Flame or Graphite Furnace Atomic Absorption Spectrometer to analyze cation concentrations (Al, As, Ba, Ca, Cr, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Pt, Sb, Sn, Sr, Zn)

Description of the instrument

The Atomic Absorption Spectrometer (Agilent Technologies AAS 240 FS and GTA 120) can measure the concentrations of many elements. Depending on the concentrations of the solutions, it can be used in flame mode or in graphite furnace mode. It is equipped with automatic diluters (flame/oven) and autosamplers (flame/oven).

Principle of analysis

A liquid sample is injected as a mist into a flame (in flame mode) or a drop is placed in a graphite furnace (in graphite furnace mode). The heat vaporizes the elements contained in the sample and excites their atoms. These disrupt a light signal by reducing its intensity (absorption) or by emitting photons (emission). The light emitted by a hollow cathode lamp(s) or by the electrons of the excited atoms is sent via a set of mirrors and a crystal lattice to a detector which performs an optical measurement of the signal compared to a signal of undisturbed reference. The difference in light intensity is proportional to the concentration of the element in the solution. Calibration is done by injecting a standard solution to obtain the appropriate range. See principle of measurement here: http://spin.mines-stetienne.fr/sites/default/files/specatom.pdf

Analyzes carried out on the instrument

• Major cations (Ca, Mg, Na and K) between 0.05 and 100 ppm in flame with an accuracy of +/- 5%;
• Metals (Al, As, Ba, Cr, Co, Cu, Fe, Li, Mn, Mo, Ni, Pb, Pt, Sb, Sn, Sr, Zn) between 0.01 and 1000 ppm in flame depending on the elements and a few tens of ppt to a few tens of ppb in graphite furnace mode for some elements with an accuracy of +/- 5%;
• Only liquid solutions (filtered and acidified) are analyzed but it is possible to measure solutions of acid attack on rocks, sediments or other solid samples.

Contacts

Gaël Monvoisin : + 33 (0)1.69.15.71.74 / gael.monvoisin@universite-paris-saclay.fr

Fundings

CNRS – INSU / University Paris-Sud : AAS flame Year 2010 – AAS graphite furnace Year 2012

MC-ICPMS Neptune^Plus Thermofisher Scientific

MC-ICPMS Neptune Plus (2010)		Laser ESI –NWR 193 nm (2011)

Characteristics of Instrumentation:

The MC-ICPMS Neptune^Plus is a mass spectrometer (MS) with a source of Argon plasma (ICP), a dual focusing (electrostatic field + magnetic field) and a multi-collection (MC). This mass spectrometer allows the precise measurement of stable, radiogenic or radioactive isotopes for many chemical elements of the Periodic Table in natural archives (waters, carbonates, apatites, sediments, soils, rocks, etc.). The high ionization efficiency of the Plasma source gives it a great sensitivity. Its dual focusing ensures good transmission of the ion beam and offers us the ability to work at low, medium or high resolution (suppression of some isobaric interferences). Finally, the high stability of multi-collection provides an excellent analytical accuracy on isotopic ratios (external reproducibility ranging from a few tens of ppm to sub- ‰). Another advantage is that the plasma source, opened to the atmosphere, allows us to introduce and analyze samples in liquid form after chemistry (micro-nebulizers, desolvating systems) or directly on solids (Ablation Laser coupling). Main fields of application are geochronology (U-Th dating), marine geochemistry and paleoceanography (Pa, Th, U, Ra, Nd isotopes), carbon cycle in ocean and the impact of ocean acidification (B, Th, Si isotopes), isotopic characterization of volcanic or sedimentary rocks or some developments in archeology (Nd, Sr, Pb or even Cu, Zn, Fe Isotopes).

