Sampling Artifacts from Conductive Silicone Tubing

We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: (1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and (2) silicone tubing emits org...

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Bibliographic Details
Published in:Aerosol science and technology 2009-09, Vol.43 (9), p.855-865
Main Authors: Timko, Michael T., Yu, Zhenhong, Kroll, Jesse, Jayne, John T., Worsnop, Douglas R., Miake-Lye, Richard C., Onasch, Timothy B., Liscinsky, David, Kirchstetter, Thomas W., Destaillats, Hugo, Holder, Amara L., Smith, Jared D., Wilson, Kevin R.
Format: Article
Language:English
Subjects:
Aerosols
Carbon
Carbon dioxide
Chemistry
Colloidal state and disperse state
Emission measurements
Emissions
Exact sciences and technology
Experiments
Filters
General and physical chemistry
Particulates
Q1
Silicon
silicones
Solvents
Surface physical chemistry
Temperature
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Summary:We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: (1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and (2) silicone tubing emits organic contaminants containing siloxane that are adsorbed onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosol mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and the tubing should, therefore, be used with caution. Contamination associated with the use of silicone tubing was observed at ambient temperature and, in some cases, was enhanced by mild heating (
ISSN:0278-6826
1521-7388
DOI:10.1080/02786820902984811