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Applications for LA-(MC)-ICP-MS
(text need some serious improvement)
Stable isotopes:
The two isotopes of lithium (7.5% of 6Li and 92.5% of 7 Li) have a relative mass difference of approximately 16.6% (larger than B with 10% and 16O-18O with 12.5%). Hence Li isotopicfractionation seems to be a promising tool to monitor low surface chemical processes. Lithiumisotopic composition varies within 60 ‰ in nature. At higher temperature, the fractionation factorapproach unity and crystal-liquid fractionation are smaller than 1 ‰. With the development ofMCICPMS, the related increase in the precision of the 6Li/7Li ratio measurement (0.5 ‰, 2σ) andsince olivine is the major Li host in the mantle, recent research focus on the upper mantlefractionation of the Li isotopes as a tracer of magmatic processes in peridotite and specially in arcenvironments. No laser ablation studies have been conducted so far on the lithium isotopiccomposition of mantellic material using laser ablation mainly because of the low Li concentrationof the olivine (few ppm) and the lack of internal mass bias correction.
Bouman, C., P. Z. Vroon, et al. (2002). Determination of lithium isotope compositions by MC-ICP- MS (Thermo Finnigan MAT Neptune). Goldschmidt conference abstract, Davos.
Marriott, C. S., N. S. Belshaw, et al. (2002). Lithium and calcium isotope fractionation in inorganically precipitated calcite: assessing their potential as a paleothermometer.
Goldschmidt conference abstract, Davos.
Tomascak, P. B., J. G. Ryan, et al. (2000). "Lithium isotope evidence for light element decoupling in the Panama subarc mantle." Geology 28: 507-510.
Nishio, Y. and S. Nakai (2002). "Accurate and precise lithium isotopic determinations of igneous rock samples using multi-collector inductively coupled plasma mass spectrometry." AnalyticaChimica Acta 456: 271-281.
Tomascak, P. B., R. W. Carlson, et al. (1999). "Accurate and precise determination of Li isotopic compositions by multi-collector sector ICP-MS." Chemical Geology 158: 145-154.
Tomascak, P. B., J. G. Ryan, et al. (2000). "Lithium isotope evidence for light element decoupling in the Panama subarc mantle." Geology 28: 507-510.
Tomascak, P. B., F. Tera, et al. (1999). "The absence of lithium isotope fractionation during basalt differentiation: New measurements by multicollector sector ICP-MS." Geochimica etCosmochimica Acta 63: 907-910.
Tomascak, P. B., E. Widom, et al. (2002). "The control of lithium budgets in island arcs." Earth & Planetary Science Letters 196: 227-238.
The two isotopes of Boron (19.9% of 10 Li and 80.1% of 11 Li) have a relative mass difference of approximately 10%. A very large isotopic fractionation of the B isotopes is observedin the nature, from +60‰ in marine evaporitic brines to -30‰ in non-marine evaporites mainlybecause of its mobility during both magmatic and fluid related processes within a large temperaturerange. The B isotopic fractionation is relatively insensitive to oxydo-reduction reactions. Ion probetechniques provide poor precision (3‰ at 2s) and time consuming TIMS analyses involve positiveions from alkali borates provide reproductibilities for the standard 951 from 0.2‰ to 1‰ (2s).
More recent TIMS techniques using negative ions provide better precision (<0.7‰). Lécuyer et al(2002) have recently developed a simple protocol for the chemical separation of B from seawater,carbonate, phosphate and silicates, which provide an external reproductibility on the standard 951of ±0.3δ at 2σ using a MCICPMS. This method requires at least 2 µg of B from the startingmaterial. No laser ablation boron isotope analyses has been conducted so far although thistechnique has great potential for the isotopic measurement of B-rich phases such as tourmalines,which are also hard to dissolve using basic wet chemistry procedures. Tourmaline is an idealpetrogenetic and ore-genetic tracer and its isotopical composition may record the primary isotopicalsignature of the hydrothermal ore-forming event, due to its refractory nature that is hardly altered though post-ore hydrothermal alteration and metamorphism (Jiang 2001, Phys. Chem. Earth,26:851-858).
