coupled gas chromatography-molecular mass spectrometer-isotope ration mass spectrometer (GC-MS-IRMS)

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A coupled gas chromatography-molecular triple quadrupole mass spectrometer isotope ratio mass spectrometer (GC-MS/MS-IRMS) is requested for the new Geobiology working group, which enables the chromatographic separation of a substance mixture and subsequently the simultaneous mass spectrometric analysis of the organic molecules and their component-specific isotope ratios.This coupled GC-MS/MS-IRMS consists of a gas chromatography-mass spectrometry (GC-MS) unit that provides the separation, identification and quantification of biomarker molecules using temperature-controlled chromatography. The requested molecular mass spectrometer consists of a triple quadrupole analyser system, i.e. two quadrupole analysers with interposed collision cell (MS/MS) to cause collision-induced fragmentation of molecules to obtain essential structural information. GC-MS/MS further offers the possibility to filter out low concentrated substances from complex matrices and to detect them separately, which is not possible with a simple GC-MS. The coupling with the isotope ratio mass spectrometer (IRMS) with upstream oxidation or reduction reactors enables the determination of the carbon, nitrogen or hydrogen isotopy of the individual analytes within one measuring cycle.Until now, numerous analyses on different instruments were necessary and the laborious adjustment of the individual instrument parameters was required to assign the determined isotope values to the respective molecular peaks. This new class of instruments not only minimises the analytical effort, but also allows a much better analytical yield than the available individual instruments, which is a decisive advantage for the often small substance quantities of fossil samples. However, this innovative hybrid instrument allows high-resolution and material-efficient analyses with clear chromatogram peaks and simultaneous determinations of the carbon, nitrogen and hydrogen isotope ratios of the individual compounds. While the molecular structures of the organic molecules provide information about the associated organism groups and deposition conditions, the 13C, 15N, H/D isotopies of the analysed lipids provide information about food sources and metabolic pathways of the organisms. This additional information is essential for the determination of biosynthetic pathways and also decisive for the clear assignment of biomarkers, not only to a specific group of organisms, but also to the respective biogeochemical processes or the (palaeo-)environmental conditions. Within the Institute of Geology and Mineralogy, the working groups WG Geobiology (main user, instrument operator), WG Environmental Isotope Geochemistry and WG Quaternary Geology will use the applied GC-MS/MS-IRMS for palaeoreconstructions of fossil depositional environments with the help of biomarkers and their component-specific isotope fractionations.