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| Titel |
Evaluation of a two-step thermal method for separating organic and elemental carbon for radiocarbon analysis |
| VerfasserIn |
U. Dusek, M. Monaco, M. Prokopiou, F. Gongriep, R. Hitzenberger, H. A. J. Meijer, T. Röckmann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 7 ; Nr. 7, no. 7 (2014-07-03), S.1943-1955 |
| Datensatznummer |
250115835
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| Publikation (Nr.) |
 copernicus.org/amt-7-1943-2014.pdf |
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| Zusammenfassung |
| We thoroughly characterized a system for thermal separation of organic carbon
(OC) and elemental carbon (EC) for subsequent radiocarbon analysis. Different
organic compounds as well as ambient aerosol filter samples were introduced
into an oven system and combusted to CO2 in pure O2. The main
objective was to test which combustion times and temperatures are best suited
to separate OC and EC. The final separation step for OC was combustion at
360 °C for 15 min. Combustion at this temperature proved enough to
remove several organic test substances from the filter (including high
molecular weight humic acid) but did not remove substantial amounts of EC.
For isolation of EC, OC first needs to be completely removed from the filter.
This was achieved by water extraction of the filter, followed by combustion
of the water insoluble OC at 360 °C and combustion at an intermediate
temperature step of 2 min at 450 °C. This last step removed the most
refractory OC together with some EC. Finally, the remaining EC was combusted
to CO2 at 650 °C. The recovery of black carbon after the
intermediate 450 °C step was approximately 80%. Several tests
provided strong evidence that OC was removed efficiently during the
intermediate temperature step: (i) brown carbon, indicative of refractory OC,
was removed; (ii) the fraction modern of EC did not decrease significantly if
the temperature of the intermediate step was further increased. Based on
tests with various organic compounds, we estimated that charred organic
carbon could contribute 4–8% to an elemental carbon sample that was
isolated according to our method. |
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