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ANALYSIS OF AIRBORNE CARBOXYLIC ACIDS AND PHENOLS AS THEIR PENTAFLUOROBENZYL DERIVATIVES: GAS CHROMATOGRAPHY/ION TRAP MASS SPECTROMETRY WITH A NOVEL CHEMICAL IONIZATION REAGENT, PFBOH. (R826247)
Citation:
Chien, C. J., M. J. Charles, K. G. Sexton, AND H. E. Jeffries. ANALYSIS OF AIRBORNE CARBOXYLIC ACIDS AND PHENOLS AS THEIR PENTAFLUOROBENZYL DERIVATIVES: GAS CHROMATOGRAPHY/ION TRAP MASS SPECTROMETRY WITH A NOVEL CHEMICAL IONIZATION REAGENT, PFBOH. (R826247). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 32(2):299-309, (1998).
Description:
The complex photochemical transformations of biogenic
hydrocarbons such as isoprene and of anthropogenic
hydrocarbons such as aromatics are an important source
of carboxylic acids in the troposphere. The
identification
of unknown carboxylic acids can be difficult, however, due
to the lack of standards as well as poor sensitivity and
lack of selectivity of existing techniques. In this study,
we
describe the development of a method to analyze airborne
carboxylic acids using derivatization with
pentafluorobenzyl bromide (PFBBr) followed by capillary
gas chromatography/ion trap mass spectrometry (GC/ITMS) analysis. In addition to the typical electron
impact
ionization (EI) and methane chemical ionization (CI) mass
spectra of pentafluorobenzyl derivatives, we describe the
use of pentafluorobenzyl alcohol (PFBOH) as a novel
reagent gas for CIMS. Pentafluorobenzyl ions (m/z =
181)
were produced at reduced pressure (1 × 10-5-2 ×
10-5
Torr) from PFBOH gas, and the resulting CIMS were
characterized by the predominance of the [M + 181]+
ions.
The carboxylic acid products in the oxidation of
isoprene
from indoor and outdoor smog chamber experiments
were analyzed using the described PFBBr GC/ITMS method.
The formation of methacrylic acid in an isoprene/O3
reaction
was demonstrated experimentally for the first time, and
acrylic acid, one of the U.S. EPA 189 Hazardous Air
Pollutants,
is first reported here as an isoprene oxidation product.
In other outdoor toluene/NOx chamber
experiments, we
detected a series of carboxylic acids and various phenolic
compounds using this method.