Organic Geochemistry
Contacts:
► Catherine Lorgeoux, technical manager
Tel. +33 (0)3 72 74 55 28
► Raymond Michels, scientific manager
Tel. +33 (0)3 72 74 55 61
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The objective is to characterise and analyse organic compounds in solid and liquid matrices, such as rocks, water or gas, in both geological and environmental contexts. The technical expertise and knowledge of organic matter that we have acquired have allowed us to be among the first to simulate the different steps in the formation of oil and gas.
We isolate the organic matter and then identify and quantify its molecular constituents. For this, we draw upon our unique expertise in a comprehensive array of anaytical techniques, including extraction, thermodesorption, pyrolysis, chromatography and mass spectrometry. The data obtained allow us to identify the sources of the organic products, characterise their mode of transfer as well as their interactions with the environment, and test for their inert or reactive nature.
A particular strength is our ability to adapt protocols and tools to the specific objectives of a scientific project. We work closely with clients in order to develop appropriate experimental and analytical strategies, employing innovative and original instrumental set-ups to achieve this.
The Organic Geochemistry Laboratory concerns itself with the analysis of solid (source rocks, soils or sediments), liquid (e.g., petroleum or water) and gas matrices. Samples are derived from in-situsampling as well as from experiments performed in the laboratory (e.g., oxidation, biodegradation and leaching) or at our experimental facility (e.g., artificial maturation using gold cells, reactions under temperature- and pressure-controlled conditions using autoclaves).
In order to study organic matter (OM) and its reactivity in different contexts, the laboratories are equipped with an array of instruments for preparing samples for analysis:
- Accelerated Solvent Extraction:
- Manual SPE (Solid Phase Extraction) for extraction from large volumes of water [A] and an ASPEC automated system (Gilson) [B] for the purification of extracts:
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These instruments are mostly used for extraction of OM, but can also, following carefully prepared experimental procedures, be used for investigating OM reactivity and the role of OM within simplified systems (for example, temporal variations, oxidation or leaching) for improving our understanding of real systems. The range of equipment available allows both qualitative and quantitative analysis of the organic compounds present in the matrices.
A number of instruments are available for characterisation of samples or extracts:
· UV/Vis spectrometer(Thermo Fisher Scientific);
- GC/FID-FPD (Agilent) - a gas chromatograph (GC) coupled with a flame ionization detector (FID) for hydrocarbon analysis and a flame photometric detector for detection of organic sulphur compounds;
[A] Chromatogram of a gas-oil obtained by FID
[B] Chromatogram of a sulphurized petrol obtained by FPD
- HPLC/DAD-Fluo-RID (Agilent) - a liquid chromotograph (HPLC) that functions with a Gel Permeation Chromatography (
[A] HPLC/
[B] HPLC/
- Additional instruments are available for molecular characterisation or quantification of target compounds:
GC/MS (Agilent and Shimadzu) - Three gas chromatographs (GC) coupled to a mass spectrometer (MS) with an electron-impact ionisation source and a quadripole analyser. One of the GC instruments is equipped with an
Chromatographic columns are selected according to the study requirements (for example, for the identification of non-polar, polar or sulphur compounds).
Gold-cell pyrolysis with n-octane in the presence of H2S: GC/MS identification of compounds
Injection of a soil extract derived from an industrial wasteland: quantification of Polycyclic Aromatic Compounds by GC/MS
Py/GC/MS: Flash pyrolysis (CDS) coupled with GC/MS (Agilent) to enable acquisition of molecular signatures with compound identification from solid samples: raw samples or residues after extraction from a solvent (‘non extractable’ residues).
The different signatures of aquatic (algae) and terrestrial (coal) organic matter, obtained by flash pyrolysis of non-extractable residues from the solvent.
HPLC/DAD-QTOF (Dionex/Bruker): liquid chromatograph (HPLC) coupled to a diode array detector (DAD) and quadripole mass spectrometer with time-of-flight (
The system enables us to analyse moderately- to highly-polar molecules and molecules with high molecular weights at high mass-resolution.
Mass spectrum obtained after direct infusion of an organic-metallic complex in a methanol/dichloromethane mixture in the electrospray source, operated in positive mode (
- When required, specific systems are developed by the team’s researchers and engineers to study particular research themes in more depth:
Thermodesorption/GC/TCD and thermodesorption/MDGC/FID-TCD
The first system (Agilent) enables analysis of light gases such as argon, nitrogen, carbon dioxide and hydrogen.
In the second system, the MultiDimension (Shimadzu) provides a resolution gain and enables simultaneous analysis of light gases (by catharometer) and C1 to C20 hydrocarbons (by flame ionization detector) in a single injection. Light gases are separated from hydrocarbons in a gas chromatography (GC) instrument and then sent to a second GC for finer separation and detection by catharometer (TCD).
The analysed gases are generated during reactions in controlled media conducted in ourexperimental facility. A thermodesorption oven enables work to be conducted at temperatures ranging from ambient temperature to 300°C and permits analysis of gases obtained from vessels (extracted from autoclaves) or from gold-cell piercing (artificial maturation).
Td/GC/MS-FID: Multi-shot pyrolyzer (Frontier Lab) coupled to a GC/MS-FID (Agilent)
This coupling allows the identification and quantification of organic compounds that are desorbed during a temperature program. Analyses can be carried out according to three modes:
- The EGA mode (Evolved Gas Analysis) mode: the sample is heated progressively in the thermodesorption oven and the desorbed compounds are analyzed by MS and FID (inert column without film, no chromatographic separation) with direct monitoring of the ion and signal profiles, respectively.
- The flash pyrolysis mode: the sample is pyrolyzed at a given temperature (usually c.a. 500 °C) for few seconds and analyzed by GC/MS-FID.
- The thermodesorption mode (Td) with cryo trap. The sample is heated according to a temperature program. The desorbed compounds are concentrated in the head column with a cryo trap and subsequently analyzed by GC/MS-FID.
This coupling allows the study of interactions between organic compounds and solid matrices (minerals, soils, sediments, source rock,...).
Analysis of a coking plant soil: mass loss curve (TG curve) and its derivative (
Chromatograms obtained at different temperatures and identification of molecules by mass spectrometry.
Autoclave/microGC: Equipped with a Rolsi® sampling valve, this system enables us to withdraw micro-samples of gas without disturbing the pressure in the autoclave. Changes can be monitored using very short time-steps. Equipped with three analytical compartments, two-minute analyses on the microGC (
[A] Autoclave/microGC system
[B] Exploded view of one of the µGC compartments
[C] Example chromatogram obtained in the A-compartment (molecular sieve).