Analysis of ambient VOCs using thermal desorption gas chromatography to
identify smoke influence in urban areas
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.