Organic geochemistry

Our Organic Geochemistry Facility provides capability to develop scientific understanding of organic compounds in soils, sediments and waters. Investigations cover four main themes.

Pollution studies and environmental forensics

  • quantification of persistent organic pollutants (POPs) in soils, sediments and waters including:
    • total non-volatile hydrocarbons (saturate/aromatic and heterocyclic compound classes) by thin layer chromatography and flame ionisation detection (TLC-FID, Iatroscan)
    • total petroleum hydrocarbons (TPH) by gas chromatography flame ionisation detection (GC-FID)
    • 15 of the 16 US Environmental Protection Agency priority pollutant polycyclic aromatic hydrocarbons (PAH) by high pressure liquid chromatography (HPLC) with fluorescence detection
    • polychlorinated biphenyls (PCB) reported as individual International Committee for the Exploration of the Sea or ICES 7 PCB and Σtri, tetra, hepta, hexa and hepta homologues
    • ΣPCB congeners by gas chromatography/mass spectrometry (GC/MS). (Values can be normalised to total organic carbon (TOC) to enable direct sample comparison)
  • analysis of volatile organic compounds such as BTEX (benzene, toluene, ethylbenzene, and xylene) and TCE (trichloroethylene) by headspace GC/MS
  • analysis of pesticides such as mecoprop, atrazine and diuron
  • measurement of organo-metallic species such as tributyl-tins (TBT)
  • analysis of xenoestrogens
  • quantification of explosives (formulations HMX, RDX and TNT) in sediments by HPLC
  • quantification of sewage sterols in environmental samples by GC/MS
Organic compounds present in sediments and waters are identified using Varian 1200L GC/MS/MS system. Macromolecules are routinely analysed by linking Chemical Data Systems pyrolyser (AS2500) to the GC/MS/MS
Iatroscan (TLC-FID) a screening tool quantifying saturated and aromatic hydrocarbon fractions in soils and sediments

Terrestrial and marine palaeoenvironmental analysis

  • application of analytical pyrolysis combined with gas chromatography-mass-spectrometry (Py-GC/MS), chemolysis-GC/MS and infrared spectroscopy (FTIR), to characterise structural polymers and macromolecules (polysaccharides, lignin, suberin and tannin) and geomacromolecules (kerogens and coal). Applications include palaeoenvironment reconstruction, determination of biotic and abiotic alteration, and investigation of biochemical evolution
  • quantification of black carbon in soils and sediments by chemothermo/oxidation
  • isolation of dissolved organic carbon (DOC) in groundwaters by tangential-flow ultrafiltration (TFU)

Climate change

  • Analysis of fossil biological molecules as biomarkers for the estimation of palaeotemperature and palaeoclimate. Solvent-soluble organic matter in sediment is removed by by accelerated solvent extraction (ASE) fractionated by column chromatography and analysed by GC/MS (in either full scan or selected ion-monitoring mode). Investigated biomarkers include
    • n-alkanes, n-alkanols, carboxylic acids, sterols (palaeoecology and atmospheric transport)
    • highly branched isoprenoids (palaeosalinity)
    • alkenones for the UK37 and UḰ37 sea-surface temperature proxy
Specialist research instrumentation for application in investigations of marine and estuarine pollution, climate change, energy and past land-use and development
Collecting sediment cores for geochemical studies of past sea-level rise in the Holocene

Hydrocarbon exploration and reservoir studies

  • oil-source-rock correlations, oil-oil correlations and reservoir studies using TOC and Iatroscan screening for saturate, aromatic and polar (NSO) fractions
  • quantification of saturate fraction using GC-FID
  • evaluation of n-alkane envelop, CPI, pristine/n-C17 ratio, Pr+Ph/n-alkanes to indicate maturation, migration, biodegradation
  • detailed investigation of oil chemistry by analysis of the saturate fraction by GC/MS (SIM mode) for specific biomarkers such as steranes, triterpanes and a variety of other compound classes

Contact

Please contact Dr Chris Vane for further information