Darmstadt 2008 – scientific programme
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K: Fachverband Kurzzeitphysik
K 4: VUV - EUV Lichtquellen und deren Anwendungen
K 4.1: Invited Talk
Tuesday, March 11, 2008, 14:00–14:30, 2D
Electron beam pumped rare gas excimer lamps for soft photo ionization of organic compounds in mass spectrometry: Application for on-line monitoring, gas chromatography and thermogravimetry — •Ralf Zimmermann1,2, Werner Welthagen1,2, Thomas Gröger1,2, Robert Geißler1,2, Mohamed Saraji1,2, Marc Gonin3, Katrin Fuhrer3, Thorsten Streibel1,2, and Martin Sklorz1,2 — 1Analytical Chemistry, Institute of Physics, University of Augsburg, D-86159 Augsburg, Germany — 2Institute of Ecological Chemistry, GSF - National Research Centre for Environment and Health — 3TOWERK AG, CH-3602-Thun, Switzerland
Single photon ionization (SPI) with novel intense rare gas excimer VUV-light sources (electron beam-pumped rare gas excimer lamps - EBEL) recently was used for efficient on-line detection of organic molecules in a quadrupole mass spectrometer (QMS). In this work, an ultra compact orthogonal acceleration time-of-flight mass spectrometer system (oaTOFMS) was coupled to the novel EBEL-based photo ionisation method. The rugged and very compact SPI-oaTOFMS instrument was characterised with test gas mixtures and used for first on-line measurement applications, including the rapid speciation of complex liquid fossil fuel samples (gasoline, diesel) by headspace sampling as well as time-resolved measurements of tobacco smoke (single puff-resolved). Detection limits in the low ppb region were achieved with the used EBEL prototype. In addition to direct on-line analysis the SPI-oa-TOFMS technology has also been employed in hyphenated analytical instrumental concepts. This includes the coupling with gas chromatography (GC) as well as evolved gas analysis in micro-thermogravimetry (TG). In the conventional GC-MS coupling, electron impact ionisation (EI) is applied and molecules are identified by their "fragment-spectrum". Although mass spectrometry in principle is a separation technique, it is thus normally used as "fragment-spectrometric" technique in GC-MS. However, if soft ionisation techniques -such as SPI- are applied, the "mass separation" character of MS is emphasized, which in fact resembles a conventional GC boiling point separation. This allows the use of the GC-SPI-oaTOFMS approach as a novel, very efficient comprehensive two-dimensional separation method.