Title: A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

Abstract

Here, we present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography–mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arranged into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. Amore » six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level resolution on other bulk aerosol components commonly observed by the AMS.« less

Authors:

Zhang, Yaping ^[1]; Williams, Brent J. ^[1]; Goldstein, Allen H. ^[2]; Docherty, Kenneth S. ^[3]; Jimenez, Jose L. ^[4]

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+ Show Author Affiliations

1. Washington Univ., St. Louis, MO (United States)
2. Univ. of California, Berkeley, CA (United States)
3. Univ. of Colorado, Boulder, CO (United States); Alion Science and Technology, Research Triangle Park, NC (United States)
4. Univ. of Colorado, Boulder, CO (United States)

Publication Date:

Fri Nov 25 00:00:00 EST 2016

Research Org.:

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

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1360108

Grant/Contract Number:  

SC0011105

Resource Type:

Accepted Manuscript

Journal Name:

Atmospheric Measurement Techniques (Online)

Additional Journal Information:

Journal Name: Atmospheric Measurement Techniques (Online); Journal Volume: 9; Journal Issue: 11; Journal ID: ISSN 1867-8548

Publisher:

European Geosciences Union

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY