PTR‐ToF‐MS for breath analysis on animal and humans as a noninvasive tool to monitor diseases and diet interactions

The coupling of a Time of Flight mass spectrometer with PTR-MS greatly improved the analytical capability of PTR-MS technology thanks to the higher mass range and higher mass and time resolution. Conversely the larger and more complex data generated requires great efforts to handle and extract the analytical information. We recently developed a full methodology from basic mass spectra handling to the application of up-to date data mining methods which allows for extracting highly relevant features from large amounts of complex spectral data. In the present contribution we show our recent experience in breath analysis using a PTR-ToF-MS instrument. In a first study, we implemented a procedure to measure exhaled breath in awake rats commonly used as model study for different diseases. In particular we monitored the influence of the diet on the physiology state of rats affected by non-alcoholic steatohepatitis (NASH) showing the possibility to discriminate the animals both according to diet regime and the presence of steatohepatitis. A second study was conducted on humans affected by different liver pathologies. Data analysis is complete for the case of cirrhosis: different volatile compounds (2-pentanone, C8-ketone, 2 monoterpenes and 4 sulphur compounds) discriminate healthy subjects from patients affected by cirrhosis at different severity stages and in some cases it was possibile to identify significant correlations between their breath concentration and serum bilirubin. According to our experience, PTR-ToF-MS resulted to be a valid instrument for breath analysis allowing the simultaneous screening and monitoring of hundreds of compounds. Moreover, analytical information entangled in the recorded spectra and extracted with ad hoc procedure brought to the identification of compounds related to liver disease and to the physiological state of subject as influenced by the diet. We believe that the new PTR-MS configuration will boost the research in the field of breath analysis providing a tool for the real time and non-invasive diagnosis and, because of the possibility to measure many subjects