Darmstadt 2008 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 20: Laseranwendungen (Lebenswissenschaften und Umwelt)

Q 20.2: Talk

Tuesday, March 11, 2008, 14:15–14:30, 3H

Laser-spectroscopic online analysis of hydrocarbons in exhaled human breath — •Sven Thelen, Daniel Halmer, Peter Hering, and Manfred Mürtz — Heinrich-Heine-Universität Düsseldorf, Institut für Lasermedizin, 40225 Düsseldorf, www.ilm.uni-duesseldorf.de/tracegas

The quantitative and single breath-resolved analysis of trace gases contained in human breath has constantly gained importance for medical diagnostics. A prominent example is the ethane molecule which is released as a by-product of free radical induced lipid peroxidation in the human body. Thus a rapid and non-invasive detection of ethane as a volatile marker for the oxidative stress status is very attractive for medical diagnostics.

We use Cavity Leak-Out Spectroscopy (CALOS) implementing a 50 cm long absorption cell enclosed with two high reflectivity mirrors resulting in an effective absorption path length of 3.6 km. Our Difference-Frequency Generation (DFG) laser source provides a continuous tuning range between 3.30 µm and 3.67 µm and a laser power of 280 µW.

With this technique we have analyzed the washout dynamics of ethane in the human body. We have also investigated single breath exhalations of methane regarding reproducibilty of concentration and slope of the alveolar phase. Furthermore we present the results of an intercomparison study with Gas Chromatography/Flame Ionization (GC-FID).