H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer
Cavity ring-down spectrometers (CRDSs) have the capacity to make isotopic measurements of CO<sub>2</sub> where concentrations range from atmospheric (~ 400 ppm) to 6000 ppm. Following field trials, it has come to light that the spectrographic lines used for CO<sub>2</sub> hav...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2015-10-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/8/4075/2015/amt-8-4075-2015.pdf |
| _version_ | 1819263967630983168 |
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| author | K. Malowany J. Stix A. Van Pelt G. Lucic |
| author_facet | K. Malowany J. Stix A. Van Pelt G. Lucic |
| author_sort | K. Malowany |
| collection | DOAJ |
| description | Cavity ring-down spectrometers (CRDSs) have the capacity to make isotopic
measurements of CO<sub>2</sub> where concentrations range from atmospheric
(~ 400 ppm) to 6000 ppm. Following field trials, it has come
to light that the spectrographic lines used for CO<sub>2</sub> have an
interference with elevated (higher than ambient) amounts of hydrogen sulfide
(H<sub>2</sub>S), which causes significant depletions in the δ<sup>13</sup>C
measurement by the CRDSs. In order to deploy this instrument in environments
with elevated H<sub>2</sub>S concentrations (i.e., active volcanoes), we require a
robust method for eliminating this interference. Controlled experiments
using a Picarro G1101-i optical spectrometer were done to characterize the
H<sub>2</sub>S interference at varying CO<sub>2</sub> and H<sub>2</sub>S concentrations. The
addition of H<sub>2</sub>S to a CO<sub>2</sub> standard gas reveals an increase in the
<sup>12</sup>CO<sub>2</sub> concentration and a more significant decrease in the
<sup>13</sup>CO<sub>2</sub> concentration, resulting in a depleted δ<sup>13</sup>C
value. Reacting gas samples containing H<sub>2</sub>S with copper prior to
analysis can eliminate this effect. Models post-dating the G1101-i carbon
isotope analyzer have maintained the same spectral lines for CO<sub>2</sub> and
are likely to have a similar H<sub>2</sub>S response at elevated H<sub>2</sub>S
concentrations. It is important for future work with CRDS, particularly in
volcanic regions where H<sub>2</sub>S is abundant, to be aware of the H<sub>2</sub>S
interference on the CO<sub>2</sub> spectroscopic lines and to remove all H<sub>2</sub>S
prior to analysis. We suggest employing a scrub composed of copper to remove
H<sub>2</sub>S from all gas samples that have concentrations in excess of 1 ppb. |
| first_indexed | 2024-12-23T20:22:00Z |
| format | Article |
| id | doaj.art-c50dfae5bd4f42928c6224bf8584bde6 |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-23T20:22:00Z |
| publishDate | 2015-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-c50dfae5bd4f42928c6224bf8584bde62022-12-21T17:32:31ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482015-10-018104075408210.5194/amt-8-4075-2015H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometerK. Malowany0J. Stix1A. Van Pelt2G. Lucic3Department of Earth & Planetary Sciences, McGill University, Montreal, CanadaDepartment of Earth & Planetary Sciences, McGill University, Montreal, CanadaPicarro Inc., Santa Clara, CA, USADepartment of Earth & Planetary Sciences, McGill University, Montreal, CanadaCavity ring-down spectrometers (CRDSs) have the capacity to make isotopic measurements of CO<sub>2</sub> where concentrations range from atmospheric (~ 400 ppm) to 6000 ppm. Following field trials, it has come to light that the spectrographic lines used for CO<sub>2</sub> have an interference with elevated (higher than ambient) amounts of hydrogen sulfide (H<sub>2</sub>S), which causes significant depletions in the δ<sup>13</sup>C measurement by the CRDSs. In order to deploy this instrument in environments with elevated H<sub>2</sub>S concentrations (i.e., active volcanoes), we require a robust method for eliminating this interference. Controlled experiments using a Picarro G1101-i optical spectrometer were done to characterize the H<sub>2</sub>S interference at varying CO<sub>2</sub> and H<sub>2</sub>S concentrations. The addition of H<sub>2</sub>S to a CO<sub>2</sub> standard gas reveals an increase in the <sup>12</sup>CO<sub>2</sub> concentration and a more significant decrease in the <sup>13</sup>CO<sub>2</sub> concentration, resulting in a depleted δ<sup>13</sup>C value. Reacting gas samples containing H<sub>2</sub>S with copper prior to analysis can eliminate this effect. Models post-dating the G1101-i carbon isotope analyzer have maintained the same spectral lines for CO<sub>2</sub> and are likely to have a similar H<sub>2</sub>S response at elevated H<sub>2</sub>S concentrations. It is important for future work with CRDS, particularly in volcanic regions where H<sub>2</sub>S is abundant, to be aware of the H<sub>2</sub>S interference on the CO<sub>2</sub> spectroscopic lines and to remove all H<sub>2</sub>S prior to analysis. We suggest employing a scrub composed of copper to remove H<sub>2</sub>S from all gas samples that have concentrations in excess of 1 ppb.http://www.atmos-meas-tech.net/8/4075/2015/amt-8-4075-2015.pdf |
| spellingShingle | K. Malowany J. Stix A. Van Pelt G. Lucic H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer Atmospheric Measurement Techniques |
| title | H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer |
| title_full | H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer |
| title_fullStr | H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer |
| title_full_unstemmed | H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer |
| title_short | H<sub>2</sub>S interference on CO<sub>2</sub> isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer |
| title_sort | h sub 2 sub s interference on co sub 2 sub isotopic measurements using a picarro g1101 i cavity ring down spectrometer |
| url | http://www.atmos-meas-tech.net/8/4075/2015/amt-8-4075-2015.pdf |
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