Selected Ion Flow Tube Mass Spectrometry SIFT-MS for Real-Time Measurement of Trace Concentrations of Volatile Compounds in Breath and Culture Headspace

Patrik Španěl
J. Heyrovský Institute of Physical Chemistry of CAS, Prague, Czech Republic

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Patrik Španěl (Presenter) J. Heyrovský Institute of Physical Chemistry

Presenter Bio: Patrik Španěl graduated in plasma physics at Charles University, Prague and obtained his PhD at the Innsbruck University, Austria. Currently, he is Head of the Department of Ion and Cluster Chemistry and Chairman of the Board of the J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague. Together with his colleagues he researches into ion chemistry involved in quantification of volatile trace compounds in air, collaborating with life scientists and clinicians in interdisciplinary studies that include exhaled breath analysis and diagnostics of bacterial infections. He is co- author of more than 270 publications that have been cited more than 10000 times (h-index 55).

Relevant Financial Disclosures (within past 24 months) Grant/Research Support European Commission, H2020, Marie Curie ITN Committee/Board/Advisory Board Board of the J. Heyrovský Institute Salary J. Heyrovský Institute Discussing Products? NO, presenter will NOT present educational content related to products/services of the ineligible company(ies) listed above. Conflict mitigation NOT REQUIRED.

INTRODUCTION
The need for rapid and accurate measurement of trace concentrations of compounds present in air and human breath has led to construction of specialised mass spectrometers based on the Selected Ion Flow Tube Mass Spectrometry, SIFT-MS, and its drift tube variant, SIFDT-MS.

OBJECTIVES
The primary objective was to quantify in real time volatile compounds including ammonia, hydrogen sulphide or hydrogen cyanide present in concentrations as low as a part per billion by volume (ppbv) in human breath and in the headspace of bacterial cultures. The specific objective was to reduce the size of the instrumentation whilst improving sensitivity.

METHODS
The selected reagent ions (either H3O+, NO+ or O2+) for selective chemical ionization of volatile compounds present in the air matrix are created in an external ion source and injected into the the flow or flow-drift tube reactors with well-defined reaction time. The absolute concentrations of the analytes can thus be accurately quantified using the chemical kinetics principles.

RESULTS
Concentrations of volatile metabolites present in breath were determined by SIFT-MS in several case studies focused at ammonia, acetone, hydrogen cyanide, methanol, pentane and acetic acid. In vitro studies of the VOCs emitted by bacteria illustrate the search for exhaled breath biomarkers of airways infections.

CONCLUSION
SIFT-MS is now recognized as a valuable method for the analysis of air and breath allowing real time analysis on time scale of seconds, minutes or hours. SIFDT-MS has a potential for construction of much smaller instruments for accurate analyses in matrices such as exhaled breath and bacterial culture headspace.