Aggarwal, J. K., K. Mezger, et al. (1999). "Precise and accurate determination of boron isotope ratios by multiple collector ICP-MS: origin of boron in the Ngawha geothermal system, NewZeland." ES tansaction.
Lécuyer, C., P. Grandjean, et al. (2002). "11B/10B analysis of geological materials by ICP-MS plasma 54: application to the boron fractionation between brachiopod calcite and seawater."Chemical Geology 186: 45-55.
Magnesium has 3 naturally occurring isotopes 24Mg, 25Mg and 26Mg, with relative abundance of
78.99%, 10% and 11.01%, respectively. Natural variations of the isotopic composition of Mg may
arise through (Galy et al, 2001):
Stellar nucleosynthesis and incorporation of pre-solar grains into meteorites Isotopic fractionation through volatilization / condensation reactions Isotope fractionation during low temperature fluid/rock interactions Kinetic and thermodynamic isotope effects accompanying biological incorporation andrejection Previous analyses using TIMS have shown relatively low terrestrial variations (few ‰) with a errorof (1‰ to 2‰). Recent MCICPMS studies have demonstrated a repeatability of the standard SRM980 between 0.12‰ and 0.06‰ (Galy et al, 2001). Galy et al have shown a terrestrial variability on δ26Mg of 4‰ for nine samples. More recently Galy et al (2002) have demonstrated a 4.13‰ and2.14‰ isotopic variations respectively for d26Mg and d25Mg while analysing speleothems andtheir associated host-rocks and waters.
The main analytical problems with Mg isotopes measurements are related to the presence ofmolecular interferences on all isotopes, instrumental fractionation and matrix effects. Galy et al(2001) have shown that matrix effects are relatively significant and that only magnesia, magnesiteand chlorophyll would permit a direct measurement without previous chemical separation of Mg.
The use of high resolution instrument to correct for the interferences might improve this matrixdependency. Young et al (2002) have analyzed Mg isotopic composition of the Allende meteoriteusing laser ablation MCICPMS and represent so far the only published result on in-situmeasurement. For this particular experiment, the addition of concomitant element during theablation didn't significantly shift the Mg isotopic composition.
Alard, O., K. W. Burton, et al. (2002). Mg-isotopes in terrestrial and extraterrestrial olivine.
Goldschmidt conference abstract, Davos.
Chang, V. T.-C., N. Belshaw, et al. (2002). Mg and Ca isotope fractionation during CaCO3 biomineralization. Goldschmidt conference abstract, Davos.
Galy, A., N. S. Belshaw, et al. (2001). "High-precision measurement of magnesium isotopes by multiple-collector inductively coupled plasma mass spectrometry." Int. J. Mass Spectrom 208:89-98.
Galy, A. (2002). Isotopic composition of dissolved Mg in natural waters. Goldschmidt conference Galy, A., M. Bar-Matthews, et al. (2002). "Mg isotopic composition of carbonate: insight from speleothem formation." EPSL 201: 105-115.
Young, E. D., R. D. Ash, et al. (2002). "Mg isotope heterogeneity in Allende meteorite measured by UV laser ablation-MC-ICPMS and comparisons with O isotopes." Geochimica etCosmochimica Acta 66: 683-698.
Silica is the second most abundant element after oxygen in the silica Earth and its isotopic composition is of major interest for a large range of topics in the Earth sciences, ranging fromcontinental weathering to biological productivity in the ocean (Vroon et al, 2002). The threeisotopes of silica (92.23% of 28Si, 4.67% of 29Si and 3.1% of 30Si) have a relative mass differenceof approximately 7% between 28Si and 30Si. Not much information is available from the literatureabout the natural isotopic variation of Si isotopes. Ziegler et al (2002 have noticed up to -1.5‰ Si-isotopic differences between solutions and solids in weathered soil profiles. These measurementsuffer from classic polyatomic interferences such as CO, N2 on 28Si and 29Si; CO, NO and N2Hon 30Si. Using High resolution (Vroon et al, 200) obtain a reproductibility better than 0.17‰ on a10ppm solution for a 3 hour measurement. Using a Nu and its zoom optics, Alleman et al (2002)were able to measure Si isotopes in dynamic mode, while monitoring the Mg isotopes as an internalstandard. In this last experiment, the reproductibility were better than 0.15‰ and individualprecision better than 0.05‰. the mass bias for this mass range is about 12%.
