An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air

  • We present the characterization and application of a new gas chromatography time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δm of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found to be approximately 5 ppm in mean after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits are as low as a few femtograms by means of the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. Detector non-linearity was found to be insignificant up to a mixing ratio of roughly 150 ppt at 0.5 L sampled volume. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straightforward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, quadrupole MS with low mass resolving power and a TOFMS technique reported to be non-linear and restricted by a small dynamical range.

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Metadaten
Author:Florian Obersteiner, Harald Bönisch, Andreas EngelORCiD
URN:urn:nbn:de:hebis:30:3-424599
DOI:https://doi.org/10.5194/amtd-8-9455-2015
ISSN:1867-8610
Parent Title (English):Atmospheric measurement techniques discussions
Publisher:Copernicus
Place of publication:Katlenburg-Lindau [u.a.]
Document Type:Article
Language:English
Date of Publication (online):2016/12/09
Date of first Publication:2015/09/14
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2016/12/09
Volume:8
Page Number:48
First Page:9455
Last Page:9502
Note:
© Author(s) 2015. This work is distributed under the Creative Commons Attribution 3.0 License.
HeBIS-PPN:424759489
Institutes:Geowissenschaften / Geographie / Geowissenschaften
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 3.0