Chemistry and Physics Faculty Articles

Title

Evidence for High Molecular Weight Nitrogen-Containing Organic Salts in Urban Aerosols

Document Type

Article

Publication Date

8-1-2005

Publication Title

Environmental Science & Technology

ISSN

0013-936X

Volume

44

Issue/No.

12

First Page

4441

Last Page

4446

Abstract

High molecular weight (Mw) species were observed at substantial intensities in the positive-ion mass spectra in urban Shanghai aerosols collected from a single-particle time-of-flight mass spectrometer (in the m/z range 250−500) during three separate periods over 2007−2009. These species correlate well with the CN− mass signal, suggesting that C−N bonds are prevalent and that the observed high-Mw species are potentially nitrogen-containing organic salts. Anti-correlation with the ambient O3 concentration suggests that photochemical oxidants are not involved directly in the formation of these species. The Mannich reaction, among amines (or ammonia), formaldehyde, and carbonyls with an adjacent, acidic proton, is proposed as a plausible pathway leading to these organic salts. Although the high-Mw species observed in the single-particle mass spectra appear to be nitrogen-containing organics, further chemical confirmation is desired to verify if the proposed Mannich reaction can explain the formation of these high-Mw species in regions where ammonia, amines, and carbonyls are prevalent.

Comments

©2010 American Chemical Society

DOI

10.1021/es1001117

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Peer Reviewed

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