Document Detail

A Novel Application of Time-of-Flight Aerosol Mass Spectrometry for the Online Measurement of Gaseous Molecular Iodine.
MedLine Citation:
PMID:  22243548     Owner:  NLM     Status:  Publisher    
Here we present a new application of a Time-of-Flight Aerosol Mass Spectrometer (ToF-AMS) for the measurement of atmospheric trace gases in real-time. Usually, ToF-AMS instruments are not sensitive to gas-phase species due to the aerodynamic particle focusing inlet system which reduces gas phase species by a factor of about 10<sup>7</sup> relative to the particle phase. This efficient removal of the gas phase and the resulting high relative enrichment of particles is one reason for the very high sensitivity of ToF-AMS instruments for particle phase compounds (detection limits in the sub-µg/m<sup>3</sup>-range for online measurements with 1 minute integration time), which allows application of the instruments even under clean atmospheric conditions. Here we use artificially generated particles as sampling probes to transfer selected atmospheric trace gases into the particle phase before entering the AMS (Gaseous compound TRapping in Artificially-generated Particles - AMS; GTRAP-AMS). The sampling probe particles are mixed with the gaseous analytes upstream the ToF-AMS in a 0.5 L flow tube. As an exemplary application of the method the measurement of trace levels of gaseous molecular iodine is demonstrated. α-Cyclodextrin (α-CD/NH<sub>4</sub>Br) particles are used as selective sampling probes to transfer molecular iodine into the AMS. A detection limit in the sub-ppb range was achieved. The method was compared to a recently developed off-line method that combines denuder sampling of gaseous I<sub>2</sub> and GC-MS analysis. To demonstrate the usability of the method temporally resolved I<sub>2</sub> emission profiles from a brown algae species (Laminaria Saccharina) under exposure of ambient ozone levels were investigated. Total I<sub>2</sub> release rates of 36.5 pmol min<sup>-1</sup> gFW<sup>-1</sup> at 100 pbb O<sub>3</sub> and 33.4 pmol min<sup>-1</sup> gFW<sup>-1</sup> at 50 ppb O<sub>3</sub> were obtained within the first hour of ozone exposure.
Michael Kundel; Ru-Jin Huang; Ute Rita Thorenz; Janine Bosle; Moritz Julian David Mann; Marco Ries; Thorsten Hoffmann
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-12-15
Journal Detail:
Title:  Analytical chemistry     Volume:  -     ISSN:  1520-6882     ISO Abbreviation:  -     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2012-1-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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