Trends in Direct Breath Analysis by Secondary Electrospray Ionization Mass Spectrometry for Clinical Applications

Exhaled breath can reveal insights about the metabolic state of the human body through the endo- and exogenous compounds it contains. The extent of detectable compounds, however, was revolutionized by the application of mass spectrometry. More specifically, secondary electrospray ionization high-resolution mass spectrometry (SESI-HRMS) enables the detection of a broad range of breath-derived compounds simultaneously and with high sensitivity. Together with its rapid and non-invasive nature, direct breath analysis by SESI-HRMS raised particular interest for clinical applications. Over the past years, various clinical trials successfully demonstrated the technology´s capability for biomarker discovery in exhaled breath in adults and more recently in children. Current challenges lie within the potential translation of SESI-HRMS into clinical settings and the requirements therein, such as biomarker identification and validation, which became a focus of more recent studies.