Mass-Independent Isotope Fractionation in the Chemical Exchange Reaction of Chromium (III) Using a Crown Ether

Fujii, Toshiyuki; Moynier, Frédéric; Yin, Qing‐Zhu; Yamana, Hideaki

doi:10.1080/00223131.2008.10875968

Cited by 9 publications

(8 citation statements)

References 12 publications

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“…52 K D / 53 K D > 1. This preferential partitioning of lighter isotopes for the resin has previously been observed for Cr [48], as well as other elements, such as Ca [49], Fe [50], Cu and Zn [46], and Mg [51]. Such behavior is consistent with theoretical models based on differences in the vibrational energies of the isotopic substances, in which the isotopically lighter forms are predicted to partition more strongly for the exchanger because of their lower vibrational energy [16–18].…”

Section: Inter-species and Intra-peak Cr Isotope Fractionationsupporting

confidence: 72%

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

Larsen

Wielandt

Schiller

et al. 2016

Journal of Chromatography A

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Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that takes advantage of the slow reaction kinetics of de-chlorination of Cr in dilute HCl at room temperature. These procedures significantly improve cation chromatographic purification of Cr over previous methods and allow for high-purity Cr isotope analysis with a total recovery of >95%.

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Section: Inter-species and Intra-peak Cr Isotope Fractionationsupporting

confidence: 72%

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

Larsen

Wielandt

Schiller

et al. 2016

Journal of Chromatography A

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“…Our recent study on mass-independent isotope effect fractionation of Cr created in the crown ether extraction system proved that the isotopic mass balance between two phases was well preserved[23]. Hence, we employ ([ m Sn]/[ 120 Sn]) org calculated from D, ([ m Sn]/[ 120 Sn]) aq and ([ m Sn]/[ 120 Sn]) init (the isotope ratios of m Sn relative to 120 Sn in the starting material).…”

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confidence: 97%

Mass-independent isotopic fractionation of tin in chemical exchange reaction using a crown ether

Moynier¹,

Fujii²,

Télouk³

2009

Analytica Chimica Acta

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“…6 Most of these works represent the study of the reaction of an element with dicyclohexano-18crown-6 (DC18C6) crown ether. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Metal/metalloid was dissolved in aqueous solutions of HCl with different acid concentrations. Different species are predominant in these solutions depending on the HCl concentration.…”

Section: Discussionmentioning

confidence: 99%

“…Reactions of several other elements as aqueous chloro species with DC18C6 have been studied by Fujii and co-workers. [21][22][23][24][27][28][29][30][31][32][33][34][35][36][37] Most of them do not produce MIF (i.e. Fe) or show very insignificant MIF (i.e.…”

Section: Reactions Of Other Elements With Dc18c6 Crown-ethermentioning

confidence: 99%

Magnetic isotope effect and theory of atomic orbital hybridization to predict a mechanism of chemical exchange reactions

Epov

2011

Phys. Chem. Chem. Phys.

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A novel approach is suggested to investigate the mechanisms of chemical complexation reactions based on the results of Fujii with co-workers; they have experimentally observed that several metals and metalloids demonstrate mass-independent isotope fractionation during the reactions with the DC18C6 crown ether using solvent-solvent extraction. In this manuscript, the isotope fractionation caused by the magnetic isotope effect is used to understand the mechanisms of chemical exchange reactions. Due to the rule that reactions are allowed for certain electron spin states, and forbidden for others, magnetic isotopes show chemical anomalies during these reactions. Mass-independent fractionation is suggested to take place due to the hyperfine interaction of the nuclear spin with the electron spin of the intermediate product. Moreover, the sign of the mass-independent fractionation is found to be dependent on the element and its species, which is also explained by the magnetic isotope effect. For example, highly negative mass-independent isotope fractionation of magnetic isotopes was observed for reactions of DC18C6 with SnCl(2) species and with several Ru(III) chloro-species, and highly positive for reactions of this ether with TeCl(6)(2-), and with several Cd(II) and Pd(II) species. The atomic radius of an element is also a critical parameter for the reaction with crown ether, particularly the element ions with [Kr]4d(n)5s(m) electron shell fits the best with the DC18C6 crown ring. It is demonstrated that the magnetic isotope effect in combination with the theory of orbital hybridization can help to understand the mechanism of complexation reactions. The suggested approach is also applied to explain previously published mass-independent fractionation of Hg isotopes in other types of chemical exchange reactions.

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Mass-Independent Isotope Fractionation in the Chemical Exchange Reaction of Chromium (III) Using a Crown Ether

Cited by 9 publications

References 12 publications

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

Mass-independent isotopic fractionation of tin in chemical exchange reaction using a crown ether

Magnetic isotope effect and theory of atomic orbital hybridization to predict a mechanism of chemical exchange reactions

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