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Characterization of Aerosol Nitro Aromatic Compounds Validation of an Experimental Method

Metadata Updated: November 12, 2020

The analytical capabilities associated with the use of silylation reactions have been extended to a new class of organic molecules, nitroaromatic compounds (NACs). These compounds are a possible contributor to urban particulate matter of secondary origin which would make them important analytes due to their (1) detrimental health effects, (2) potential to affect aerosol optical properties, (3) and usefulness for identifying PM2.5 from biomass burning. The technique is based on derivatization of the parent NACs using N,O-bis-(trimethylsilyl)-trifluoro acetamide, one of the most prevalent derivatization reagent for analyzing hydroxylated molecules, followed by GC-MS using electron ionization (EI) and methane chemical ionization (CI). This method is evaluated for 32 NACs including nitrophenols, methyl-/methoxy-nitrophenols, nitrobenzoic acids, and nitrobenzyl alcohols. EI spectra were characterized by a high abundance of ions corresponding to [M+.], or [M+ - 15]. CI spectra exhibited high abundance for [M+ + 1], [M+ - 15], and [M+ + 29] ions. Both EI and CI spectra exhibit ions specific to nitro group(s) for [M+. - 31], [M+. - 45], and [M+. - 60]. The strong abundance observed for [M+.] (EI), [M+ - 15] (EI/CI), or [M+ + 1] (CI) ions is consistent with the high charge stabilizing ability associated with aromatic compounds. The combination of EI and CI ionization offers strong capabilities for detection and identification of NACs. Spectra associated with NACs, containing hydrogen, carbon, oxygen, and nitrogen atoms only, as silylated derivatives show fragment/adduct ions at either (a) odd or (b) even masses that indicate either (a) odd or (b) even number of nitro groups, respectively. Mass spectra associated with silylated NACs exhibited three distinct regions where characteristic fragmentation with a specific pattern associated with: (1) -OH, and/or -COOH groups, (2) -NO2 group(s), and (3) benzene ring(s). These findings were confirmed with applications to chamber aerosol and ambient PM2.5.

This dataset is associated with the following publication: Jaoui, M., M. Lewandowski, J. Offenberg, M. Colon, K. Docherty, and T. Kleindienst. Characterization of aerosol nitroaromatic compounds: Validation of an experimental method. Journal of Mass Spectrometry. John Wiley & Sons, Ltd., Indianapolis, IN, USA, 53(8): 680-692, (2018).

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Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020

Metadata Source

Harvested from EPA ScienceHub

Additional Metadata

Resource Type Dataset
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Publisher U.S. EPA Office of Research and Development (ORD)
Data Last Modified 2018-05-01
Public Access Level public
Bureau Code 020:00
Schema Version
Harvest Object Id 9df13a9b-0b6d-4c32-96b8-f3c5f4d51523
Harvest Source Id 04b59eaf-ae53-4066-93db-80f2ed0df446
Harvest Source Title EPA ScienceHub
Program Code 020:094
Publisher Hierarchy U.S. Government > U.S. Environmental Protection Agency > U.S. EPA Office of Research and Development (ORD)
Related Documents
Source Datajson Identifier True
Source Hash 8c0f104d6cc82c5ed0a437c957dd0691d68792ee
Source Schema Version 1.1

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