An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acids
An ion-neutral chemical kinetic model is described and used to simulate the negative ion chemistry occurring within a mixed-reagent ion chemical ionization mass spectrometer (CIMS). The model objective was the establishment of a theoretical basis to understand ambient pressure (variable sample f...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-04-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/11/1851/2018/amt-11-1851-2018.pdf |
| _version_ | 1818174455096016896 |
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| author | B. G. Heikes V. Treadaway A. S. McNeill A. S. McNeill I. K. C. Silwal I. K. C. Silwal D. W. O'Sullivan |
| author_facet | B. G. Heikes V. Treadaway A. S. McNeill A. S. McNeill I. K. C. Silwal I. K. C. Silwal D. W. O'Sullivan |
| author_sort | B. G. Heikes |
| collection | DOAJ |
| description | An ion-neutral chemical kinetic model is described and used to
simulate the negative ion chemistry occurring within a mixed-reagent ion
chemical ionization mass spectrometer (CIMS). The model objective was the
establishment of a theoretical basis to understand ambient pressure (variable
sample flow and reagent ion carrier gas flow rates), water vapor, ozone and
oxides of nitrogen effects on ion cluster sensitivities for hydrogen peroxide
(H<sub>2</sub>O<sub>2</sub>), methyl peroxide (CH<sub>3</sub>OOH), formic
acid (HFo) and acetic acid (HAc). The model development
started with established atmospheric ion chemistry mechanisms, thermodynamic
data and reaction rate coefficients. The chemical mechanism was augmented
with additional reactions and their reaction rate coefficients specific to
the analytes. Some existing reaction rate coefficients were modified to
enable the model to match laboratory and field campaign determinations of
ion cluster sensitivities as functions of CIMS sample flow rate and ambient
humidity. Relative trends in predicted and observed sensitivities are
compared as instrument specific factors preclude a direct calculation of
instrument sensitivity as a function of sample pressure and humidity.
Predicted sensitivity trends and experimental sensitivity trends suggested
the model captured the reagent ion and cluster chemistry and reproduced
trends in ion cluster sensitivity with sample flow and humidity observed with
a CIMS instrument developed for atmospheric peroxide measurements (PCIMSs).
The model was further used to investigate the potential for isobaric
compounds as interferences in the measurement of the above species. For
ambient O<sub>3</sub> mixing ratios more than 50 times those of
H<sub>2</sub>O<sub>2</sub>, O<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) was predicted to be a
significant isobaric interference to the measurement of H<sub>2</sub>O<sub>2</sub>
using O<sub>2</sub><sup>−</sup>(H<sub>2</sub>O<sub>2</sub>) at <i>m</i>∕<i>z</i> 66. O<sub>3</sub> and
NO give rise to species and cluster ions, CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)
and NO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O), respectively, which interfere in the
measurement of CH<sub>3</sub>OOH using
O<sub>2</sub><sup>−</sup>(CH<sub>3</sub>OOH) at <i>m</i>∕<i>z</i> 80. The
CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) interference assumed one of its <i>O</i> atoms
was <sup>18</sup>O and present in the cluster in proportion to its natural
abundance. The model results indicated monitoring water vapor mixing ratio,
<i>m</i>∕<i>z</i> 78 for CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) and <i>m</i>∕<i>z</i> 98 for isotopic
CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)<sub>2</sub> can be used to determine when
CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) interference is significant. Similarly,
monitoring water vapor mixing ratio, <i>m</i>∕<i>z</i> 62 for NO<sub>3</sub><sup>−</sup> and
<i>m</i>∕<i>z</i> 98 for NO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)<sub>2</sub> can be used to determine
when NO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) interference is significant. |
| first_indexed | 2024-12-11T19:44:40Z |
| format | Article |
| id | doaj.art-f50c8d9ca30b4884b97c0f3768736086 |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-11T19:44:40Z |
