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Analysis of ambient VOCs using thermal desorption gas chromatography to identify smoke influence in urban areas
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  • Praphulla Chandra Boggarapu,
  • Crystal McClure,
  • JoAnne Mulligan,
  • Dan Jaffe
Praphulla Chandra Boggarapu
University of Washington, Bothell

Corresponding Author:[email protected]

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Crystal McClure
University of Washington, Bothell
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JoAnne Mulligan
University of Washington, Bothell
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Dan Jaffe
University of Washington, Bothell
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Abstract

Smoke influence in urban areas is relatively easy to detect at high concentrations, but more challenging to detect at low concentrations. For this reason, we have evaluated an approach using thermal desorption gas chromatography mass spectrometry (TD-GC-MS) to detect volatile organic compounds (VOCs) in particular oxygenated VOCs in urban areas. The goal of this work is to develop a method that can reliably quantify smoke tracers in an urban environment at relatively low cost and complexity. We present here the development and validation of a double-bedded thermal desorption tube with an auto sampler to collect continuous samples of VOCs. To evaluate the method performance, we have tested stability during storage, interferences (e.g., water and O3), and reproducibility for six VOCs, namely, acetonitrile, acetone, pentane, iso-pentane, benzene, and toluene. The results demonstrate that these can be quantified reproducibly with an error ≤ 20% between the collection and analysis with a storage time of up to 21 days. For acetone, similar results were obtained until day 14. Calibration experiments performed over a dynamic range of 10–150 ng loaded over thermal desorption tubes at different relative humidity showed excellent linearity (r2 ≥ 0.91). At this time, we are utilizing this method during the summer 2019 FIREX-AQ intensive experiment at the Boise ground site in Idaho. These results will be presented along with the quality control data.