[en] Although the physiological impact of the actinide elements as nuclear toxicants has been widely investigated for half a century, a description of their interactions with biological molecules remains limited. It is however of primary importance to better assess the determinants of actinide speciation in cells and more generally in living organisms to unravel the molecular processes underlying actinide transport and deposition in tissues. The biological pathways of this family of elements in case of accidental contamination or chronic natural exposure (in the case of uranium rich soils for instance) are therefore a crucial issue of public health and of societal impact. Because of the high chemical affinity of those actinide elements for phosphate groups and the ubiquity of such chemical functions in biochemistry, phosphate derivatives are considered as probable targets of these cations. Among them, nucleotides and in particular adenosine mono- (AMP) and triphosphate (ATP) nucleotides occur in more chemical reactions than any other compounds on the earth's surface, except water, and are therefore critical target molecules. In the present study, we are interested in trans-plutonium actinide elements, in particular americium and curium that are more rarely considered in environmental and bioaccumulation studies than early actinides like uranium, neptunium and plutonium. A first step in this strategy is to work with chemical analogues like lanthanides that are not radioactive and therefore allow extended physical chemical characterization to be conducted that are difficult to perform with radioactive materials. We describe herein the interaction of lutetium(III) with adenosine AMP and ATP. With AMP and ATP, insoluble amorphous compounds have been obtained with molar ratios of 1:2 and 1:1, respectively. With an excess of ATP, with 1:2 molar ratio, a soluble complex has been obtained. A combination of spectroscopic techniques (IR, NMR, ESI-MS, EXAFS) together with quantum chemical calculations has been implemented in order to assess the lutetium coordination arrangement for the two nucleotides. In all the complexes described in the article, the lutetium cation is coordinated by the phosphate groups of the nucleotide plus additional putative water molecules with various tridimensional arrangements. With AMP 1:2 and ATP 1:1 solid-state compounds, polynuclear complexes are assumed to be obtained. In contrast, with ATP 1:2 soluble compound, the Lu coordination sphere is saturated by two ATP ligands, and this favors the formation of a mononuclear complex. In order to further interpret the EXAFS data obtained at the Lu L(III) edge, model structures have been calculated for the 1:1 and 1:2 ATP complexes. They are discussed and compared to the EXAFS best fit metrical parameters. (authors)

[en] Because of the wide range of formulations, polyurethanes (PURs) are among the most used copolymers. According to their applications, the nature and concentration of the monomers, as well as the additives, are adjusted. As copolymer, this material is difficult to characterize directly by mass spectrometry without sample pretreatment. In this work, atmospheric solid analysis probe mass spectrometry (ASAPMS) is used to characterize model and commercial PURs with different formulations. Application of a temperature gradient over the ASAP probe allows a soft vaporization of all sample components: additives are detected at lower gas temperature, whereas the polymer is detected at higher gas temperature. Thus, a temporal separation of the molecules as a function of their volatilization and/or degradation temperature is observed. The vaporized products are identified by ASAP thanks to pyrolysis, but also by low energy source fragmentation observed during the analysis. Thus, complete analysis of PURs with only a single time-of-flight (TOF) mass analyzer is realized. The ability of ASAP-MS for differentiation of different chemical structures of PURs (polyester and polyether based PURs) is demonstrated; the main advantage of this technique being that the analysis is performed in one step, directly on the crude polymer. (authors)

[en] High-precision measurements of natural variations in the stable isotopic composition of mercury show great promise as a new tracer of mercury sources and chemical transformations in the environment. We strongly suggest that all laboratories adopt a common means of data correction, standardization, and nomenclature in order to ensure that data from various laboratories can be easily evaluated and compared. We make suggestions for mass bias correction, reporting of mass-dependent and mass-independent isotope variations, and a standard protocol for reporting analytical uncertainties. We also present our measured values for isotope ratios in several mercury standard solutions. (orig.)

[en] The determination of sulfur in biologically relevant samples such as metalloproteins is described. The analytical methodology used is based on robust on-line coupling between capillary electrophoresis (CE) and octopole reaction cell inductively-coupled plasma mass spectrometry (ORC-ICP-MS). Polyatomic ions that form in the plasma and interfere with the determination of S at mass 32 are minimised by addition of xenon to the collision cell. The method has been applied to the separation and simultaneous element-specific detection of sulfur, cadmium, copper, and zinc in commercially available metallothionein preparations (MT) and metallothionein-like proteins (MLP) extracted from liver samples of bream (Abramis brama L.) caught in the river Elbe, Germany. Instrumental detection limits have been calculated according to the German standard procedure DIN 32645 for the determination of sulfur and some simultaneously measured trace elements in aqueous solution. For sulfur detection limits down to 1.3 μg L^-1 (³⁴S) and 3.2 μg L^-1 (³²S) were derived. For the other trace elements determined simultaneously detection limits ranging from 300 ng L^-1 (⁵⁸Ni) to 500 ng L^-1 (⁶⁶Zn, ⁵⁵Mn) were achieved. For quantification of sulfur and cadmium in a commercially available MT preparation under hyphenated conditions the use of external calibration is suggested. Finally, the need for proper sample-preparation technique will be discussed. (orig.)

[en] The sorption of uranium(VI) on two cationic resins containing different complexing groups, the iminodiacetic resin Chelex 100 and the weak carboxylic resin Amberlite CG-50, was investigated. The Gibbs-Donnan model was used to describe and to predict the sorption through the determination of the intrinsic complexation constants. These quantities, even though non-thermodynamic, characterize the sorption as being independent of experimental conditions. The sorption mechanism of the metal on the complexing resins was also studied by adding a competitive soluble ligand that shifts the sorption curves to higher pH values. The ligand competes with the resin for the complexation with the metal ion. Uranium is also strongly sorbed on Chelex 100 at very acid pH, through formation of two complexes in the resin phase: ML with logβ_110i=-1.16, in more acidic solution, and ML₂with log β_120i=-5.72. Only the presence of the competitive ligand in solution makes the determination of the second complex possible. Also on Amberlite CG-50 the sorption is strong and involves the formation of the complex ML ₂, in more acidic solution, with log β_120i=-3.16. In the presence of the ligand EDTA, the complex ML ₂(OH) ₂was characterized with log β_12-2i=-5.15. In all the experiments the hydrolysis reaction in the aqueous phase was quantitatively considered. (orig.)

[en] We investigated the effect of humic acid and solution pH on the uptake of the radionuclides, ⁸³Rb, ¹³⁷Cs, ⁵⁴Mn, ⁶⁵Zn, ⁸⁸Y, ¹⁰²Rh, and ⁷⁵Se in rice plants by the multitracer technique. The addition of humic acid to a culture medium containing SiO₂ increased the uptake of Mn and Zn at pH 4.3, whereas their uptake was decreased at pH 5.3. Humic acid depressed the uptake of Y at both pHs. The uptake of Se, which does not interact with humic acid, was not affected by its presence. These results suggest that uptake of the radionuclides by the rice plant is regulated by the affinity of radioactive nuclides for humic acid, as well as by the soil solution's pH. (orig.)

[en] Synchrotron FTIR can provide high spatial resolution (<10 μm pixel size) in situ biochemical analyses of intact biotissues, an area of increasing importance in the post-genomic era, as gene functions and gene networks are coming under direct scrutiny. With this technique, we can simultaneously assess multiple aspects of cell biochemistry and cytoplasmic composition. In this paper, we report the first results of our synchrotron FTIR examination of hyphae of three important fungal model systems, each with sequenced genomes and a wealth of research: Aspergillus, Neurospora, and Rhizopus. We have analyzed the FTIR maps of Aspergillus nidulans cells containing the hypA1 allele, a well-characterized single-gene temperature-sensitive morphogenetic mutation. The hypA1 cells resemble wildtype at 28 ^oC but have growth defects at 42 ^oC. We have also investigated Neurospora and Rhizopus cultures grown in media with optimal or elevated pH. Significant differences between the spectra of the three fungi are likely related to differences in composition and structure. In addition, high spatial resolution synchrotron FTIR spectroscopy provides an outstanding method for monitoring subtle subcellular changes that accompany environmental stress

[en] The risk of transmetalation reactions between gadolinium complexes used as contrast agents for magnetic resonance imaging (MRI) and iron ions is examined under physiological conditions. A fast separation of gadopentetate (Gd-DTPA) and gadoterate (Gd-DOTA) and the respective Fe transmetalation products was accomplished by high-performance liquid chromatography. For detection, the LC system was coupled to an Orbitrap electrospray ionization mass spectrometer to achieve a detection limit as low as 50 nmol/L for Fe-DTPA. In vitro experiments revealed the formation of Fe-DTPA in blood plasma samples with Gd-DTPA and Fe(III) citrate. Analysis after different incubation times of the sample showed that the exchange of the metal ions is significantly dependent on time. If this reaction takes place in the body of MRI patients, this could explain why the disease nephrogenic systemic fibrosis (NSF) develops only after a longer retention of the linear Gd complex in the patient's body. Transmetalation either with endogenous Fe(II)/Fe(III) ions or with parenteral Fe supplements with Gd-DTPA could not be proven under the applied conditions. The high stability of Gd-DOTA is responsible that transmetalation between this macrocyclic complex and neither of the Fe species was observed. These findings are important because NSF only develops after administration of Gd complexes with linear ligands. The results indicate that transmetalation reactions may be a trigger for the development of NSF, if free Fe(III) ions are accessible during a prolonged dwell time of Gd complexes with linear ligands in the patient's body. (orig.)

[en] Due to heavy metals’ magnified pollution from their accumulation in the ecosystem, practical detection of ultra-low concentration of heavy metals in environmental sample is of great significance for environmental supervision and maintenance of people’s health. Herein, a practical and sensitive assay of heavy metal mercury was developed by visually observing (or spectrum detecting) the change of cationic gold nanoparticles (AuNPs), which is directly caused by mercury ion induced hybridization between non-canonical base pairs. In this assay, signal probe’s response was direct rather than the indirect salt induction, thus avoiding the defect of salt-induced indirect response. It makes the analysis more sensitive. The results showed that the response of 8.2 × 10${}^{-<!--\; ???\; -->8}$ M Hg${}^{2+}$ could be observed with naked eye and the detection limit of Hg${}^{2+}$ in spectrometric determination was 4.9 × 10${}^{-<!--\; ???\; -->11}$ M, which is more than one order of magnitude lower than that from indirect response pattern of signal probe. In addition, high specificity of the affinity chemistry for T–Hg–T renders the assay to be highly selective. Compared with the results of cold vapor atom adsorption spectroscopy (CVAAS), this analysis has good reliability for the detection of mercury. The results fully indicate that the developed assay is an ideal alternative for online detection of heavy metal mercury in environmental pollution samples.

[en] This paper proposes the use of Anoxybacillus flavithermus SO-15 immobilized on iron oxide nanoparticles (NPs) as a novel magnetized biosorbent for the preconcentrations of uranium (U) and thorium (Th). The SPE procedure was based on biosorption of U(VI) and Th(IV) on a column of iron oxide NPs loaded with dead and dried thermophilic bacterial biomass prior to U(VI) and Th(IV) measurements by ICP-OES. The biosorbent characteristicswere explored using FT-IR, SEM, and EDX. Significant operational factors such as solution pH, volume and flow rate of the sample solution, amounts of dead bacteria and iron oxide nanoparticles, matrix interference effect, eluent type, and repeating use of the biosorbent on process yield were studied. The biosorption capacities were found as 62.7 and 56.4 mg g${}^{-<!--\; ???\; -->1}$ for U(VI) and Th(IV), respectively. The novel extraction process has been successfullyapplied to the tap, river, and lake water samples for preconcentrations of U(VI) and Th(IV).