 |
| Titel |
Distinguishing Aldehydes and Ketones in Ambient Air using SIFT-MS |
| VerfasserIn |
D. R. Hastie, M. J. McEwan, D. B. Milligan, J. Gray, V. S. Langford |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022380
|
|
|
|
|
|
| Zusammenfassung |
| Aldehydes and ketones are the first generation products of atmospheric hydrocarbon
oxidation. As such their measurement is a key component in the testing of our current
understanding of atmospheric chemistry leading to ozone production.
Trap and analyse methods have been successful for analyzing these species but the rapid
chemistry of their production and loss drives the need for measurements on the minute time
scale. Mass spectrometric methods have the advantage of wide applicability to the
hydrocarbons and the carbonyl compounds with fast time response. However, since
this is fundamentally a mass measurement, these methods often cannot distinguish
between structural isomers on the basis of the parent ion alone. This is a particular
problem for the carbonyl compounds such as methacrolein and methylvinyl ketone
produced from the oxidation of isoprene as the aldehyde and ketone have the same
mass.
SIFT-MS is a mass spectrometric method that uses three different reagent ions, H3O+, NO+
and O2+ for chemical ionization of ambient samples. While the reaction of structural
isomers with H3O+ produces the same parent ion, the reactions with the other reagent
ions are different allowing rapid, real time measurements of structurally isomeric
carbonyls.
We will discuss the methodology of this technique and some preliminary ambient
measurements taken in a small city. |
|
|
|
|
|
|