Alleman, L., D. Cardinal, et al. (2002). New developments in measuring silicon isotopes by MC- ICP-MS. Goldschmidt conference abstract, Davos.
Vroon, P. Z., C. J. Beets, et al. (2002). Silicon isotopic composition of sponge spicules determined by MC-ICPMS. Goldschmidt conference abstract, Davos.
Ziegler, K., O. A. Chadwick, et al. (2002). The δ30Si values of soil weathering profiles: indicators of Si pathways at the lithosphere/hydro(bio)sphere interface. Goldschmidt conferenceabstract, Davos.
Calcium is the fifth most abundant element in the silicate Earth (after O, Si, Al, Fe). Calcium has six stable isotopes (96.941% of 40Ca, 0.647% of 42Ca, 0.135% of 43Ca, 2.086% of 44Ca,0.004% of 46Ca, 0.187% of 48Ca) and a relative mass difference of 4.7% between 42Ca and 44Ca.
A study of Ca isotopes in natural samples reveals a variation up to 4‰ on 44Ca/40Ca using TIMS.
Due to isobaric interference of 40Ca and 40Ar the natural variation measured by ICP between44Ca/42Ca is assumed to be smaller. Using double Ca spike for mass fractionation correction,TIMS measurements reach the precision of 0.1‰ although more recent TIMS analyses claimprecision down to 25 ppm (Tuttas & Shwieters, Goldsmidt 2002). Ca isotope fractionation has beenobserved in environmental samples as well as in medical applications.
Halicz, L., A. Galy, et al. (1999). "High-precision measurement of calcium isotopes in carbonates and related material by multi collector inductively coupled plasma mass spectrometry."Journal of Analytical Atomic Spectrometry 14: 1835-1838.
Marriott, C. S., N. S. Belshaw, et al. (2002). Lithium and calcium isotope fractionation in inorganically precipitated calcite: assessing their potential as a paleothermometer.
Goldschmidt conference abstract, Davos.
The five isotopes of titanium (8% of 46Ti, 7.3% of 47Ti, 73.8% of 48Ti, 5.5% of 49Ti and 5.4% of 50Ti) have a relative mass difference of approximately 8.7% between 46Ti and 50Ti. TheTi isotopic system is largely unexplored although titanium is an element of considerablegeochemical and cosmochemical importance (Guo et al, 2002). Development in solutionMCICPMS unable long term reproductibility of δ47Ti, δ 48Ti, δ 49Ti and δ 50Ti respectively at0.4,0.6, 0.7 and 0.8 ε unit: ( Ti/46Ti) /(xTi/46Ti) −1)*10000 An overall variation of about ε50Ti units has been observed between a variety of samples such as basalts, mantle xenoliths, loess, chondrites and achondrites (Guo et al, 2002).
Chen, H.-W. and T. Lee (2002). Pitfalls of Ti isotopic measurement by multi-collector-ICP-
MS. Goldschmidt conference abstract, Davos.
Guo, Y., A. Makishima, et al. (2002). High precision measurement of Ti isotopes in terrestrial and extraterrestrial materials. Goldschmidt conference abstract, Davos.
Iron is the fourth most abundant element in the silicate Earth and have four stable isotopes (5.8% of 54Fe, 91.72% of 56Fe, 2.2% of 57Fe, 0.28% of 58Fe) and a relative mass difference of7.4% between 54Fe and 58Fe.
