Isotopic Composition Of Copper Research Articles

THE METHOD FOR Cu AND Zn ISOTOPE RATIO DETERMINATION BY MC ICP-MS USING THE AG MP-1 RESIN

The isotopic composition of copper is of great interest for researchers in various fields of science, geochemistry and hydrology in particular, wherein the consideration is being given to the variations in the isotopic composition of the Earth’s crust, extraterrestrial matter, and water basins, as well as to the origin and transfer of matter. Zn isotopes appear to be promising for identifying the sources and pathways of the environmental pollution. The aim of this study involves the refinement and validation of the zinc and copper isotopic ratio determination methodology covering the whole process from sample digestion to MC ICP-MS measurements. For this reason, as well as to assess the suitability of the methodology for the analysis of environmental samples, Zn and Cu isotopic analysis of the BHVO-2, BCR-2 and AGV-2 USGS certified reference materials has been performed. The method for determination of Cu and Zn stable isotope ratios by multi-collector inductively coupled plasma mass spectrometry in environmental samples is developed. The application of the AG MP-1 resin with optimized layer parameters (resin bed height 3.5 cm, diameter 1 cm) provides the high-purity Cu and Zn fractions. The method is characterized by high throughput and adequate analytical figures of merit when using the standard-sample bracketing technique for mass bias correction. The procedural blanks related to chemical dissolution and ion exchange procedures are lower than 1 and 3 ng for Cu and Zn, respectively, assuring no blank effect on the isotopic composition of samples. The accuracy and precision obtained for Cu and Zn isotope measurements in the BHVO-2, BCR-2 and AGV-2 geological certified reference materials demonstrate good agreement with the reference values published.

Metal isotope signatures from lava-seawater interaction during the 2018 eruption of Kīlauea

The 2018 eruption of Kīlauea was associated with massive input of molten lava into the coastal ocean, which altered seawater chemistry and increased phytoplankton production. In seawater plumes advected away from the site of lava entry, we observed elevated concentrations of over a dozen metals relative to background seawater and unique isotopic compositions of Fe, Cu, Ni, Cd and Zn. The δ56Fe of iron released from lava was lower than basaltic, riverine and coastal iron from Hawaiʻi, but similar to observations of other high-temperature hydrothermal vent fluids. However, rapid precipitation led to only modest enrichments in dissolved iron (<10 nM), with increasing dissolved δ56Fe likely due to fractionation associated with ligand-mediated dissolution of particulate Fe. The isotopic composition of copper and nickel show evidence for two-endmember mixing between background seawater and a lava source. While the Ni isotopic endmember reflected basaltic δ60Ni, endmember δ65Cu, δ66Zn, and δ114Cd were isotopically lighter than basalt. We hypothesize that high diffusivity and volatility of chalcophile elements leads to strong kinetic fractionation in rapidly cooling lavas, similar to Cu, Zn and Cd isotopic patterns observed in tektites. The isotopic signatures of Cu and Ni observed during the 2018 eruption of Kīlauea far exceed their normal seawater range and may be useful for identifying large-scale lava input into ocean waters during the formation of large igneous provinces and other episodes of volcanism.

Antibiotic treatment affects the expression levels of copper transporters and the isotopic composition of copper in the colon of mice

Copper is a critical enzyme cofactor in the body but also a potent cellular toxin when intracellularly unbound. Thus, there is a delicate balance of intracellular copper, maintained by a series of complex interactions between the metal and specific copper transport and binding proteins. The gastrointestinal (GI) tract is the primary site of copper entry into the body and there has been considerable progress in understanding the intricacies of copper metabolism in this region. The GI tract is also host to diverse bacterial populations, and their role in copper metabolism is not well understood. In this study, we compared the isotopic fractionation of copper in the GI tract of mice with intestinal microbiota significantly depleted by antibiotic treatment to that in mice not receiving such treatment. We demonstrated variability in copper isotopic composition along the length of the gut. A significant difference, ∼1.0‰, in copper isotope abundances was measured in the proximal colon of antibiotic-treated mice. The changes in copper isotopic composition in the colon are accompanied by changes in copper transporters. Both CTR1, a copper importer, and ATP7A, a copper transporter across membranes, were significantly down-regulated in the colon of antibiotic-treated mice. This study demonstrated that isotope abundance measurements of metals can be used as an indicator of changes in metabolic processes in vivo. These measurements revealed a host-microbial interaction in the GI tract involved in the regulation of copper transport.

Geochemistry, mineralogy, and isotope composition of Pb, Zn, and Cu in primary ores, gossan and barren ferruginous crust from the Perkoa base metal deposit, Burkina Faso

