Qualitative and quantitative analysis of atmospheric organosulfates in Centreville, Alabama

Abstract

Abstract. Organosulfates are components of secondary organic aerosols (SOA) that form from oxidation of volatile organic compounds (VOCs) in the presence of sulfate. In this study, the composition and abundance of organosulfates were determined in fine particulate matter (PM2.5) collected from Centreville, AL, during the Southern Oxidant and Aerosol Study (SOAS) in summer 2013. Six organosulfates were quantified using hydrophilic interaction liquid chromatography (HILIC) with triple quadrupole mass spectrometry (TQD) against authentic standards. Among these, the three most abundant species were glycolic acid sulfate (0.5–52.5 ng m−3), lactic acid sulfate (0.5–36.7 ng m−3), and hydroxyacetone sulfate (0.5–14.3 ng m−3). These three species were strongly inter-correlated, suggesting similar precursors and/or formation pathways. Further correlations with sulfate, isoprene, and isoprene oxidation products indicate important roles for these precursors in organosulfate formation in Centreville. Positive filter sampling artifacts associated with these organosulfates due to gas adsorption or reaction of gas phase precursors of organosulfates with sulfuric acid were assessed for a subset of samples and were less than 7.8 % of their PM2.5 concentrations. Together, the quantified organosulfates accounted for < 0.3 % of organic carbon mass in PM2.5. To gain insights into other organosulfates in PM2.5 collected from Centreville, semi-quantitative analysis was employed by way of monitoring characteristic product ions of organosulfates (HSO4− at m∕z 97 and SO4− ⋅ at m∕z 96) and evaluating relative signal strength by HILIC–TQD. Molecular formulas of organosulfates were determined by high-resolution time-of-flight (TOF) mass spectrometry. The major organosulfate signal across all samples corresponded to 2-methyltetrol sulfates, which accounted for 42–62 % of the total bisulfate ion signal. Conversely, glycolic acid sulfate, the most abundant organosulfate quantified in this study, was 0.13–0.57 % of the total bisulfate ion signal. Precursors of m∕z 96 mainly consisted of nitro-oxy organosulfates. Organosulfates identified were mainly associated with biogenic VOC precursors, particularly isoprene and to a lesser extent monoterpenes and 2-methyl-3-buten-2-ol (MBO). While a small number of molecules dominated the total organosulfate signal, a large number of minor species were also present. This study provides insights into the major organosulfate species in the southeastern US, as measured by tandem mass spectrometry that should be targets for future standard development and quantitative analysis.

Regional Differences of Chemical Composition and Optical Properties of Aerosols in the Tibetan Plateau

“…The reference lines indicate linear polyene (DBE = 0.5 * n C ), cata-PAHs (DBE = 0.75 * n C − 0.5), and fullerene-like hydrocarbons (DBE = 0.9 * n C ). High concentration of SO 2 with carbonyl compounds and PAH is susceptible to form sulfur-containing SOA (Hettiyadura et al, 2017;Staudt et al, 2014). Note that many points are overlapped together.…”

“…Under the urbanization and economic development in Western China, SO 2 emissions show an increasing trend in contrast to the decreasing trend in East China (Ling et al, 2017). High concentration of SO 2 with carbonyl compounds and PAH is susceptible to form sulfur-containing SOA (Hettiyadura et al, 2017;Staudt et al, 2014). Biomass burning emits large amount of nitrogen oxides (NO and NO 2 ; NO x ), and reactive volatile organic compounds such as phenolic compounds (Andreae & Merlet, 2001;Simoneit et al, 1993).…”

Online gas and particle phase measurements of organosulfates, organosulfonates and nitrooxyorganosulfates in Beijing utilizing a FIGAERO ToF-CIMS

“…Previous studies have supported the existence of gas phase GAS in ambient air (e.g. Ehn et al, 2010), although some work has attributed other measurement techniques detection of gas phase SCO to result from measurement artefacts (Hettiyadura et al, 2017;Kristensen et al, 2016). One possibility is the deposition of SCOs onto the IMR walls during the temperature ramp of the desorption which in time may de-gas and be observed in the gas phase.…”

“…GAS (Hettiyadura et al, 2017;Hansen et al, 2014). Burning events are known to emit high levels of organics and nitrates and potentially sulfur, depending on the type of fuel used.…”

“…This can limit the ability to evaluate production pathways when concentrations are often integrated over a period of hours. Further reactions on filters between the organics and sulfates has also been postulated to add a bias to the OS concentration measured with respect to initial deposition onto the filter 5 (Hettiyadura et al, 2017;Kristensen et al, 2016). Recently, a Particle Analysis Laser Mass Spectrometer (PALMS) was utilized to measure a number of OSs over the United States highlighting the ability of time of flight mass spectrometers to measure several OSs at high time frequencies (Liao et al, 2015).…”