Matthews, A., H. Morgans-Bell, et al. (2002). Cyclic variations of iron isotope composition during diagenesis: the Kimmeridge clay formation (UK). Goldschmidt conference abstract, Davos.
Mullane, E., R. J. Herrington, et al. (2002). Iron isotope fractionation in an Archaean BIF sample suite. Goldschmidt conference abstract, Davos.
Ohno, T., I. Kouge, et al. (2002). Iron isotopes in human blood. Goldschmidt conference abstract, Poitrasson, F., N. Teutsch, et al. (2002). Iron isotope signature of the inner solar system.
Goldschmidt conference abstract, Davos.
Von Blanckenburg, F. and T. Walczyk (2002). Iron isotope fractionation by the human body, animals and plants. Goldschmidt conference abstract, Davos.
Wiederhold, J. G. and F. Von Blanckenburg (2002). Iron isotope variations in a complete natural soil catena with lateral iron mobilization and reprecipitation. Goldschmidt conferenceabstract, Davos.
Williams, H., D.-C. Lee, et al. (2002). Iron isotope composition of mid-ocean ridge basalts and mantle peridotites. Goldschmidt conference abstract, Davos.
Zhu, X. K., R. K. O'Nions, et al. (2000). "Secular variation of iron isotopes in North Atlantic Deep Ni
Quitté, G. and A. N. Halliday (2002). Nickel isotopes in meteorites: constraints on the early solar
system. Goldschmidt conference abstract, Davos.
Cu & Zn
Copper has two stable isotopes of mass 63 and 65, whose average abundances are 69.17% and 30.83% respectively (Shields et al, 1964). Zinc has five isotopes of mass 64, 66, 67, 68 and 70,whose average abundances are 48.63%, 27.90%, 4.10%, 18.75% and 0.62% respectively. Naturalisotopic variation between silicate, ores, sediments, biological materials are within a few ‰.
These 2 isotopic system are potentially useful geochemical and biological tracers.
Gale, N. H., A. P. Woodhead, et al. (1999). "Natural variations detected in the isotopic composition of copper . possible applications to archaeology and geochemistry." International Journal ofMass Spectrometry 184: 1-9.
Maréchal, C. and F. Albarède (2002). "Ion-exchange fractionation of copper and zinc isotopes." Geochimica et Cosmochimica Acta 66: 1499-1509.
Maréchal, C. N., E. Nicolas, et al. (2000). "Abundance of zinc isotopes as a marine biochemical Zhu, X. K., R. K. O'Nions, et al. (2000). "Determination of natural Cu-isotope variation by plasma- source mass spectrometry : implications for use as geochemical tracers." Chemical Geology163: 139-149.
Zhu, X. K., R. J. P. Williams, et al. (2002). "Mass fractionation processes of transition metal Reference:
Galy, A., O. S. Pokrovsky, et al. (2002). Ge-isotopic fractionation during its sorption on goethite: an experimental study. Goldschmidt conference abstract, Davos.
Hirata, T. (1997). "Isotopic variations of germanium in iron and stony iron meteorites." Geochimica The six isotopes of selenium (0.89% of 74Se, 9.36% of 76Se, 7.63% of 77Ti, 23.78% of 78Ti, 49.61% of 80Se and 8.73% of 82Se) have a relative mass difference of approximately 11% between74Se and 80Se. Due to the low isotopical abundance of 74Se, 76Se is preferred (about 8% relativemass difference). Because of its toxicity, its different valence state and its large number of isotopes,selenium is a potential tracer of geological and biological tracer (Rouxel et al, 2002). Using a newpre-concentration and separation technique Rouxel et al (2002) were able to measure the differentselenium isotopes with an external precision of 0.25‰. The overall isotopical variation fromenvironmental, deep-sea sediments, hydrothermal deposits, igneous rocks and meteorites are about8‰ on δ82/76Se. No experiments have been conducted so far with laser ablation.
Rouxel, O., J. Ludden, et al. (2002). "Natural variations of Se isotopic composition determined by hydride generation multiple collector inductively coupled plasma mass spectrometry." GCA66: 3191-3199.