Principle of Measurement:

In solution, the sample is aspirated and injected by a spray nebulizer into a "Plasma" source of argon at 6000-8000°K and atmospheric pressure. At this high temperature, the elements are ionized. Transferred by an interface (sampler and skimmer cones), the ions are accelerated under primary and then secondary vacuum to form an ion beam with a final energy of up to 10 keV. The beam is filtered in energy (electrostatic sector), then in mass (magnetic sector) according to the ratio m/z. The isotopes are detected by a multi-collector system with 15 detectors (9 Faraday cages, 1 SEM and 5 CDD). The isotopes and ratios are then measured and calculated at high precision simultaneously on several detectors. Obtained external reproducibilities are of a few tens of ppm for the isotopes of Sr, Nd, from 0.05 to a few 0.1 ‰ for Li, B isotopes or of the order of 1 ‰ for systems with low isotopic ratios (U and Th isotopes). The central cage ion beam can switch over to the central ion counter (SEM) if the signal is too low, making it possible, for example, to measure the isotopes ²³⁰Th and ²³⁴U, isotopes essential for U-Th dating. For few isotopic systems (Si, Fe or more generally transition metals), measurements are carried out in medium or high resolution in order to separate the analyzed isotopes from potential isobaric interferences. In such configuration, signal intensity is decreased but resolving power can be increased by 10-fold.

MC-ICPMS isotopic measurements are relative and require laboratory or international standards or reference materials whose isotopic values ​​are known and / or certified (NIST). The “bracketing” protocol is generally used to characterize precisely the isotopic composition of a studied element and to take into account the instrumental drifts. It is possible to introduce into the plasma source solutions previously purified in a clean room but also a flow of helium gas which entails aerosols. Thus, isotopic measurements of some elements such as Sr, B or U in carbonates are performed after coupling with the laser ablation system Excimer NWR193 nm.

Others information

• Nebulizers PFA 20, 50 ou 100 µL/min & micro-cyclonic chamber (solutions)
  
• Desolvating inlet system APEX Omega and Omega HF & ARIDUS II + QuickWash (2 to 10 -fold sensitivity increase, solutions)
  
• Jet-Interface installed in 2014 (reinforced sensitivity: from 2 to 5-fold, solutions)
  
• Ablation laser Excimer ESI – NWR 193 nm (in-situ analysis, aerosols from solid materials)

Isotopic measurements performed by MC-ICPMS:

Solutions (after chemistry)

• U, Th, Pa, Ra: U-series Geochronology, marine or continental Geochemistry ;
• Sr, Nd and recently Pb for various natural materials: source determination, erosion, ocean circulation and dynamics, archeological studies ;
• B and Li for carbonates or waters: paleo-pH and ocean acidification (carbon cycle), marine biogeochemistry ;
• Other systems: Si, Fe, Cu, Zn, etc.

Solid matrix per Ablation laser (development in progress)

• B (δ¹¹B), of Sr (⁸⁷Sr/⁸⁶Sr) and U (δ²³⁴U) in carbonates or silicates.

Contacts:

Instrumental responsible

Arnaud Dapoigny arnaud.dapoigny[a]lsce.ipsl.fr 01 69 08 04 70

Main Scientist responsible

Dr Eric Douville (B, Li, Sr) eric.douville[a]lsce.ipsl.fr 01 69 08 22 57

Other GEOPS-LSCE scientists involved:

Dr Christophe Colin (Nd, Sr), Dr Edwige Pons-Branchu (U, Th, Ra, Sr, Pb), Claire Rollion-Bard & François Thil (Laser), William Gray (B), Damien Guinoiseau (Pb).