| publishDate | 2018-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-f50c8d9ca30b4884b97c0f37687360862022-12-22T00:52:56ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482018-04-01111851188110.5194/amt-11-1851-2018An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acidsB. G. Heikes0V. Treadaway1A. S. McNeill2A. S. McNeill3I. K. C. Silwal4I. K. C. Silwal5D. W. O'Sullivan6Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USAGraduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USAGraduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USADepartment of Chemistry, The University of Alabama, Tuscaloosa, AL 35401, USAChemistry Department, United States Naval Academy, Annapolis, MD 21402, USAForest Bioproducts Research Institute, University of Maine, Orono 04469, USAChemistry Department, United States Naval Academy, Annapolis, MD 21402, USAAn ion-neutral chemical kinetic model is described and used to simulate the negative ion chemistry occurring within a mixed-reagent ion chemical ionization mass spectrometer (CIMS). The model objective was the establishment of a theoretical basis to understand ambient pressure (variable sample flow and reagent ion carrier gas flow rates), water vapor, ozone and oxides of nitrogen effects on ion cluster sensitivities for hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), methyl peroxide (CH<sub>3</sub>OOH), formic acid (HFo) and acetic acid (HAc). The model development started with established atmospheric ion chemistry mechanisms, thermodynamic data and reaction rate coefficients. The chemical mechanism was augmented with additional reactions and their reaction rate coefficients specific to the analytes. Some existing reaction rate coefficients were modified to enable the model to match laboratory and field campaign determinations of ion cluster sensitivities as functions of CIMS sample flow rate and ambient humidity. Relative trends in predicted and observed sensitivities are compared as instrument specific factors preclude a direct calculation of instrument sensitivity as a function of sample pressure and humidity. Predicted sensitivity trends and experimental sensitivity trends suggested the model captured the reagent ion and cluster chemistry and reproduced trends in ion cluster sensitivity with sample flow and humidity observed with a CIMS instrument developed for atmospheric peroxide measurements (PCIMSs). The model was further used to investigate the potential for isobaric compounds as interferences in the measurement of the above species. For ambient O<sub>3</sub> mixing ratios more than 50 times those of H<sub>2</sub>O<sub>2</sub>, O<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) was predicted to be a significant isobaric interference to the measurement of H<sub>2</sub>O<sub>2</sub> using O<sub>2</sub><sup>−</sup>(H<sub>2</sub>O<sub>2</sub>) at <i>m</i>∕<i>z</i> 66. O<sub>3</sub> and NO give rise to species and cluster ions, CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) and NO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O), respectively, which interfere in the measurement of CH<sub>3</sub>OOH using O<sub>2</sub><sup>−</sup>(CH<sub>3</sub>OOH) at <i>m</i>∕<i>z</i> 80. The CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) interference assumed one of its <i>O</i> atoms was <sup>18</sup>O and present in the cluster in proportion to its natural abundance. The model results indicated monitoring water vapor mixing ratio, <i>m</i>∕<i>z</i> 78 for CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) and <i>m</i>∕<i>z</i> 98 for isotopic CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)<sub>2</sub> can be used to determine when CO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) interference is significant. Similarly, monitoring water vapor mixing ratio, <i>m</i>∕<i>z</i> 62 for NO<sub>3</sub><sup>−</sup> and <i>m</i>∕<i>z</i> 98 for NO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)<sub>2</sub> can be used to determine when NO<sub>3</sub><sup>−</sup>(H<sub>2</sub>O) interference is significant.https://www.atmos-meas-tech.net/11/1851/2018/amt-11-1851-2018.pdf |
| spellingShingle | B. G. Heikes V. Treadaway A. S. McNeill A. S. McNeill I. K. C. Silwal I. K. C. Silwal D. W. O'Sullivan An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acids Atmospheric Measurement Techniques |
| title | An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acids |
| title_full | An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acids |
| title_fullStr | An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acids |
| title_full_unstemmed | An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acids |
| title_short | An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules – application to a mixed reagent ion system for hydroperoxides and organic acids |
| title_sort | ion neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules ndash application to a mixed reagent ion system for hydroperoxides and organic acids |
| url | https://www.atmos-meas-tech.net/11/1851/2018/amt-11-1851-2018.pdf |
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