Using pyrolysis-GCxGC-TOFMS to analyze organic carbon in carbonaceous chondrites gives a massive increase in both sensitivity and structural information from samples when compared to traditional Py-GC-MS

Gilmour, I.

Morgan, G. H.

Pearson, V. K.

Perkins, R.

Pillinger, C. T.

Turner, D.

Watson, J. S.

English

Open Research Online

Open Research OnlineThe Open University’s repository of research publicationsand other research outputsPyrolysis-GCGC-TOFMS to characterize carbonaceouschondritesConference or Workshop ItemHow to cite:Watson, J. S.; Pearson, V. K.; Gilmour, I.; Pillinger, C. T.; Turner, D.; Perkins, R. and Morgan, G. H. (2005).Pyrolysis-GCGC-TOFMS to characterize carbonaceous chondrites. In: 36th Lunar and Planetary Science Conference,14-18 Mar 2005, Houston, Texas, USA.For guidance on citations see FAQs.c© [not recorded]Version: [not recorded]Link(s) to article on publisher’s website:http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1842.pdfCopyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukPYROLYSIS-GC×GC-TOFMS TO CHARACTERIZE CARBONACEOUS CHONDRITES.  J. S. Watson1, V. K. Pearson1, I. Gilmour1, C. T. Pillinger1, D. Turner2, R. Perkins2, G. H. Morgan1, 1Planetary and Space Sciences Research Institute, Open University, Walton Hall, Milton Keynes, MK7 6AA, UK (j.watson@open.ac.uk or g.h.morgan@open.ac.uk),  2Anatune Ltd, Broadway House, 149-151 St Neots Road, Hardwick, Cambridge, CB3 7Q, UK.   Introduction:  The carbonaceous chondrite mete-orites contain up to 5 % indigenous extraterrestrial organic material, including many organic species that are important biological precursors. However, due to its high molecular weight nature, the majority of this organic phase can only be analyzed following thermal decomposition in order to elucidate small molecular weight fragments that are amenable to gas chromatog-raphy.  Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) has been used in the analysis of materials such as carbonaceous chondrites [1,2], however tradi-tional systems can be easily overwhelmed by the com-plexity of the sample and a great deal of information can be lost by the inability to resolve these unresolved complex mixtures (UCM). Recent advances in instru-ment design have resulted in a major increase in sensi-tivity and analytical resolution of pyrolysis-based in-struments. Fig 1: Total ion chromatogram of Murchison car-bonaceous chondrite using traditional Py-GC-MS. X = xylenes, BN = benzonitrile, N= naphthalene, BT = benzothiophene, MN = methylnaphthalenes, BP = bi-phenyl. We have used the Pegasus 4D GC×GC-Time of Flight Mass Spectrometry system from Leco to ana-lyze the organic material in five carbonaceous chon-drites: Murchison, Orgueil, Renazzo, Cold Bokkeveld and Tagish Lake.   Results:  Figure 2 displays the total ion chroma-tograms (TIC) from Murchison obtained by analyzing 1% of the amount of whole rock sample normally re-quired for traditional Py-GC-MS (Figure 1). When compared to traditional techniques this new method of analyzing extraterrestrial organic material can signifi-cantly increase the resolution of the components pre-sent and elucidate significantly more compounds than have previously been observed. Figure 3 shows a partial mass chromatogram (m/z 91) from Murchison demonstrating the ability of the Py-GC×GC-TOFMS system to separate a number of different isomers. Isomers of alkylbenzenes up to C5 were identified, which are rarely identified by tradi-tional techniques. This system therefore significantly improves the structural information obtainable about the organic carbon present in carbonaceous chondrites. Fig 2: Total ion chromatogram of Murchison car-bonaceous chondrite using Py-GC×GC-TOFMS.  Discussion:  The main advantages of Py-GC×GC-TOFMS include:   i) The increased sensitivity of the mass spectrome-ter, over the whole mass range, when compared to the more conventional quadrupole mass spectrometer. ii) The 2D gas chromatograph is able to separate compounds that co-elute on a standard gas chromato-graph system. Separation of analytes by volatility and Lunar and Planetary Science XXXVI (2005) 1842.pdfpolarity enables traditionally unresolved complex mix-tures (UCM) to be examined in detail, and vastly in-creases the number of compounds identified. iii) Greatly increased signal to noise ratio, due to compounds being separated from the column bleed of the first column on the second GC column and a Spec-tral Generation Rate of up to 500 spectra/sec.   Figure 3: Partially reconstructed mass chroma-togram (m/z 91) displaying the alkylbenzenes released upon pyrolysis of the Murchison meteorite displayed in 2D and 3D.  Conclusion:  The discussed advantages of the GC×GC-TOFMS system over a standard quadrupole GC-MS system mean that a fraction (approximately two orders of magnitude less) of sample can be used, but also with a massive increase in the information gained from the sample. This increase in resolving power and sensitivity provides us with the opportunity to analyze samples that have in the past been unattain-able, such as interplanetary dust particles (IDPs), mi-crometeorites and the ability to gain information on the organic constituents from sample return missions. Other areas of astrobiology that could benefit from this technique include the detection of biomarkers and me-tabolites in extremophiles. References:  [1] Gilmour, I. (2004) in Meteorites, Comets and Planets (ed. Davies, A. M.), Elsevier, 269-289. [2] Watson J. S., et al. (2004) International Jour-nal of Astrobiology, 3, 107-116. Lunar and Planetary Science XXXVI (2005) 1842.pdf

Pyrolysis-GC×GC-TOFMS to characterize carbonaceous chondrites

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Pyrolysis-GC×GC-TOFMS to characterize carbonaceous chondrites

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