SMOG chambers are widely used in laboratory studies of aerosol formation and evolution under complex air pollution scenarios. In a recent study conducted at CSIRO Energy in NSW, Australia (Li et al., 2018), a mixture of aromatic hydrocarbons, NH3, and other oxidation products were successfully monitored by SIFT-MS to study aerosol nucleation and growth process with the intention to assess the contribution of NH3 to aerosol formation which is a newly emerged topic of interest related to severe haze events in China.
SIFT-MS’s multiple reagent ion switching capability coupled with high accuracy and real time data in VOC quantification makes it an adaptable tool for SMOG chamber-based research
Image Courtesy: National Science Foundation
The experiments were carried out in a 26.76-m3 smog chamber and the gases (NH3, NO2 and NO) were injected into the chamber at controlled flow rates. Known amounts of hydrocarbons were supplied at sub-200 ppb (by volume) concentrations over a 10-minute period in a flow of nitrogen. Mixed ultraviolet lamps (80 in total) were used to yield desired levels of photolysis rates.
SIFT-MS’s core benefit – availability of multiple reagent ions (H3O+, NO+ and O2+) and precise soft ionization of analyte VOCs – enabled the researchers to easily monitor aerosol formation. The data generated were validated by comparison with simulated concentrations of the monitored gaseous species (figure 1). SIFT-MS produced data with very high time resolution and matched the model output with great accuracy at low ppb levels.
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