Effect of relative humidity on the detection of sulfur dioxide and sulfuric acid using a chemical ionization mass spectrometer

Effect of relative humidity on the detection of sulfur dioxide and sulfuric acid using a chemical ionization mass spectrometer

Detection of sulfur dioxide and sulfuric acid at high relative humidity was studied using a chemical ionization mass spectrometer (CIMS). The reactant ions used in the experiments are CO 3 −· nH 2O ( n=0–5), which react with SO 2 to form SO 5 −· nH 2O ( n=0–2). H 2SO 4 reacts with the precursor ions...

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Bibliographic Details
Published in:International journal of mass spectrometry Vol. 231; no. 1; pp. 17 - 30
Main Authors: Salcedo, D., Villalta, P.W., Varutbangkul, V., Wormhoudt, J.C., Miake-Lye, R.C., Worsnop, D.R., Ballenthin, J.O., Thorn, W.F., Viggiano, A.A., Miller, T.M., Flagan, R.C., Seinfeld, J.H.
Format: Journal Article
Language:English
Published: Elsevier B.V 2004
Subjects:
Chemical ionization mass spectrometer
Relative humidity
Sulfur dioxide
Sulfuric acid
Water clusters
Relative humidity
Chemical ionization mass spectrometer
Water clusters
Sulfur dioxide
Sulfuric acid
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Summary:Detection of sulfur dioxide and sulfuric acid at high relative humidity was studied using a chemical ionization mass spectrometer (CIMS). The reactant ions used in the experiments are CO 3 −· nH 2O ( n=0–5), which react with SO 2 to form SO 5 −· nH 2O ( n=0–2). H 2SO 4 reacts with the precursor ions to form HSO 4 − ( m/ z=97 amu) and H 2SO 4·CO 3 − ( m/ z=158 amu). We report the first use of the latter ionization scheme to detect sulfuric acid. High RH affects the detection of SO 2 and H 2SO 4 by forming clusters with the reactant and product ions, reducing sensitivity. Increasing the temperature breaks these clusters. For SO 2 at high RH, either SO 5 − ( m/ z=112 amu) or SO 5 −·H 2O ( m/ z=130 amu) can be used for SO 2 detection without a decrease in sensitivity. For H 2SO 4 at high RH, it is preferred to detect the ion H 2SO 4·CO 3 − because the background signal at 158 amu is small, and a better sensitivity can be achieved.
ISSN:1387-3806
1873-2798
DOI:10.1016/j.ijms.2003.09.005