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Geochemistry platform

The geochemical platform of the IDES laboratory is largely dedicated to the isotopical analysis of geological samples and isotopes being used as natural tracers. A more specific part is devoted to biominerals analysis. The platform constitutes a large fleet of spectrometers (mass spectrometers but also optical and flame spectrometers), chromatographs and various equipment for sample preparation (vacuum lines, extraction and preparation devices, lyophilisation etc). Chemistry rooms also allow the measurement of different physico-chemical data often needed to interpret the isotopic values (alkalinity, conductivity, pH etc).
The operation of the machines is provided by three Engineers (Marc Massault - responsible for the platform - Julius Nouet and Gael Monvoisin) and two Assistant Engineers (Claire Boukari and Aurélie Noret). Some very specific materials are also managed by the researchers. The geochemistry platform, the largest of the laboratory in terms of hardware and human resources, is spread over several floors and used by all the teams.

VG SIRA 10 mass spectrometer

This robust IR (Isotope-Ratio) Mass Spectrometer operates in dual inlet mode and allows to measure the d13C/12C, d18O/16O and d34S/32S in many compounds. The source may only analyse gas, therefore different preparation processes of the natural samples are required (combustion, acid attack, purification) to obtain a directly analysable gas (CO2 or SO2). The VG SIRA 10 is used to determine the d13C/12C of carbon in different materials (organic matter, dissolved carbon in water), and d13C/12C and d18O/16O in carbonates with an accuracy of respectively ± 0.1 ‰, ± 0.1 ‰ and ± 0.2 ‰. It can also measure d18O/16O and d34S/32S in sulfates (and d34S/32S in sulfides) with an accuracy of ± 1 ‰.

Contact : Aurélie Noret ; link to IDREau team

Finnigan Delta + mass spectrometer

This IRMS mass spectrometer is coupled to an equilibration bench which allows the analyses of delta18O/16O and deltaD/H in water samples. A gas (H2 for deltaD/H and CO2 for delta18O/16O) is brought into contact with the water sample and after a suitable equilibration time, the gas acquires the isotopic signature of the sample. It is then transferred to the source of the mass spectrometer and compared to a reference gas. This gives a measured isotopic signal and an external calibration is used to calculate the real isotopic signal of the water sample. The Finnigan Delta + mass spectrometer may analyse about 1,300 samples per year with an accuracy of ± 2 ‰ for deltaD/H et ± 0,2 ‰ for delta18O/16O.

Contact : Aurélie Noret ; link to IDREau team

LGR Laser Water Isotope Analyser OA ICOS DLT

This optical spectrometer measures the deltaD/H and delta18O/16O in water. The analysis is based on the Beer-Lambert law: a nano-sample of water is sprayed on the path of the infra-red laser beam and the interferences created are proportional to the isotopic ratios of the sample. The laser spectrometer can analyse samples as small as 100 µL. The accuracy of the measurements are ± 1 ‰ for deltaD/H and ± 0.2 ‰ for delta18O/16O. The capacity of this machine is more than 2000 samples per year.

Contact : Gaël Monvoisin ; link to IDREau team

Semi-automatic preparation line for 14C

This semi-automatic preparation line developed at IDES by Marc Massault allows the preparation of graphite targets for the analysis of 14C at the UMS LMC14 (ARTEMIS accelerator in Saclay). Any solid or liquid sample containing carbon can be analysed provided it is first converted into CO2 on a vacuum bench (by combustion of organic matter, acid attack, etc). On the graphitisation line, the CO2 reacts with hydrogen at 650°C to form graphite on an iron support. This line is controlled by Labview and can produce up to 24 samples per day and prepare samples smaller than a milligram. The IDES laboratory is the only unit outside the LMC14 accredited to provide graphite targets.

Contact : Marc Massault ; link to IDREau team

CFCs and SF6 analysis

This system consists of a GC-MS and a cryogenic separation line which allows us to concentrate and separate the elements dissolved in water before they are injected in gaseous form into the different devices. This setup allows for the analysis of SF6 and CFC 11, 12 and 113 (direct introduction by two injectors, separation on two capillary columns, two six-way valves, helium as carrier gas, detector ECD) and in the near future the elemental noble gases and nitrogen and oxygen (quadrupole mass spectrometer, primary and secondary pumping lines). For SF6, the sensitivity is better than the femtogram, it’s better than 0.5 picograms for CFCs. For rare gases, nitrogen and oxygen we aim to reach sensitivities of 100 ppb for He, Ne, and Kr; 100 ppm for Ar; 10 ppb for Xe and 10 ppm for and N2 and O2. To allow for an automated analytical protocol in the future (sample preparation on the line and analytical procedure), the devices are interfaced with National Instrument cards managed on Labview.

Contact : Florent Barbecot ; link to IDREau team

Dionex ICS-1000 ion chromatography

The ICS-1000 operates in ion exchange mode: into the chromatographic column, the different ions of a sample migrate at different speeds dependent on their affinity for the exchange sites. At the column’s outlet, a cell measures the conductance of the solution and produces a signal dependent on the chemical or physical properties of the analyte. By comparing the results with those of a standard solution, we can identify and quantify the ions in the sample.