Inductively Coupled Plasma – Quadrupole Mass Spectrometer - ICP-QMS X-series^II CCT

Characteristics of Instrumentation:

The Inductively Coupled Plasma – Quadrupole Mass Spectrometer (ICP-QMS) X-series II CCT Thermo Fisher Scientific is dedicated to quantitative multi-element analysis. This instrument allows rapid (~ minute), precise (~ percent) and quasi-simultaneous determination of the content of many chemical elements of the Periodic Table from the majors to those present in trace amounts in natural samples (freshwater, seawater, plants, soils, carbonates, apatites, rocks, etc.) or for any other type of materials or solutions. In its basic configuration, this mass spectrometer offers detection limits lower than μg / L (ppb) for many elements in solution and can reach several 100 pg / L (ppq) for heavy elements such as Rare Earth Elements or Uranium. Two options improve its performance: i- the CCT collision cell eliminates polyatomic interferences, typically for elementary analysis with atomic mass between 40 and 80 (transition metals, metalloids such as As, Se) ; ii- an additional pumping called “option S” at the interface lowering the detection limit for some heavy elements (uranium) to a few pg / L.

Three major application domains are currently being developed at the LSCE: i- elementary or isotopic (Pb) characterization of samples dissolved in solution to trace erosion processes, study of particle mobility as well as determine their origins, and quantitatively monitor the dissemination of some heavy or toxic metals in the environment, particularly in urban environments ; ii- elementary characterization of marine or continental carbonates/apatite archives (corals, foraminifera, speleothems, teeth, etc.) for paleoceanography, climatology or archeological studies (marine geochemistry, ocean temperature, carbon cycle and ocean acidification, precipitation, etc.) ; and iii- U-series Geochronology and U-Th dating of carbonates (corals) or apatites (teeth).

Principle of Measurement:

The principle is based on dissociation of molecules, atomization and ionization of the elements present in a solution and injected into a "Plasma" source of argon at 6000-8000 °K and atmospheric pressure. After the formation of an ion beam via the interface (sampler and skimmer cones) during a progressive transition to a secondary vacuum, a Quadrupole separates the isotopes or ions at low resolution according the m/z ratio. The ions/isotopes are then detected by a discrete-dynode electron multiplier. The precise quantification of the contents of major and / or trace elements is obtained after calibration of the instrumentation (standard solutions known or certified). Depending on the matrix or nature of the samples analyzed, the elements studied and the degree of precision sought, different calibration methods are used (standard calibration curves, standard addition or matrix recomposition methods, “bracketing” approach).

Other informations

• Nebulizers : PFA 20, 50 or 100 µL/min ; quartz 1 mL/mn (solutions);
• Quartz micro-cyclonic spray chamber or conic chamber with impact bead (solutions);
• Desolvating systems APEX HF (2 à 10-fold more sensitive, solutions) ;
• Ablation laser Excimer ESI – NWR 193 nm (in-situ analysis, aerosols from solid materials).

Measurements performed by ICP-QMS:

• Quantification of major and/or trace elements in waters, soils, rocks, carbonates (erosion / transfer of particles) ;

• Relative measurement of Pb isotopes (source tracing) ;

• Quantification of majors (Sr/Ca, Mg/Ca) and trace elements (Li/Mg; B/Ca; Ba/Ca, U/Ca, REE, etc.) present in carbonates like corals or speleothems (paleoceanography / climatology / carbon cycle) ;

• Quantification of rare earths and other elements present as ultra-traces in seawater or sediments (characterization of materials or processes) ;

• Relative measurement of U and Th isotopes for U-Th dating of corals, speleothems, teeth.

Contacts:

Delphine Thomas : delphine.thomas[a]lsce.ipsl.fr    01 69 08 33 77

Sophie Ayrault : sophie.ayrault[a]lsce.ipsl.fr   01 69 08 40 71

Eric Douville : eric.douville[a]lsce.ipsl.fr       01 69 08 22 57

Flash EA 1112 Series                                                 Delta Plus XP

Characteristics of Instrumentation:

Isotope Ratio Mass Spectrometer (IRMS) Delta Plus XP (ThermoFinnigan), installed at LSCE in 2001, coupled to an Elemental Analyzer Flash EA 1112 Series installed in 2008. This spectrometer is a Continuous Flow type spectrometer. It is dedicated to the analysis of organic matter contained in different types of samples (sediments, bones, tissues, particles in suspension, etc.). The measurement accuracy of carbon isotopes is about 0.05 ‰. The amount of carbon required for a measurement is from 20 to 40 μg for isotopic measurements and an amount of 10 to 15 mg of samples is required for elemental analysis.

