Isotopic specific NO concentration measurements in human breath and plant emission

Metrology in Life Sciences

The detection of nitric oxide (NO) is of considerable medical interest. NO is involved in a multitude of mammal physiological processes and various non-invasive concentration determination methods for NO have been developed during the last years. Regarding time resolved metabolism behavior the quantitative determination of the 15N16O-isotopologue in combination with 15N-labeled drugs and amino acids is a central interest of current medical research. We apply laser-induced fluorescence (LIF) spectroscopy for isotope-selective detection of NO in various biological environments with a theoretical detection limit below 0.1 parts per trillion (ppt). Electronic excitation of the A(v'=0) <- X(v”=0) transition in the UV provides fluorescence around 247nm from A(v'=0) -> X(v''=2). For an online measurement of human exhaled air, a respiratory mask has been constructed and integrated into our system. Main advantages of this device compared to established methods are the high sensitivity for NO concentrations in the ppt region, the high time resolution of 20ms and the isotopic selectivity to distinguish between 14NO and 15NO. Visualizations of single exhalation-profiles, long-time online measurements including the determination of absolute NO concentrations as well as the influence of quenching gases present during the experiment are of current interest and subject to further investigations. Especially detection of 15NO online profiles of exhaled human air is part of the research work. These NO investigations will be extended to isotopic specific NO plant emission to further resolve the NO cycle.

TU Braunschweig
Ph.D. student: