gases while providing tuneable second GCxGC column injection time for enabling the use of quadrupole-based mass spectrometry regardless its limited scanning speed. PFM-GCxGC-MS with Cold EI combines improved separation of GCxGC with Cold EI benefits of tailing-free ultra-fast ion source response time and enhanced molecular ions for the provision of increased sample identification information and reduced matrix interference. Consequently, PFM GCxGC-MS with Cold EI also improved NIST library identification probabilities of the spiked pesticides. PFM GCxGC is further characterized by largely increased second column sample and matrix capacity that as a result performs much better than thermal modulation GCxGC-MS with standard EI in the suppression of matrix interference. In a comparison with standard GC-MS, we measured with PFM GCxGC-MS with Cold EI an average total ion count matrix interference reduction factor of 32 for 12 pesticides in two matrices of baby leaves mixture and lettuce. In addition, Cold EI further increases the range of pesticides amenable for GC-MS analysis and its response is relatively uniform hence with it the need for pesticides specific calibration is reduced.

Graphical abstract

Pulsed flow modulation GCxGC-MS with Cold EI significantly reduces matrix interference and improves sample identification.

Keywords

Pulsed flow modulation GCxGC GCxGC-MS Supersonic molecular beams Cold EI Pesticide analysis 

Notes

Funding

This research was supported by the Israel Science Foundation founded by the Israel Academy of Sciences and Humanities (grant No 356/15). This research was also supported by the Ministry of Science and Technology, Israel, and by the Pazi grant number 266/15 of the Israel Atomic Energy Commission.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  1. 1.School of ChemistryTel Aviv UniversityTel AvivIsrael
  2. 2.Israel Plant Protection and Inspection ServicesBeit DaganIsrael

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