Chromatographic Zinc Isotope Separation by Chelating Exchange Resin

Zinc isotope separations were studied by displacement chromatography using the chelating properties of malate, citrate and lactate exchange resin and EDTA as ligands. After each chromatographic operation, the heavier zinc isotopes were found to preferentially fractionated into the carboxylate complex solution phase. The separation coefficients (ε) for zinc isotope separation had the largest value and were obtained for the isotopic pairs ⁶⁸Zn/⁶⁴Zn (7.16 × 10^?4) and ⁶⁶Zn/⁶⁴Zn (3.08 × 10^?4), respectively, at 298 ± 1 K. The separation coefficient per unit mass differences (ε/ΔM) for the isotopic pair of ⁶⁸Zn/⁶⁴Zn was found to range around 1.55 × 10^?4.     

Chromatographic zinc isotope separation by phenol formaldehyde benzo crown resin

New types of phenol formaldehyde resin having benzo crown as a functional group were synthesized and applied to zinc isotope chromatographic operation. Zinc adsorption and isotope separation capacities were dramatically improved by using phenol formaldehyde benzo-15-crown-5 resin. Zinc batch adsorption tests were performed by various dehydrated organic solvents. Separation coefficient, epsilon 8.1 x 10(-4) and height equivalent to a theoretical plate (HETP) 0.105 cm for the isotopic pair of 68Zn/64Zn in phenol formaldehyde benzo-15-crown-5 resin were obtained in the case of acetone as the solvent at 298+/-1K.     

Characterization of neutron transmuted zinc traces in pure copper materials by isotope dilution mass spectrometry

The neutron transmutation doping (NTD) of highly pure copper with zinc was investigated as a promising means of achieving controlled gradation of the zinc content in the range 1–20 μg g^–1. The doping process leads to the enrichment of two stable isotopes ⁶⁴Zn and ⁶⁶Zn in a ratio which differs from that of natural isotopic distribution. Mass spectrometric investigations by thermal ionization mass spectrometry (TIMS) were performed to validate the results obtained by gamma spectrometry. The investigations included both determination of the isotopic ratios of the doped zinc isotopes and the analysis of the accumulated zinc contents by isotope dilution (ID) analysis. Thereby a sample-specific correction of the blank could be performed because the isotope ⁶⁸Zn was not influenced, because of the transmutation process. The results obtained by TIMS prove the strict proportionality of the doped zinc content, in the range 5 to 20 μg g^–1, to the neutron fluence. Comparison with gamma spectrometric results showed a very good agreement within the uncertainties.     

Rapid separation of 67,68Ga from 68Zn target using precipitation technique

The method described in this paper is a new and more capable separation (5 ppm zinc impurity) as well as fast with a 25–35 min whole process time. Optimal ⁶⁷Ga separations (yielding 93.2% efficiency) from Cu and ⁶⁸Zn were obtained by precipitate with 2 M NaOH.     

Foliar uptake of zinc by vascular plants: radiometric study

The aim of this paper was to obtain quantitative data of foliar uptake kinetics and long distance transport of zinc in tobacco (Nicotiana tabacum L.) and hop (Humulus lupulus L.) plants. Zinc was used as a model of microelement and toxic metal, tobacco and hop as a representatives of agriculturally important plants. A tip of leaf blade was immersed in the solution spiked with ⁶⁵ZnCl₂ and foliar uptake and translocation to other parts of the plant grown in nutrient solution was measured by gamma-spectrometry and autoradiography. We found that foliar zinc uptake by both plants is dependent on the initial metal concentration within the range C ₀ = 10–100 μmol dm⁻³ ZnCl₂. Zinc is immobilized mainly in immersed part of the contact leaf and only <1% is transported to non-immersed parts of the leaf. At C ₀ = 0.1 mmol dm⁻³ ZnCl₂ concentrations >2.5 mg/g Zn and 4.8 mg/g Zn (dry wt.) in immersed part of tobacco and hop leaf plant, respectively were found after 5 days of exposure. Low mobility of zinc entering the plant via the leaf surface can be attributed to the immobilization of zinc into Zn–ligand complexes with high stability constants log K at pH 6.0–8.0, such as the reaction products of Zn²⁺ ions with citric acid, histidine or phosphates. Zinc can be extracted from dried leaves by the solutions of inorganic salts, carboxylic acids, amino acids and synthetic complexing ligands such as EDTA. Anionic (SDS) and non-ionic (Tween 40) surfactants causes the decrease of the Zn foliar uptake, but not translocation of Zn from the contact leaf area. Obtained data are discussed from the point of view of possible limited efficiency of liquid formulations designed for practical applications as Zn foliar fertilizers.     