Cloquet, C., J. Carignan, et al. (2002). High precision cadmium isotopic measurements by MC- ICP-MS. Goldschmidt conference abstract, Davos.
Wombacher, F., M. Rehkamper, et al. (2002). Stable isotope compositions of cadmium in stony meteorites. Goldschmidt conference abstract, Davos.
Lee, D.-C. and A. N. Halliday (1995). "Precise determinations of the isotopic compositions and atomic weights of molybdenum, tellurium, tin and tungsten using ICP magnetic sectormultiple collector mass spectrometry." International Journal of Mass spectrometry and ionProcesses 146/147: 35-46.
Luais, B., P. Telouk, et al. (1997). "Precise and accurate neodymium isotopic measurements by plasma-source mass spectrometry." Geochimica Cosmochimica Acta 61: 4847-4854.
Vance, D. and M. Thirlwall (2002). "An assessment of mass discrimination in MC-ICPMS using Nd isotopes." Chemical Geology 185: 227-240.
Woodland, S. J., M. Rehkamper, et al. (2002). High precision MC-ICP-MS measurement of Ag isotopic ratios. Goldschmidt conference abstract, Davos.
Evans, R. D. and P. J. Dillon (2002). Determination of variations in isotope ratios of Hg.
Goldschmidt conference abstract, Davos.
Nielsen, S. G., M. Rehkämper, et al. (2002). Isotopic compositions and concentrations of eastuarine thallium. Goldschmidt conference abstract, Davos.
Rehkämper, M. and A. N. Halliday (1999). "The precise measurement of T1 isotopic compositions by MC-ICPMS: Application to the analysis of geological materials and meteorites."Geochimica et Cosmochimica Acta 63: 935-944.
Radiogenic isotopes:
Strontium isotopic composition is an important geochemical tracer. It is used in a wide range of applications, including tracing water sources, matle processes and in geochronological system frb-Sr. Th natural varition in the 87sr/86Sr ratio is derived from the radioacive decay of 87Rb to87Sr (Ehrlich et al, 2001). Trontium have 4 isotopes (0.56% of 84Sr, 9.86% of 86Sr, 7% of 87Srand 82.58% of 88Sr), 3 of which are stable (84Sr, 86Sr and 88Sr). TIMS is commonly used forprecise Sr isotopic meaurements with internal and extrnal precision respectively of about 0.02‰and 0.01‰. Erlich et al (2001) have recently discussed on the isotopic measurement usingMCICPMS and claim a precision of about 0.02‰ using a faster acquisition time and higher TDSsamples. The precision of Sr isotopes is faciliate by the use of an internal sable isotopic pair(84/88Sr) to correct for the mass bias of the instrument. Recently the Rb-Sr isotopic mesurementhas been improved by using a Zr spike while measuring Rb isotopic composition (Waight et al,2002). Aso be careful about the Kr correction on 86Sr (see earlier section on interferences). The Srisotopes composition could be used iether as an isotopic tracer while abling calcium, phosphate-rich material (plagioclase, apatite, bones etc.) or as a geochronometer together with Rb isotopes.
The following are just some examples of applications.
Sr isotopes fingerprinting of magmatic processes through the in-situ analysis of Sr isotopiccomposition of plagioclase.
Sr isotopes geochronology on Palaeozoic carbonates ? In marine carbonate, the 87Sr/86Sr ratio reflects the isotopic composition of sea-water fromwhich they precipitate. Over geological history, the isotopic composition of sea-water hasvaried considerably (see figure below) and thus, the isotopic composition of Sr in carbonates isa useful tool in reconstruction of geological history. Strontium isotope stratigraphy is findingwidespread use for dating and correlation of sediments.
Sea-water Sr evolution curve for the Palaeozoic (McArthur publications) Error on 87/86Sr determination at variable spot size and with 1ppb solution for 3 mnacquisition.
-Sr isotopic in skeletal elements (bones, teeth etc.) could be useful to infer the geographic regionthat an animal or human inhabited, because different regions tend to have distinct Sr isotopiccompositions.
