1 research outputs found
Iodometry-Assisted Liquid Chromatography Electrospray Ionization Mass Spectrometry for Analysis of Organic Peroxides: An Application to Atmospheric Secondary Organic Aerosol
Organic
peroxides comprise a significant fraction of atmospheric
secondary organic aerosol (SOA). Detection and quantification of particle-phase
organic peroxides are highly challenging, and current efforts rely
significantly on filter extraction and offline mass spectrometry (MS).
Here, a novel technique, iodometry-assisted liquid chromatography
electrospray ionization mass spectrometry (iodometry-assisted LC-ESI-MS),
is developed and evaluated with a class of atmospherically relevant
organic peroxides, α-acyloxyalkyl hydroperoxides, synthesized
via liquid ozonolysis. Iodometry-assisted LC-ESI-MS unambiguously
distinguishes organic peroxides, compensating for the lack of functional
group information that can be obtained with MS. This technique can
be versatile for a wide spectrum of environmental analytical applications
for which a molecular-level identification of organic peroxide is
required. Here, iodometry-assisted LC-ESI-MS is applied to the water-soluble
organic carbon (WSOC) of α-pinene SOA. Unexpectedly, a limited
number of detectable compounds in WSOC appear to be organic peroxides,
despite the fact that spectroscopy-based iodometry indicates 15% of
WSOC mass is associated with organic peroxides. This observation would
be consistent with decomposition of multifunctional organic peroxides
to small peroxides that can be quantified by spectroscopy-based iodometry
but not by LC-ESI-MS. Overall, this study raises concerns regarding
filter extraction-based studies, showing that assignment of organic
peroxides solely on the basis of MS signatures can be misleading