Radiochemical separation and quality assessment for the <Superscript>68</Superscript>Zn target based <Superscript>64</Superscript>Cu radioisotope production

The radiochemical separation of the different radionuclides (⁶⁴Cu, ⁶⁷Cu, ⁶⁷Ga, ⁶⁶Ga, ⁵⁶Ni, ⁵⁷Ni, ⁵⁵Co, ⁵⁶Co, ⁵⁷Co, ⁶⁵Zn, ¹⁹⁶Au) induced in the Ni supported Cu substrate — ⁶⁸Zn target system, which was bombarded with the 29.0 MeV proton beam, was performed by ion-exchange chromatography using successive isocratic and/or concentration gradient elution techniques. The overlapped gamma-ray spectrum analysis method was developed to assess the ⁶⁷Ga and ⁶⁷Cu content in the ⁶⁴Cu product and even in the post-⁶⁷Ga production ⁶⁸Zn target solution without the support of radiochemical separation. This method was used for the assessment of ⁶⁴⁺⁶⁷Cu radioisotope separation from ⁶⁷Ga, the quality control of ⁶⁴Cu product and the determination of the ⁶⁸Zn (p,2p)⁶⁷Cu reaction yield. The improvement in the targetry and the optimization of proton beam energy for the ⁶⁸Zn target based ⁶⁴Cu and ⁶⁷Ga production were proposed based on the stopping power and range of the incident proton and on the excitation functions, reaction yields and different radionuclides induced in the target system.     

Determination of zinc in plant samples by isotope dilution inductively coupled plasma mass spectrometry

Determination of zinc involved spiking with (68)Zn enriched solution, digestion by HNO(3)+H(2)O(2) in microwave decomposition unit, off-line separation of zinc on Chelex-100 column and measurement of ((64)Zn+(66)Zn)/(68)Zn isotope ratio on ICP-MS spectrometer with a quadrupole mass filter. After optimization of standard operation procedure (details are given) the method was validated. LOD was found to be 0.3 mug g(-1) for the procedure without zinc separation and 3.6 mug g(-1) for the procedure involving zinc separation, respectively. The accuracy of results was proved by analyses of several CRM and a primary solution of zinc, the concentration of which was verified by gravimetry and complexometric titration. Barium is the only element causing serious interferences and it must be removed from samples. The uncertainty budget is given together with the scheme of combined uncertainty calculation. The main uncertainty components are contamination during zinc separation and uncertainty of isotopic composition of natural zinc.     

Isotopic dilution analysis of zinc in some tissue samples of urogenital systems of rats using 65Zn

Zinc plays an important role in prostate functions. For this reason, in this study some rats have been nourished with foods containing different zinc levels and some tissue samples removed at different intervals of time from their prostate, testis, and seminal vesicle. The zinc contents of these samples have been determined using the isotopic dilution analysis technique applied with ⁶⁵Zn. In this way, the zinc contents of tissues varying between 0.02–4.50 μg Zn/g wet tissue could be determined with good precision. As a result, the zinc content of the prostate was found to be considerably high with respect to the zinc contents of the testis and the seminal vesicle. It is also interesting to note that a high zinc level in foods results in the accumulation of zinc in the prostate rather than in the testis and the seminal vesicle. The zinc content of the seminal vesicle decreases with a function of time passed from the beginning of the diet which contrasts with the case of prostate. It is also very remarkable that when the level of zinc in the body is low, the content of zinc in the testis is considerably higher.     