Christensen, J. N., A. N. Halliday, et al. (1995). "In situ Sr isotopic analysis by laser ablation." Earth and Planetary Science Letters 136(1-2): 79-85.
Davidson, J. P., F. J. Tepley III, et al. (2001). "Magma recharge, contamination and residence times revealed by in-situ laser ablation isotopic analysis of feldspar in volcanic rocks." Earth andPlanetary Science Letters 184(427-442).
Prohaska, T., C. Latkoczy, et al. (2002). "Investigation of Sr isotope ratios in prehistoric human bones and teeth using laser ablation ICP-MS and ICP-MS after Rb/Sr separation." JAAS17(8): 887-891.
Ehrlich, S., I. Gavrieli, et al. (2001). "Direct high-precision measurements of the Sr-87/Sr-86 isotope ratio in natural water, carbonates and related materials by multiple collectorinductively coupled plasma mass spectrometry (MC-ICP-MS)." Journal of Analytical AtomicSpectrometry 16: 1389-1392.
Waight, T., J. A. Baker, et al. (2002). "Rb isotope dilution analyses by MC-ICP-MS using Zr to correct for mass fractionation: towards improved Rb-Sr geochronology ?" Chemical Geology186: 99-116.
Hirata, T. and T. Yamaguchi (1999). "Isotopic analysis of zirconium using enhanced sensitivity- laser ablation-multiple collector-inductively coupled plasma mass spectrometry." Journal ofAnalytical Atomic Spectrometry 14: 1455-1459.
Hirata, T. (2001). "Determinations of Zr isotopic compositions and U-Pb ages for terrestrial and extraterrestrial Zr-bearing minerals using laser ablation-inductively coupled plasma massspectrometry: implications for Nb-Zr isotopic systematics." Chemical Geology 176: 323-342.
Sanloup, C., J. Blichert-Toft, et al. (2000). "Zr anomalies in chondrites and the presence of 92Nb ib the early solar system." Earth and Planetary Science Letters: 75-81.
Barling, J., G. L. Arnold, et al. (2001). "Natural mass-dependent variations in the isotopic composition of molybdenum." EPSL 193: 447-457.
Lee, D.-C. and A. N. Halliday (1995). "Precise determinations of the isotopic compositions and atomic weights of molybdenum, tellurium, tin and tungsten using ICP magnetic sector multiple collector mass spectrometry." International Journal of Mass spectrometry and ionProcesses 146/147: 35-46.
Siebert, C., T. F. Nägler, et al. (2001). "Determination of molybdenum isotope fractionation by double-spike multicollector inductively coupled plasma mass spectrometry." G3 2.
Siebert, C., T. F. Nägler, et al. (2002). The oceanic Mo cycle over the üast 60a. Goldschmidt Reference:
Carlson, R. W. and E. H. Hauri (2001). "Extending the Pd-107-Ag-107 chronometer to low Pd/Ag meteorites with multicollector plasma-ionization mass spectrometry." GeochimicaCosmochimica Acta 65(11): 1839-1848.
Albarède, F., J. Blichert-Toft, et al. (2000). "Hf-Nd isotope evidence for a transient dynamic regime in the early terrestrial mantle." Nature 404: 488-490.
Griffin, W. L., N. J. Pearson, et al. (2000). "The Hf isotope composition of cratonic mantle: LAM- MC-ICPMS analysis of zircon megacrysts in kimberlites." Geochimica et CosmochimicaActa 64: 133-147.
Blichert-Toft, I., F. A. Frey, et al. (1999). "Hf isotope evidence for pelagic sediments in the source of Hawaiian." Science 285: 879-882.
Blichert-Toft, J. and F. Alabarède (1997). "The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system." Earth and Planetary Science Letters 148: 243-258.
Blichert-Toft, J., F. Albarède, et al. (1999). "The Nd and Hf isotopic evolution of the mantle through the Archean. Results from the Isua supracrustals, West Greenland, and from theBirimian terranes of West Africa." Geochimica et Cosmochimica Acta 63: 3901-3914.
