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B. Kirchsteiger, M. Kistler, F. Klauser, H. Stressler, R. Sturmlechner, A. Kasper-Giebl:
"Analysis of highly loaded emission samples using a thermal-optical method- advantages of a manual evaluation method";
Poster: 12th International Conference on Carbonaceous Particles in the Atmosphere, Palais Eschenbach, Eschenbachgasse 11, 1010 Vienna, AUSTRIA; 03.04.2019 - 06.04.2019; in: "12th International Conference on Carbonaceous Particles in the Atmosphere", (2019), S. 86.

Carbonaceous compounds represent a major fraction of particulate matter. This holds true for ambient air samples, but is even more obvious when emission samples from residential wood combustion are evaluated. Still, a comprehensive chemical analysis of emission samples is necessary to determine emission factors, or to obtain source profiles which can later be used for source apportionment. Despite considerable adjustments quantification of highly loaded emission samples is still associated with considerable challenges, i.e. inhomogeneous contribution on filters or high filter loadings, which demand the analysis of small sample aliquots and may set additional limits to optical methods.

This study represents a manual quantification method for highly loaded emission samples from different firewood combustion devices. Sampling was divided into hot and cooled total suspended particle (TSP) samples. Sampling of hot flue gas was realized downstream the combustion chamber, while `cooled-phase samples´ were sampled after dilution with compressed air. Analysis of organic carbon (OC) and elemental carbon (EC) was performed in duplicates by an OCEC analyzer (Sunset Laboratory Inc.), applying the EUSAAR_2 protocol in the transmission mode. Generally different contributions of the carbonaceous aerosol fractions could be observed in the hot and cooled-phase samples. Hot-phase samples consist primarily of EC while OC was primarily quantified in cooled-phase samples. First the split point between OC and EC was conducted automatically. Using this method the uncertainty of EC concentrations was rather high, when the duplicate samples were compared. This effect, that was obviously driven by the small changes of the laser signal during the first part of the analysis, made a manual verification of the split-point necessary.
The calculation of the manual split-point is based on the calculation of the highest laser signal before it significantly decreases during the inert phase (He-phase) of quantification. Different to the automatic method, no defined time interval at the beginning of the analyses was set to determine the highest value of the laser signal. This manual evaluation reduces the methods uncertainty of EC measurement, which was based on replicate analysis of emission samples, significantly. Thus, filter loadings ranging up to 2059 µg cm-2 of OC and 2571 µg cm-2 for EC could be evaluated.

thermal-optical method, emission, carbonaceous compounds