Preprints
https://doi.org/10.5194/amt-2024-94
https://doi.org/10.5194/amt-2024-94
21 Jun 2024
 | 21 Jun 2024
Status: this preprint is currently under review for the journal AMT.

Calibration of Hydroxyacetonitrile (HOCH2CN) and Methyl isocyanate (CH3NCO) Isomers using I- Chemical Ionization Mass Spectrometry (CIMS)

Zachary Finewax, Aparajeo Chattopadhyay, J. Andrew Neuman, James Roberts, and James Burkholder

Abstract. The toxic reduced nitrogen compound methyl isocyanate (CH3NCO, MIC) has been reported present in wildfire and bio-mass burning emissions, agricultural fumigation plumes, and indoor air. Its isomer, hydroxyacetonitrile (HOCH2CN, glycolonitrile, HAN) has not been observed in the Earth’s atmosphere to date. In this study, absolute sensitivity calibrations for these isomers using two I- chemical ionization mass spectrometry (I-CIMS) instruments, time-of-flight (ToF) and quadrupole (Quad) instruments, commonly used in laboratory and field measurements, were performed, for the first time, over a range of ion-molecule reactor temperature (10–40 °C) and I(H2O)-/I- ratio (0.01–1). This study demonstrates that I-CIMS, under typical operating conditions, is not sensitive to MIC with limits of detection (LOD) of >860 and >570 ppb for the ToF and Quad I-CIMS instruments, respectively. Both I-CIMS instruments are, however, highly sensitive to the HAN isomer with 0.3 and 3 ppt LODs for the ToF-CIMS and Quad-CIMS instruments, respectively. These results contradict several recent field studies that have reported the detection of MIC using I-CIMS instruments. This study demonstrates that HAN, rather than MIC, was most likely the C2H3NO isomer observed in those field studies, although the source chemistry for HAN remains uncharacterized.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Zachary Finewax, Aparajeo Chattopadhyay, J. Andrew Neuman, James Roberts, and James Burkholder

Status: open (until 20 Aug 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2024-94', Delphine Farmer, 21 Jun 2024 reply
Zachary Finewax, Aparajeo Chattopadhyay, J. Andrew Neuman, James Roberts, and James Burkholder
Zachary Finewax, Aparajeo Chattopadhyay, J. Andrew Neuman, James Roberts, and James Burkholder

Viewed

Total article views: 196 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
145 35 16 196 10 10
  • HTML: 145
  • PDF: 35
  • XML: 16
  • Total: 196
  • BibTeX: 10
  • EndNote: 10
Views and downloads (calculated since 21 Jun 2024)
Cumulative views and downloads (calculated since 21 Jun 2024)

Viewed (geographical distribution)

Total article views: 194 (including HTML, PDF, and XML) Thereof 194 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 18 Jul 2024
Download
Short summary
This work provides a comprehensive sensitivity calibration of a chemical ionization instrument commonly used in field measurements for the measurement of the toxic isomers methyl isocyanate and hydroxyacetonitrile that are found in the atmosphere. The results from this work has demonstrated that the hydroyacetonitrile isomer was observed in previous field studies rather than the stated identification of methyl isocyanate.