Comparison of negative-ion proton-transfer with iodide ion chemical ionization mass spectrometry for quantification of isocyanic acid in ambient air

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dc.contributor.authorWoodward-Massey, Robert
dc.contributor.authorTaha, Youssef M.
dc.contributor.authorMoussa, Samar G.
dc.contributor.authorOsthoff, Hans D.
dc.date.accessioned2021-06-29T02:47:58Z
dc.date.available2021-06-29T02:47:58Z
dc.date.issued2014-09-06
dc.description.abstractIsocyanic acid (HNCO) is a trace gas pollutant of potential importance to human health whose measurement has recently become possible through the development of negative-ion proton-transfer chemical ionization mass spectrometry (NI-PT-CIMS) with acetate reagent ion. In this manuscript, an alternative ionization and detection scheme, in which HNCO is quantified by iodide CIMS (iCIMS) as a cluster ion at m/z 170, is described. The sensitivity was inversely proportional to water vapor concentration but could be made independent of humidity changes in the sampled air by humidifying the ion–molecule reaction (IMR) region of the CIMS. The performance of the two ionization schemes was compared and contrasted using ambient air measurements of HNCO mixing ratios in Calgary, AB, Canada, by NI-PT-CIMS with acetate reagent ion from Dec 16 to 20, 2013, and by the same CIMS operated in iCIMS mode from Feb 3 to 7, 2014. The iCIMS exhibited a greater signal-to-noise ratio than the NI-PT-CIMS, not because of its sensitivity, which was lower (∼0.083 normalized counts per second (NCPS) per parts-per-trillion by volume (pptv) compared to ∼9.7 NCPS pptv−1), but because of a much lower and more stable background (3 ± 4 compared to a range of ∼2 × 103 to ∼6 × 103 NCPS). For the Feb 2014 data set, the HNCO mixing ratios in Calgary air ranged from <12 to 94 pptv (median 34 pptv), were marginally higher at night than during day, and correlated with nitrogen oxide (NOx = NO + NO2) mixing ratios and submicron particle volume. The ratios of HNCO to NOx observed are within the range of emission ratios reported for gasoline-powered motor vehicles.en_US
dc.description.grantingagencyNatural Sciences and Engineering Research Council (NSERC)en_US
dc.identifier.citationWoodward-Massey, R., Taha, Y. M., Moussa, S. G., & Osthoff, H. D. (2014). Comparison of negative-ion proton-transfer with iodide ion chemical ionization mass spectrometry for quantification of isocyanic acid in ambient air. Atmospheric Environment, 98, 693–703. doi:10.1016/j.atmosenv.2014.09.014en_US
dc.identifier.doihttp://dx.doi.org/10.1016/j.atmosenv.2014.09.014en_US
dc.identifier.urihttp://hdl.handle.net/1880/113557
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.publisher.departmentChemistryen_US
dc.publisher.facultyScienceen_US
dc.publisher.hasversionacceptedVersionen_US
dc.publisher.institutionUniversity of Calgaryen_US
dc.publisher.policyhttps://www.elsevier.com/journals/atmospheric-environment/1352-2310/open-access-optionsen_US
dc.rightsUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0en_US
dc.subjectIsocyanic aciden_US
dc.subjectChemical ionization mass spectrometryen_US
dc.subjectIodid reagent ionen_US
dc.subjectNegative-ion proton-transferen_US
dc.subjectUrban pollutionen_US
dc.titleComparison of negative-ion proton-transfer with iodide ion chemical ionization mass spectrometry for quantification of isocyanic acid in ambient airen_US
dc.typejournal articleen_US
ucalgary.item.requestcopytrueen_US
ucalgary.scholar.levelFacultyen_US
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