Abstract
What follows is a method applicable generically to the analysis of low levels of organic matter that is embedded in either loose fine-grained or solid geological material. Initially, the range of organic compounds that could be detected in a geological sample using conventional pyrolysis chromatography/mass spectrometry was compared to the range that was detected using thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry (THM-GC/MS). This method was used to validate the synthetic components fitted to X-ray photoelectron spectroscopy (XPS) carbon spectra of the sample. Reciprocally, XPS analysis was able to identify the constituent carbon-carbon, carbon-oxygen and carbon-nitrogen bonds of the functional groups in the compounds identified by THM-GC/MS. The two independently derived outputs from the THM-GC/MS and the XPS techniques mutually validated the identification of organic compounds in our geological samples.We describe in detail the improvements to:•The preparation of geological samples for analysis by XPS.•Measurements of organic material in geological samples using GC/MS.•The use of THM-GC/MS and XPS data used together to characterise low levels of organic material in geological samples.
Highlights
This analysis was conducted using a combination of thermal hydrolysis and methylation (THM) coupled gas chromatography/mass spectrometry (GC/MS), and X-ray photoelectron spectroscopy (XPS)
The number and positions of the synthetic components were informed by the data that was obtained from the THM-GC/MS analysis
These compounds are susceptible to thermal decomposition [15], and fewer (7.8%) of these compounds were detected in the THM-GC/MS conducted at 610 C and were absent in the THM-GC/ MS conducted at 1000 C
Summary
Graham Purvisa,*, Naoko Sanob, Cees van der Landa, Anders Barlowc, Elisa Lopez-Capela, Peter Cumpsond, James Hoode, Jake Sheriffe, Neil Graya a Earth, Ocean & Planetary Science Research, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK b Ionoptika Ltd., Eastleigh, Hampshire, UK c Materials Characterisation and Fabrication Platform (MCFP), Department of Chemical Engineering, The University of Melbourne, Melbourne, Victoria, Australia d Mark Wainwright Analytical Centre, University of New South Wales, Sydney, New South Wales, Australia e National ESCA and XPS Users’ Service (NEXUS), Newcastle University, Newcastle upon Tyne, UK
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