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| Titel |
Using Comprehensive Two-dimensional Gas Chromatography (GCxGC) for the Analysis of Volatile Organic Compounds (VOCs) |
| VerfasserIn |
R. T. Lidster, J. F. Hamilton, A. C. Lewis, J. D. Lee, J. R. Hopkins, S. Punjabi |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064780
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| Zusammenfassung |
| Volatile organic compounds (VOC) play an important role in atmospheric chemistry through
their contribution to the formation of ozone and secondary organic aerosol, both of which
may lead to human health impacts. VOC monitoring and quantification has traditionally used
techniques like gas chromatography and mass spectrometry, with methods developed to
target specific groups of compounds. However studies have shown that in some
locations the VOC loading in the atmosphere is not fully accounted for. Comprehensive
two-dimensional Gas chromatography (GCÃGC) utilises two columns coupled via a
modulator and can give rise to significant increases in resolution and peak capacity. Used in
combination with mass spectrometry it makes a powerful tool for complex sample
analysis. Unfortunately GCÃGC has found only limited application in atmospheric
chemistry due to the instrument size, expense, power consumption and cryogen
requirement.
GCÃGC-TOF/MS has been used to analyse Whole Air Samples (WAS) collected onboard the
FAAM research aircraft as part of the “ROle of Nighttime chemistry in controlling the
Oxidising Capacity of the AtmOsphere” (RONOCO) campaign. RONOCO studied the
transformation of pollutants during nightime over the UK and North Sea. GCxGC
results have shown good agreement with an established GC-FID instrument and the
comprehensive analysis has allowed for the identification and quantification of additional
species not covered by the GC-FID system. The higher molecular weight aromatic
compounds detected showed a strong correlation with toluene and this has enabled the
calculation of proportionally factors. The additional reactive carbon identified using
GCÃGC is calculated to provide a large OH sink and may account for some of
the missing reactivity seen in previous studies. A number of additional NO3 sink
compounds were also identified, although their impact is likely to be small due to their
reactivity. Further work has also been carried out on the development of a valve based
GCÃGC-FID system, which does not require liquid nitrogen or the power & vacuum needs
of a mass spectrometer, as a methodology which may be taken directly in to the
field. |
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