Blichert-Toft, J. and N. T. Arndt (1999). "Hf isotope compositions of komatiites." Earth & Planetary Science Letters 171(3): 439-451.
Blichert-Toft, J., C. Chauvel, et al. (1997). "Separation of Hf and Lu for high-precision analysis of rock samples by magnetic sector-multiple collector ICP MS." Contribution to Mineralogy andPetrology 127: 248-260.
Lee, D.-C., A. N. Halliday, et al. (1999). "Hafnium isotope stratigraphy of ferromanganese crsuts." Lee, D.-C. and A. N. Halliday (1996). "Hf-W isotopic evidence for rapid accretion and differentiation in the Early Solar System." Science 274: 1876-1879.
Lee, D.-C. and A. N. Halliday (2000). "Hf-W internal isochrons for ordinary chondrites and the initial 182Hf/180Hf of the slar system." Chemical Geology 169: 35-43.
Stevenson, R. K., M. Bizzaro, et al. (2002). Hf isotope composition of 3Ga komatiites from Ontario, Canada. Goldschmidt conference abstract, Davos.
Thirlwall, M. F. and A. J. Walder (1995). "In situ hafnium isotope ratio analysis of zircon by inductively coupled plasma multiple collector mass spectrometry." Chemical Geology 122(1-4): 241-247.
Vervoort, J. D., P. J. Patchett, et al. (2000). "Hf-Nd isotopic evolution of the lower crust." Earth and Planetary Science Letters 181: 115-129.
Halliday, A. N. (2000). "HF-W chronometry and inner solar system accretion rates." Space Science Halliday, A. N. and D. C. Lee (1999). "Tungsten isotopes and the early development of the Earth and Moon." Geochimica et Cosmochimica Acta 63: 4157-4179.
Quitté, G., J.-L. Birk, et al. (2000). "182Hf-182W systematics in eucrites: the puzzle of iron segregation in the early solar system." Earth and Planetary Science Letters 184: 83-94.
Alard, O., W. L. Griffin, et al. (2000). "Non-chondritic distribution of the highly siderophile elements in mantle sulfides." Nature 407: 891-894.
Hirata, T., M. Hattori, et al. (1998). "In-situ osmium isotope ratio analyses of iridosmines by laser ablation-multiple collector-inductively coupled plasma mass spectrometry." ChemicalGeology 144(3-4): 269-280.
Pearson, N. J., O. Alard, et al. (2002). "In situ measurement of Re-Os isotopes in mantle sulfides by laser ablation multicollector-inductively coupled plasma mass spectrometry: Analyticalmethods and preliminary results." Geochimica et Cosmochimica Acta 66: 1037-1050.
Collerson, K. D., B. S. Kamber, et al. (2002). "Applications of accurate, high precision Pb isotope ratio measurement by multi-collector ICP-MS." Chemical Geology 188: 65-83.
Doucelance, R. and G. Manhès (2001). "Reevaluation of precise lead isotope measurements by thermal ionization mass spectrometry: comparison with determinations by plasma sourcemass spectrometry." Chemical geology 176: 361-377.
Ehrlich, S., Z. Karpas, et al. (2001). "High precision lead isotope ratio measurements by multicollector-ICP-MS in variable matrices." Journal of Analytical Atomic Spectrometry 16:975-977.
Hirata, T. (1996). "Lead isotopic analyses of NIST standard reference materials using multiple collector inductively coupled plasma mass spectrometry coupled with a modified externalcorrection method for mass discrimination effect." Analyst 121: 1407-1411.
Thirlwall, M. F. (2002). "Multicollector ICP-MS analysis of Pb isotopes using a 207Pb-204Pb double spike demonstrates up to 400 ppm/amu systmatic errors in Tl-normalisation."Chemical Geology 184: 255-279.
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Figure 5_1: The principle of the concordia diagram (from Machado and Simonetti, 2001)
The U-Pb system is an important geochronological tool.
