TY  - JOUR
A1  - Obersteiner, Florian
A1  - Bönisch, Harald
A1  - Keber, Timo
A1  - O'Doherty, Simon
A1  - Engel, Andreas
T1  - A versatile, refrigerant- and cryogen-free cryofocusing–thermodesorption unit for preconcentration of traces gases in air
T2  - Atmospheric measurement techniques
N2  - We present a compact and versatile cryofocusing– thermodesorption unit, which we developed for quantitative analysis of halogenated trace gases in ambient air. Possible applications include aircraft-based in situ measurements, in situ monitoring and laboratory operation for the analysis of flask samples. Analytes are trapped on adsorptive material cooled by a Stirling cooler to low temperatures (e.g. -80°C) and subsequently desorbed by rapid heating of the adsorptive material (e.g. 200°C). The set-up involves neither the exchange of adsorption tubes nor any further condensation or refocusing steps. No moving parts are used that would require vacuum insulation. This allows for a simple and robust design. Reliable operation is ensured by the Stirling cooler, which neither contains a liquid refrigerant nor requires refilling a cryogen. At the same time, it allows for significantly lower adsorption temperatures compared to commonly used Peltier elements. We use gas chromatography – mass spectrometry (GC–MS) for separation and detection of the preconcentrated analytes after splitless injection. A substance boiling point range of approximately -80 to +150°C and a substance mixing ratio range of less than 1 ppt (pmol mol−1)to more than 500 ppt in preconcentrated sample volumes of 0.1 to 10 L of ambient air is covered, depending on the application and its analytical demands. We present the instrumental design of the preconcentration unit and demonstrate capabilities and performance through the examination of analyte breakthrough during adsorption, repeatability of desorption and analyte residues in blank tests. Examples of application are taken from the analysis of flask samples collected at Mace Head Atmospheric Research Station in Ireland using our laboratory GC–MS instruments and by data obtained during a research flight with our in situ aircraft instrument GhOSTMS (Gas chromatograph for the Observation of Tracers – coupled with a Mass Spectrometer).
Y1  - 2016
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/42442
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-424427
SN  - 1867-8548
SN  - 1867-1381
N1  - c Author(s) 2016. CC-BY 3.0 License.
VL  - 9
SP  - 5265
EP  - 5279
PB  - Copernicus
CY  - Katlenburg-Lindau [u.a.]
ER  -