Principle of Measurement:

http://en.wikipedia.org/wiki/Isotope-ratio_mass_spectrometry

Measurements performed by instrumentation:

Carbon and nitrogen elementary quantification and carbon isotope (δ¹³C) analysis of organic matter. Developing in progress of isotopic measurements of nitrogen.

Contacts:

Caroline Gauthier : caroline.gauthier[a]lsce.ipsl.fr

Christine Hatté : christine.hatte[a]lsce.ipsl.fr

Jérémy Jacob : jeremy.jacob[a]lsce.ipsl.fr

View of part of the LSCE gamma detectors

Description of instrument:

Gamma spectrometry is a direct and non-destructive measurement technique.

Soil or sediment samples should simply be dried in an oven, crushed and sieved. The samples are then packaged in standardized boxes and placed on a gamma detector.

At the LSCE, the detectors are crystals of hyperpure germanium (N or P type) cooled with liquid nitrogen. The gamma photons produced by the disintegration of the radioisotopes present in the sample arrive on the germanium crystal and are converted into electrical signals. These signals are amplified, identified by an encoder and then stored in a multichannel analyzer that classifies and totalizes the number of photons emitted according to their energy.
A gamma spectrum is obtained in which each energy line is characteristic of a radioisotope and the area of each peak is proportional to the amount of these radioisotopes in the sample.

In order to protect the detectors against the ambient radioactivity generated in particular by cosmic rays and atmospheric radon, these are installed in the basements of the laboratory (L'Orme des Merisiers site - 6 detectors in service) or even under 1700 meters of rock in the Alps (site of Modane - 3 detectors operated by the LSCE).

Moreover, They are protected by lead, iron and copper shielding that reaches a thickness of 15 to 20 cm.

Principle of analysis:

Radioactive isotopes (or radioisotopes) are unstable elements whose radioactivity decreases over time. Each radioisotope is characterized by a half-life period which is a constant and which corresponds to the time required for half of the present atoms to disintegrate. The use of radioactive markers in the study of soil erosion processes dates back to the 1960s, with the advent of the nuclear age. The soil has a natural radioactivity due to the presence of certain chemical elements (typically uranium, thorium and potassium). It is also subjected to the flow of radioactive isotopes produced or released in the upper atmosphere and which eventually fall back to the ground. Some of these radioisotopes are natural (such as beryllium-7) and are called "cosmogenic". Others are said to be artificial (such as cesium-137) because they have been introduced into the atmosphere as a result of nuclear tests and incidents that affected nuclear power plants in the second half of the 20th century.

Of all the radioactive isotopes present in the environment, there are only a few that can be used as "markers" for displacements of soil particles. These radioisotopes must have a high chemical affinity for soil particles and must have a relevant half-life for studying the studied processes. Radioisotopes can emit different types of radiation (alpha, beta or gamma). Gamma emitters are generally preferred, for their ease of detection and analysis. Indeed, no prior chemical separation of the soil samples is required.

Analyzes carried out:

• The natural radioisotopes of the U-238 chain (Th-234 / Ra-226) including Pb-210 and Th-232 (Th-228 / Ra-228) and K-40, Be-7
• Artificial radioisotopes such as Cs-137; Am-241, Co-60

Matrices: dry solids (oven drying or lyophilization) and sieved to 2 mm.

Contacts:

Irène Lefèvre : irene.lefevre[a]lsce.ipsl.fr

Olivier Evrard : olivier.evrard[a]lsce.ipsl.fr

Cryogenic magnetometer with helium equipped with high resolution pick-up coils designed for measurements on u-channel type samples (2G Enterprises)

Instrument description:

Helium-free cryogenic magnetometer dedicated to the high resolution (4.5 cm) measurement of Isothermal Remanent Magnetization (IRM) on continuous series (maximum square section of 22 mm, maximum length of 1.5 m). Three alternating field (AF) coils are installed in line for stepwise demagnetization, as well as one solenoid for ARM acquisition. The system is placed in the µmetal shielded room.