Gossan at the Perkoa deposit of stratabound lead and zinc ores (Burkina Faso) is composed of hematite, goethite, clay minerals, minerals of the brucite group and sulfates (corkite, alunite, natroalunite, hinsdalite and hidalgonite). Residual quartz contains inclusions of chalcopyrite, sphalerite and cinnabar. Compared with the primary ores, the gossan is especially enriched with As, Ba, Pb, P, and Sb. On the other hand, the contents of Ag, Co, Cu, Hg, Mo, Ni, and particularly Zn are significantly lower. However, compared with the barren ferruginous crust in the same area, the gossan is significantly enriched in most of chemical elements, namely As, Pb, Sb, and Zn and to lesser extent also in Ag, Ba, Cd, Mo, S, and Sr.The isotopic composition of lead in massive primary ore and in gossan is practically identical. However, the isotopic composition of lead in disseminated ores, the bleached gossan envelope, and in mineralized soils in the Perkoa area is very variable and reflects mixing of ore and lithogenic lead. The 206/207Pb ratio in barren soils and ferruginous crusts is much higher compared with gossan and related altered rocks.Compared to massive ore (δ65Cu=+1.91 to +2.17‰ and δ66Zn=+0.30 to +0.36‰, respectively), the gossan is depleted in heavy isotopes of copper and zinc (δ65Cu=−0.02 to −0.58 and δ66Zn=−0.10 to −0.88‰, respectively). The chemical weathering of sulfide-rich rocks thus gives rise to considerable variations in Cu isotopes (median: −2.36‰, Δ65Cugossan–massive ore), and minor changes in Zn isotopes (median: −0.73‰, Δ66Zn gossan–massive ore). Isotopic composition of copper in gossan and lateritic soil sampled in the vicinity of gossan is similar but differs from barren laterite duricrust which is more depleted in the 65Cu isotope. In zinc, no differences were proved between the δ66Zn values in the gossan and those in the soil and ferruginous crust.

Hypoxia induces copper stable isotope fractionation in hepatocellular carcinoma, in a HIF-independent manner.

Hepatocellular carcinoma (HCC) is the most frequent type of primary liver cancer, with increasing incidence worldwide. The unrestrained proliferation of tumour cells leads to tumour hypoxia which in turn promotes cancer aggressiveness. While changes in the concentration of copper (Cu) have long been observed upon cancerization, we have recently reported that the isotopic composition of copper is also altered in several types of cancer. In particular, we showed that in hepatocellular carcinoma, tumour tissue contains heavier copper compared to the surrounding parenchyma. However, the reasons behind such isotopic signature remained elusive. Here we show that hypoxia causes heavy copper enrichment in several human cell lines. We also demonstrate that this effect of hypoxia is pH, HIF-1 and -2 independent. Our data identify a previously unrecognized cellular process associated with hypoxia, and suggests that in vivo tumour hypoxia determines copper isotope fractionation in HCC and other solid cancers.

Equilibrium isotopic fractionation of copper during oxidation/reduction, aqueous complexation and ore-forming processes: Predictions from hybrid density functional theory

Copper exists as two isotopes: 65Cu (∼30.85%) and 63Cu (∼69.15%). The isotopic composition of copper in secondary minerals, surface waters and oxic groundwaters is 1–12‰ heavier than that of copper in primary sulfides. Changes in oxidation state and complexation should yield substantial isotopic fractionation between copper species but it is unclear to what extent the observed Cu isotopic variations reflect equilibrium fractionation. Here, I calculate the reduced partition function ratios for chalcopyrite (CuFeS2), cuprite (Cu2O), tenorite (CuO) and aqueous Cu+, Cu+2 complexes using periodic and molecular hybrid density functional theory to predict the equilibrium isotopic fractionation of Cu resulting from oxidation of Cu+ to Cu+2 and by complexation of dissolved Cu. Among the various copper(II) complexes in aqueous environments, there is a significant (1.3‰) range in the reduced partition function ratios. Oxidation and congruent dissolution of chalcopyrite (CuFeS2) to dissolved Cu+2 (as Cu(H2O)5+2) yields 65–63δ(Cu+2–CuFeS2)=3.1‰ at 25°C; however, chalcopyrite oxidation/dissolution is incongruent so that the observed isotopic fractionation will be less. Secondary precipitation of cuprite (Cu2O) would yield further enrichment of dissolved 65Cu since 65–63δ(Cu+2–Cu2O) is 1.2‰ at 25°C. However, precipitation of tenorite (CuO) will favor the heavy isotope by +1.0‰ making dissolved Cu isotopically lighter. These are upper-limit estimates for equilibrium fractionation. Therefore, the extremely large (9‰) fractionations between dissolved Cu+2 (or Cu+2 minerals) and primary Cu+ sulfides observed in supergene environments must reflect Rayleigh (open-system) or kinetic fractionation. Finally the previously proposed (Asael et al., 2009) use of δ65Cu in chalcopyrite to estimate the oxidation state of fluids that transported Cu in stratiform sediment-hosted copper deposits is refined.

Changes in isotopic composition of metals enriched in hydrogen

We have studied changes in the isotopic composition of niobium and palladium as well as of titanium film structures over ceramics enriched in deuterium. We have also investigated changes in the isotopic composition of copper under thermally activated copper diffusion into nickel. An intense isotope exchange between the atoms of the matrices and impurities enriched in deuterium and changes in the isotopic composition of copper during diffusion into nickel were observed. The relationships seen in the experiments lead us to suggest that the changes in the isotope ratio may be caused (along with plausible nuclear transformations) by a strong isotopic effect involved in cold diffusion induced by hydrogen migration.

Isotopic composition of copper in serum by inductively coupled plasma mass spectrometry

The accurate, direct measurement of the 63Cu : 65Cu ratio in blood plasma or serum by inductively coupled plasma mass spectrometry is precluded by the existence of the polyatomic species ArNa+ and possibly PO2+ at mass 63. Copper in serum or plasma is largely bound to the proteins caeruloplasmin, albumin and transcuprein. Only very small amounts of copper are present in low molecular mass forms. Size-exclusion chromatography can be used to separate copper in serum from interfering sodium and phosphate ions. An accurate measurement of the 63Cu : 65Cu ratio can be made directly on the desalted protein solution.