Measurement of the gas phase concentration of H₂SO₄ and methane sulfonic acid and estimates of H₂SO₄ production and loss in the atmosphere

Abstract

Measurements of gas phase sulfuric and methane sulfonic acid (MSA) have been performed using a relatively new atmospheric pressure selected ion chemical ionization mass spectrometric technique at two field sites. Both gas phase acids are photooxidation products, and their concentrations are seen to qualitatively follow solar flux. While sulfuric acid concentrations typically decline in conjunction with declining solar radiation, they sometimes level off in the mid 105–106 molecules cm−3 range after dark, even in relatively clean air. The reason for this quasi‐stable nighttime sulfuric acid concentration is not well understood but may be a result of a steady state exchange of sulfuric acid between particles and the gas phase. Measurements of OH, H2SO4, and SO2 concentrations in conjunction with aerosol number and size distribution also made possible the independent calculation of gas phase sulfuric acid production and loss rates. Calculated production and loss rates are seen to agree well in relatively clean air during the daylight hours. At night, however, the sulfuric acid concentrations and its calculated loss rate often have a nonzero value. In more polluted air masses, calculated gas phase sulfuric acid losses significantly exceed calculated production if H2SO4/aerosol reaction probabilities of 1.0 or 0.5 are assumed.

A Chemical Ionization Mass Spectrometer for ambient measurements of Ammonia

“…1a). The third part of the CIMS (vacuum region) is similar to that of the Georgia Tech NH 3 -CIMS (Nowak et al, 2006(Nowak et al, , 2007 and of the H 2 SO 4 -CIMS described elsewhere (Eisele and Tanner, 1993;Slusher et al, 2004;Benson et al, 2008;Young et al, 2008). The CDC and octopole ion guide dramatically improve the cleanness of ion mass spectra and the instrument sensitivity ( Fig.…”

Hydrates in binary sulfuric acid‐water vapor: Comparison of CIMS measurements with the Liquid‐Drop Model

“…and their hydrates [Eisele and Tanner, 1993]. As shown below, clusters containing two or more acid molecules can also be evaluated using the liquid-drop model.…”

Bisulfate – cluster based atmospheric pressure chemical ionization mass spectrometer for high-sensitivity (< 100 ppqV) detection of atmospheric dimethyl amine: proof-of-concept and first ambient data from boreal forest

“…This observation, albeit qualitative, indicates that DMA/EA and DEA/BA can be detected with higher sensitivity than ammonia and other small amines, because the "trimer" concentration in the system is significantly higher than that of the "tetramer" and larger sulfuric acid clusters. Figure 3 shows the operation of the NO − 3 CI-system in more detail (Eisele and Tanner, 1993;Jokinen et al, 2011), including COMSOL computational fluid dynamical modelling. The system is comprised of a 3/4 inlet tube through which the sample is drawn with a flow rate of 10 L min −1 .…”

“…For acids, such as sulfuric acid, detection limits down to 1 ppqV have been achieved with the APCI-MS technique when the nitrate ion has been used as the primary ion (e.g. Eisele and Tanner, 1993;Jokinen et al, 2012). With the APCI-MS technique, interference from compounds in particle phase is minimized, whereas, in techniques utilizing sample collection and subsequent analysis (e.g.…”