Two isotopes of U decay to Pb with very different half-lives. Therefor chemical processes will notchange the ratio of the two U isotopes to each other and will not change the ratio of the two Pbdaughter isotopes to each other.
Zircon is relatively insensitive to geological processes such as chemical alteration, erosion,sedimentation, metamorphism, anatexis, and is a ubiquitous accessory mineral in magmatic rocks.
Recent analytical developments have demonstrated the benefits taken from the geochemical andisotopical information provided by the ubiquitous and magmatic zircon phase. Over the last fewyears, different groups have successfully used LA-(MC)-ICP-MS for the in-situ determination ofU-Pb isotopic measurement in zircon (Thirlwall & Walder 1995, Hirata & Nesbit 1995, Machado etal. 1996, Scott & Gauthier 1996, Fernandez-Suarez et al. 2000, Hirata 1997, Horn et al. 2000,Ballard et al. 2001, Bruguier et al. 2001, Ketchum et al. 2001, Knudsen et al. 2001, Li et al. 2001,Machado & Simonetti 2001, Kosler et al. 2002). Some of these work have focussed on thesedimentary provenance of the zircon (Machado et al. 1996, Scott & Gauthier 1996, Fernandez-Suarez et al. 2000, Ketchum et al. 2001, Ko_ler et al. 2002, Hidaka et al. 2002). Previous studies(Morton et al. 1996, Fernandez-Suarez et al. 2000) have shown in particular that, in order to isolatea major sedimentary source component, it is required to analyse a large number of samples. LA-ICP-MS is the method of choice on a timely and cost effective basis in comparison with otherconventional dating technique for zircon age dating of Proterozoic and Archean rocks.
Using quadrupole based instrument, recent studies have shown that, with the proper errorpropagation, the precision of U-Pb age is only slightly worse than SIMS-based ion probe dating(Horn et al, 2000; Kosler et al, 2002). Similar or better errors are expected using magnetic sectorICP-MS because of a better ion transmission and peak shape. However the error in U-Pb zircon agedetermination is related to (1) U-Pb fractionation during the ablation process (2) the ability toaccurately correct for the mass bias induced by the ICP source (3) the ability to measure Pb204 andcorrect for common lead.
(2) Kosler et al (2001) mixed the ablated sample with mixed desolvated solution of 233U enriched and thallium using an AridusTM. Horn et al (2000) prefer using 235U instead of233U but in this case a correction for natural 235U is necessary.
Kosler et al (2001) technique summary:
- Monitor Hg202, Pb204-206-207-208, Tl203-205,U233-235-238 (monitor 232Th for Thenriched samples such as monazite for 232Th-208Pb decay scheme)- Used mixed Ar-He gas in the sample cell later on mixed again with 10ppb Tl and 233U Raster a 40*40 µm square on your zircon, while defocus the beam, for 60s.
Use higher sample time (dwell time) for isotopes such as Pb204-207 because of their lowcount rate Scan as fast as possible (lower settling time) and acquire data Correct for the mass bias using 235U/238U Correct for remaining Pb/U fractionation using a least square linear regression R0 = intercept valueS = slopeT = laser ablation timeR0 is calculated using the following equation: ‘n = number of isotope ratioti and ri are individual time and isotopic ratio The uncertainty associated to the fractionation-correction ratio could be calculated using thefollowing equation: U series
Gavrieli, I., M. Bar-Matthews, et al. (2002). Hydrological stability in carbonate aquifers over the
last 250kyr as reflected by 234U/238U in groundwater, speleothems and tufa. Goldschmidt
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Benoit Petit-Demouliere . Franck Chenu . Michel BourinForced swimming test in mice: a review of antidepressant activityReceived: 11 June 2004 / Accepted: 21 September 2004 / Published online: 18 November 2004forced swimming test (FST) remains one of the most usedtools for screening antidepressants. Objective: This paperreviews some of the main aspects of the FST in mice. Mostof the sensitivi


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