Title: Effects of gas–wall partitioning in Teflon tubing and instrumentation on time-resolved measurements of gas-phase organic compounds

Abstract

Recent studies have demonstrated that organic compounds can partition from the gas phase to the walls in Teflon environmental chambers and that the process can be modeled as absorptive partitioning. Here these studies were extended to investigate gas–wall partitioning of organic compounds in Teflon tubing and inside a proton-transfer-reaction mass spectrometer (PTR-MS) used to monitor compound concentrations. Rapid partitioning of C₈–C₁₄ 2-ketones and C₁₁–C₁₆ 1-alkenes was observed for compounds with saturation concentrations (c^*) in the range of 3×10⁴ to 1×10⁷µgm^-3, causing delays in instrument response to step-function changes in the concentration of compounds being measured. These delays vary proportionally with tubing length and diameter and inversely with flow rate and c^*. The gas–wall partitioning process that occurs in tubing is similar to what occurs in a gas chromatography column, and the measured delay times (analogous to retention times) were accurately described using a linear chromatography model where the walls were treated as an equivalent absorbing mass that is consistent with values determined for Teflon environmental chambers. The effect of PTR-MS surfaces on delay times was also quantified and incorporated into the model. The model predicts delays of an hour or more for semivolatile compounds measured under commonly employed conditions. Thesemore » results and the model can enable better quantitative design of sampling systems, in particular when fast response is needed, such as for rapid transients, aircraft, or eddy covariance measurements. They may also allow estimation of c^* values for unidentified organic compounds detected by mass spectrometry and could be employed to introduce differences in time series of compounds for use with factor analysis methods. Best practices are suggested for sampling organic compounds through Teflon tubing.« less

Authors:

Pagonis, Demetrios ;

• Search DOE PAGES for author "Pagonis, Demetrios"
• Search DOE PAGES for ORCID "0000-0002-0441-2614"

Krechmer, Jordan E. ;

• Search DOE PAGES for author "Krechmer, Jordan E."
• Search DOE PAGES for ORCID "0000-0003-3642-0659"

de Gouw, Joost ;

• Search DOE PAGES for author "de Gouw, Joost"
• Search DOE PAGES for ORCID "0000-0002-0385-1826"

Jimenez, Jose L. ;

• Search DOE PAGES for author "Jimenez, Jose L."
• Search DOE PAGES for ORCID "0000-0001-6203-1847"

Ziemann, Paul J.

• Search DOE PAGES for author "Ziemann, Paul J."
• Search DOE PAGES for ORCID "0000-0001-7419-0044"

Publication Date:

Mon Dec 04 00:00:00 EST 2017

Research Org.:

Univ. of Colorado, Boulder, CO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1458837

Alternate Identifier(s):

OSTI ID: 1502928

Grant/Contract Number:  

SC0016559

Resource Type:

Published Article

Journal Name:

Atmospheric Measurement Techniques (Online)

Additional Journal Information:

Journal Name: Atmospheric Measurement Techniques (Online) Journal Volume: 10 Journal Issue: 12; Journal ID: ISSN 1867-8548

Publisher:

Copernicus Publications, EGU

Country of Publication:

Germany

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES