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| Titel |
On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion–isotope ratio mass spectrometry |
| VerfasserIn |
J. Schmitt, B. Seth, M. Bock, C. Veen, L. Möller, C. J. Sapart, M. Prokopiou, T. Sowers, T. Röckmann, H. Fischer |
| 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 ; 6, no. 5 ; Nr. 6, no. 5 (2013-05-27), S.1425-1445 |
| Datensatznummer |
250017903
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| Publikation (Nr.) |
 copernicus.org/amt-6-1425-2013.pdf |
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| Zusammenfassung |
| Stable carbon isotope analysis of methane (δ13C of CH4) on
atmospheric samples is one key method to constrain the current and past
atmospheric CH4 budget. A frequently applied measurement technique is
gas chromatography (GC) isotope ratio mass spectrometry (IRMS) coupled to a
combustion-preconcentration unit. This report shows that the atmospheric
trace gas krypton (Kr) can severely interfere during the mass spectrometric
measurement, leading to significant biases in δ13C of CH4,
if krypton is not sufficiently separated during the analysis. According to
our experiments, the krypton interference is likely composed of two
individual effects, with the lateral tailing of the doubly charged 86Kr
peak affecting the neighbouring m/z 44 and partially the m/z 45 Faraday cups.
Additionally, a broad signal affecting m/z 45 and especially m/z 46 is assumed to
result from scattered ions of singly charged krypton. The introduced bias in
the measured isotope ratios is dependent on the chromatographic separation,
the krypton-to-CH4 mixing ratio in the sample, the focusing of the mass
spectrometer as well as the detector configuration and can amount to up to
several per mil in δ13C. Apart from technical solutions to avoid
this interference, we present correction routines to a posteriori remove the
bias. |
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