Contact : Cécile Quantin ; link to IDREau team

Atomic Absorption Spectrometer, flame or furnace mode: AAS 240 FS Varian

Using flame mode, the atomic absorption spectrometry allows the making of measurements of major, minor or even trace elements in concentration ranges from 0.05 to 15 mg / L depending on the elements. Aqueous solutions are sampled with an autosampler coupled to an automatic diluter, which also enables the preparation of automatic calibration scales, and the adding of matrix modifiers. Samples are then sprayed into a flame at high temperature. A mono or multi-element hollow cathode lamp, emitting in the characteristic wavelength of the analysed elements, allows a photocell to dose each element’s radiation. The absorption signal is proportional to the concentration of the element.
In furnace mode, the graphite furnace enclosure is small and filled with inert gas, it permits the measurement of trace elements at concentrations of a few µg / L.
Applications developed in our laboratory enables measuring the following elements by either flame or graphite furnace mode : Na, K, Ca, Mg, Mn, Fe, Cu, Ni, Pb, Cr, Co, Zn and Al. These data are used to study soils, characterize liquid samples (soil solution, groundwater, surface water) and determine the behavior of trace metals in soils.

Contact : Gaël Monvoisin ; link to IDREau team

Biological samples analysis

A number of gas and liquid chromatographs is dedicated specifically to the samples of the "Biocrystallisation, Paleoclimate and Sediment Dynamics" team. These machines allow us to analyze molecular masses, amino acids, ions etc. This part of the platform also includes analytical and preparative electrophoresis in 1D and 2D.
Contact : Julius Nouet ; link to Biocristallisation, Paléoclimats et Dynamiques Sédimentaire team; ;

Extraction and analysis of organic matter

A varity of machines are dedicated to the analysis of organic matter for the study of biominerals (Freeze-drying, Speed-Vac, UV-vis spectroscopy, FT-IR spectrometry, fluorometry etc).

Contact : Julius Nouet ; link to Biocristallisation, Paléoclimats et Dynamiques Sédimentaire team; ;

Rare gases analysis

  • Helium extraction line for (U-Th)/He datation and experiments of helium diffusion.

This facility allows the automatic analysis of helium concentrations in various minerals via LabVIEW software. It is composed of a helium extraction device by laser heating (Photo B) or lamp heating (Photo E), and a purification part, then the analysis is done using the Prisma quadrupole mass spectrometer. Up to 25 samples of apatites packed in platinum capsules can be placed in the carrier (Photo C) and samples are brought to the laser by an automated XY system. The capsules are heated one by one at a suitable temperature between 950 and 1250°C, this temperature is controlled via images taken by the camera and can be regulated (Photo D). In addition, helium can be extracted at a lower temperature (30 to 700°C) using a heating lamp (Photo E). The sample temperature is then measured directly using a thermocouple, and regulated. Known standards (a 3He cylinder of known concentration, and another of known 4He/3He ratio), allows the conversion of the electrical signal measured by the mass spectrometer into a number of atoms.

  • VG5400 Line: Analysis of concentrations and isotopic ratios of He, Ne and Ar.

This facility allows the analysis of concentrations and isotopic ratios of He, Ne and Ar for various types of samples (solid, water) and via different methods of extraction (crushing, heating, steaming - Photo A, B and D). For the fluids, the sample of water or gas is expanded in a 1 liter flask where there is a high vacuum of about 10-6 torr where the fluids are completely vaporised. A small known volume of the obtained gas is then relaxed in a new container. This gas is then purified so that gases other than noble gases are decomposed. After these purifications, a volume of that sample is introduced into the main line, where it undergoes a third purification. Finally, a separation of the different noble gases is achieved by means of active charcoal traps cooled with liquid nitrogen or liquid helium. For other extraction systems (by crushing or heating) and purifications, the gas may be analysed by the Prisma quadrupole mass spectrometer (Photo C) or by the VG5400 magnetic sector mass spectrometer (Photo E). The VG5400 used underwent a home-made rejuvenation (collectors, source, electronics of the solenoid and LabVIEW software were changed). Two gas bottles (He and air), allow the calibration of He, Ne and Ar signals.

Contact : Cécile Gautheron ;
link to team

K/Ar and Ar/Ar datation mass spectrometers

The following devices are primarily used by the team "Geochonology, Dynamics of volcanic systems" for dating geological samples by the K/Ar and Ar/Ar methods. They were all developed by the team itself.

Instruments used for Ar/Ar datation

  • A 180° pentacollector mass spectrometer with extraction line either by HF furnace or by laser melting (YAG laser).

  • A 120° high sensitivity mass spectrometer with its CO2 laser extraction line.

Instruments used for K/Ar datation

  • A 180° mass spectrometer with HF furnace extraction line.
  • A second 180° mass spectrometer with HF furnace or YAG laser extraction line.
  • A quadrupole with its laser extraction line.
  • A Varian Sprectr AA-200 flame spectrometer.

Contact : Claire Boukari ; link to Géochronologie, Dynamique des systèmes volcaniques team