Talk:Flowing afterglow mass spectrometry
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One of the first papers reporting the use of flowing afterglow (FA) was reported in Planet Space Sci in 1966 by Norton, Ferguson, Fehsenfeld, and Schmeltekopf. They studied ion-molecule reactions pertient in the Martian atmosphere. This flowing afterglow replaced the stationary flowing afterglow. The flowing afterglow has many attractive aspects: well-understood laminar, viscous gas flow, a large number density of carrier gas which allows the study of thermalized reactions, and the cabability to make new reactant ions in situ. The ambipolar plasma is sampled using a nosecone and detected using a conventional quadrupole or tandem mass spectrometry, depending on the application. One of the drawbacks of the flowing afterglow is the possiblity of generating multiple reactant ions. This problem was cicumvented by implementing the selected ion flow tube (SIFT).
The flowing afterglow can be used to identify and quantify the VOCs of a sample as long as the fundamental ion chemistry is known. The commonly used ions are H3O+, O2+, and NO+. All ions have drawbacks and advantages. Strategies that have been employed to unequivocally identify the VOCs are to use GC coupled with the FA or to use a complement of reagent ions. Detection limits are typically ppb if there is limited sample or ppt if there is unlimited sample.
