Screening for Biomarkers
The classical application of breath analysis is the search for biomarkers. In such studies, the breath spectra of healthy volunteers are compared to subjects/patients with a certain condition. IONICON PTR-TOFMS instruments are particularly well suited, since the complete spectrum is analyzed at once. In combination with our BET breath sampling inlet, it is possible to analyze all detectable breath compounds down to pptv-levels from a single exhalation.
Breath-Markers for Smoking
The most prominent biomarkers typically found in breath are those for the smoking status of the test subject. These markers should always be identified, since they can easily act as confounding factors for more interesting correlations.
The figure shows a box-plot for the most prominent smoking marker acetonitrile. The data represents over 200 subjects measured. To assess the quality of the resulting breath test, the Area Under the Receiver-Operator-Characteristic curve (AUROC), which, with 99%, represents the best value published so far and shows the potential of the employed method.
Monitoring – A non-invasive window into the body
Real-time breath analysis has also facilitated new types of studies, where the breath of a subject is monitored to follow the variation of one or several marker compounds in time.
Pharmacokinetics is the study of distribution and elimination of drugs in the body. With breath analysis, the blood concentrations of a drug can be monitored non-invasively and can be updated with every exhalation.
In the figure we show full exhalations, recorded every 15 minutes, which depicts the concentration of a drug in the exhaled breath after ingestion (t=0) of a capsule that dissolves in the intestinal tract after a few hours. The concentration shows a sharp increase and a slow decay from which pharmacokinetic models can be derived. An accurate model is not possible with a slower sampling frequency, which makes such studies tedious with offline breath sampling methods and renders it next to impossible with invasive blood analysis (Beauchamp et al.).