Determination of Diffusive Uptake Rates for VOCs on Passive Thermal Desorption Air Samplers

Sorbent tube air sampling is an accepted and reliable method for the analysis of Volatile Organic Compounds (VOCs) in the air we breathe. While active sampling (pumped) can readily deliver air compound concentrations, passive sampling (driven by diffusion) requires the use of uptake rates, which account for the rate at which compounds enter the sampler and adhere to its sorbent. The scientific literature contains few published uptake rates. As such, it was the goal of this research to measure the uptake rates of potentially harmful VOCs. This method employed a technique of simultaneous active and passive sampling to calculate uptake rates. Initial experimentation delivered uptake rates for benzene, toluene, ethylbenzene, and m/p-xylene for a sample period of 24 hours, and upon literature comparison, these data are supportive of the method conducted. Further development of uptake rates will enable the analysis of passively sampled compounds previously unquantifiable. This will allow for the assessment of human health risk from chronic exposure to these compounds, which passive sampling better represents in comparison to active sampling. It will also be possible to retrospectively analyze results obtained from the 2019 NASA/NOAA FIREX-AQ campaign, a study of wildfire and biomass burning emissions in the United States