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This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the photoacoustic systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm -1 Hz -0.5 and 4.9E-9 Wcm -1 Hz -0.5 . Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices. • First reported photoacoustic isoprene detection system of real human breath • laser-based photoacoustic setups for human breath analysis of acetone and isoprene. • Reliable calibration and validation of the system against real-time mass spectrometry (PTR-ToF-MS). • 3σ detection limits in the lower ppbV range at 5 s integration time. • Measurements of real breath samples collected under different physiological conditions.
Pangerl et al. (Wed,) studied this question.