Principle of the analysis:

The remanent magnetization is measured along the 3 axes X, Y, Z with high resolution pick-up coils. The magnetizations can be demagnetized along the three axes by alternating field up to 100 mT. Stepwise acquisition of IRM can also be performed as well as its stepwise AF demagnetization. The entire procedure is controlled using a dedicated software.

Analyses performed with the instrument:

• Measurement of isothermal remanent magnetizations (IRM) on continuous series

• Stepwise AF demagnetization

Contact:

Gwenaël Hervé : 01.69.08.02.48 / gwenael.herve[a]lsce.ipsl.fr

Instrument description:

Cryogenic magnetometer dedicated to high resolution (4.5 cm) measurement of remanent magnetizations (Natural Remanent Magnetization (NRM), Anhysteretic Remanent Magnetization (ARM), Isothermal Remanent Magnetization (IRM)) on continuous series (maximum square section of 22 mm, maximum length of 1.5 m). Three alternating field (AF) coils are installed in line for stepwise demagnetization and a long solenoid for the acquisition of high field IRM (up to 1T). The magnetometer is placed within the µmetal shielded room.

Principle of the analysis:

The remanent magnetization is measured along the 3 axes X, Y, Z with high resolution pick-up coils. The magnetization can be demagnetized along the three axes by alternating field up to 100 mT. Stepwise acquisition of IRM can also be performed as well as the back-field acquisition (S-ratio, HIRM). The entire procedure is controlled using a dedicated software.

Analyses performed with the instrument:

• Measurement of all remanent magnetizations (NRM, ARM, IRM) on continuous series
• Stepwise AF demagnetization
• Acquisition of high field IRM.

Contact:

Gwenaël Hervé : 01.69.08.02.48 / gwenael.herve[a]lsce.ipsl.fr

Instrument description:

Cryogenic magnetometer equiped with three high homogeneity pick-up coils. The magnetometer is placed within the µmetal shielded room.

Principle of the analysis:

Cryogenic magnetometer measuring at once the three components X, Y and Z of the remanent magnetization (Natural Remanent Magnetization (NRM), Anhysteretic Remanent Magnetization (ARM), Isothermal Remanent Magnetization (IRM)) carried by standard size sample (25 mm x max 22 mm for cylinders, 22 mm side for cubes). The magnetometer is placed within the µmetal shielded room. See the description of zero-field furnaces and of alternating field demagnetization for the associated demagnetization modes.

Analyses performed with the instrument:

All remanent magnetizations (natural, anhysteretic, isothermal) on standard sedimen, archaeological baked clays and lava samples.

Contacts:

Gwenaël Hervé : 01.69.08.02.48 / gwenael.herve[a]lsce.ipsl.fr

Instrument description:

Bartington coil MS2C (22mm diameter; spatial resolution: 4.5 cm)

Analyses performed with the instrument:

Low-field magnetic susceptibility

Adapted for sediments sampled with u-channels

Contact:

Gwenaël Hervé : 01.69.08.02.48 / gwenael.herve[a]lsce.ipsl.fr

Instrument description:

Electromagnet (1.5 T or 2.3 T selon pole gaps) to investigate magnetic coercivities with high precision and high sensibility.

Analyses performed with the instrument:

• Hysteresis curves
• Isothermal remanent magnetization curves (acquisition and backfield)
• First Order Reversal Curves (FORCs)
• Measurements at variable temperatures (77 – 950 K)
• Can be applied to all kind of samples (rocks, sediments, soils, archaeological baked clays…)
• Measurements on small fragments or powders (a few 100 mg)

Contacts:

Gwenaël Hervé : 01.69.08.02.48 / gwenael.herve[a]lsce.ipsl.fr

Funding:

• CNRS/INSU
• DIM MAP MeV Project