Volatolomics is the name given to all experiments and analyses of volatile organic compounds (VOCs) emitted by different biological matrices (saliva, urine, blood, exhaled breath). Nowadays, in the context of predictive medicine, the analysis of VOCs contained in exhaled breath is of particular interest to clinicians. Their collection is easy and non-invasive and hundreds of them constitute potential markers of pathologies or of the response to drug treatments.
Proton Transfer Mass Spectrometry (PTR-TOF-MS[1]) is a promising technology for the real-time analysis of VOCs. Initially developed for environmental analysis of single samples, its application to exhaled breath analysis requires new algorithms and software tools. Thus, a correct distinction of the signals between the exhaled breath and ambient air phases is necessary, as well as a modeling of the variation during the acquisition time, to optimize the quantification of the compounds. Moreover, the analysis of clinical cohorts in real time requires signal alignment functionalities between samples and computational performances thanks to parallel processing.
A user-friendly tool…
In this perspective, the ptairMS software has been developed through a collaboration between the metabolomics data science team (SPI/Department of Drugs and Technologies for Health) of the Joliot Institute, the CEA LIST and the Exhalomics® platform of the University of Versailles Saint-Quentin and the Foch Hospital. It is available in open source on the Bioconductor software platform.
… and reliable!
In their study published in Bioinformatics, the researchers present results concerning the detection of VOCs, both on simulated data and on experimental data. With a detection sensitivity and specificity of 99% and 98.4% respectively, ptairMS shows very good discrimination of exhaled breath compounds. The software has already been successfully used to study VOCs from the exhaled breath of intubated, mechanically ventilated patients with COVID-19 and has enabled to discover a biomarker signature for severe forms of the disease (Metabolomics of exhaled breath in critically ill COVID-19 patients: A pilot study, eBioMedicine 2021, January volume 63).
By facilitating the analysis of VOCs in exhaled breath, the new functionalities of the ptairMS software show once again that the research carried out at the CEA can meet the needs of health care institutions.
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[1] PTR-TOF-MS : Proton-Transfer-Reaction coupled to Time-Of-Flight Mass-Spectrometry.