Berlin 2012 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 9: Poster session

UP 9.16: Poster

Mittwoch, 28. März 2012, 18:30–19:15, Poster F

Towards traceability in concentration measurements using tunable diode laser based absorption spectroscopy — Javis Nwaboh, •Andrea Pogány, Pascal Ortwein, Olav Werhahn, and Volker Ebert — Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany

We have applied the TILSAM method, to achieve traceability in measuring concentration of trace gases by tunable diode laser absorption spectroscopy. The method promotes traceability and uncertainty assessment of spectrometric results, thereby improves reliability of the measured concentration data. Furthermore, it is an absolute, self-calibrating method, and thereby has the potential to become a primary method in gas analysis. Applying the TILSAM method eliminates the need for calibrating the instrument with high quality reference gas mixtures, preparation of which in the environmentally relevant concentration range is highly challenging.

We have validated the method through an inter-comparison measurement between two national metrology institutes. Both institutes measured CO2 concentration, in two gravimetrically prepared gas mixtures of CO2 in N2 in the environmentally relevant concentration range of 300-500 ppm, using the TILSAM method. Good agreement was found between results derived by the two institutes and the respective comparison reference values (degree of equivalence in the 1% range). The standard uncertainty and the repeatability of the spectrometric results were found to be 0.7% and 0.4%, respectively. The TILSAM method will be applied to environment related metrology projects.