Complex Formation Equilibria Between Zinc(II), Nitrilo-tris(Methyl Phosphonic Acid) and Some Bio-relevant Ligands. The Kinetics and Mechanism for Zinc(II) Ion Promoted Hydrolysis of Glycine Methyl Ester

Binary and ternary complexes of zinc(II) involving nitrilo-tris(methyl phosphonic acid (H₆A) and amino acids, peptides (HL), or DNA constituents have been investigated. The stoichiometry and stability constants for the complexes formed are reported. The results show that ternary complexes are formed in a stepwise manner whereby nitrilo-tris(methylphosphonic acid) binds to zinc(II), which is then followed by coordination of an amino acid, peptide or DNA. Zinc(II) was found to form ZnA and ZnAH _n complex species where n=3, 2 or 1. The stabilities of the ternary complexes are compared with the stabilities of their corresponding binary complexes. The concentration distributions of the various complex species have been evaluated. The kinetics of the base hydrolysis of glycine methyl ester in the presence of Zn(II)-NTP complexes was studied in aqueous solution using a pH-stat technique. The pK _a for ionization of the coordinated water molecule is 9.14 as determined from the kinetic results, while direct potentiometric titration of the complex [Zn(NTP)(H₂O)] gave 9.98 (±0.02). The rate constant for the intramolecular attack of coordinated hydroxide on the ester is k=(2.65×10⁻⁴±0.003) dm³⋅mol⁻¹⋅s⁻¹.     

Zinc underpotential deposition at Pt(111) and Pt(110) under the influence of boric acid and chloride anions

Zinc underpotential deposition (Zn UPD) was studied by cyclic voltammetry in solutions of various pH and composition, where the effects of the presence of boric acid or chloride in the solution were observed. We have found that the cyclic voltammograms of Zn UPD at Pt(111) were dependent on boric acid concentrations, zinc ion concentrations, and pH in acidic solutions. These suggest that the induced adsorption of borate by releasing of H⁺ is accompanied with Zn UPD. The preadsorbed chloride species on Pt(110) accelerate the UPD process by their removal just before the UPD, making the surface sites available for the process, and the UPD remains at identical electrode potentials, while the chloride ions do not take part in the induced adsorption on UPD Zn at Pt, as clearly found by the radiotracer method. These show that the anions play versatile roles in the process of adlayer formation by their different but essential chemical characteristics. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 6, pp. 745–751 The text was submitted by the authors in English.     

Determination of activable isotopic tracers of zinc by neutron activation analysis for study of bioavailability of zinc

A procedure of pre-irradiation concentration of zinc in fecal samples using anion exchanger was developed for the study of the bioavailability of zinc by neutron activation analysis. The mass ratios between⁷⁰Zn and⁶⁸Zn, or⁶⁴Zn and their contents between natural zinc and enriched zinc are used to calculate the bioavailability of zinc when the abundance of the isotope⁷⁰Zn is not high ehough.     

Application of gas chromatography/mass spectroscopy to the investigation of metabolic pathways of trace elements using stable isotopes as tracers

Summary Zinc and copper metabolism became easier to study after science provided two research ways [1]: Isotope tracer technique and atomic absorption spectroscopy. Using stable isotopes is advantageous in humans because exposure to radioactivity is avoided and therefore the method can be used safely in infants and pregnant women. According to Ehrenkranz et al. [2, 3] zinc absorption in premature infants is 60%. Ziegler and coworkers report a lower absorption of zinc in infants (20%–44%) [8]. The copper intestinal uptake has been reported to be 68% in adults [3, 4].We have investigated the bioavailability of zinc in a group of premature infants and one term infant weighing 1850 to 5630 g and the copper absorption in a man and an adolescent with M. Wilson (a copper storage disease) and discuss the accurate isotope analysis of human feces in relation to mineral bioavailability studies of premature infants. It is shown that for the determination of bioavailability of zinc and copper, the method of chelate-gas chromatography/mass spectrometry (GC/MS) is valuable for routine application to clinical experiments; the human fecal samples resulting from diet suitably enriched with isotopes⁶⁸Zn,⁷⁰Zn or⁶⁵Cu can be routinely analysed with a precision of about 1% for these stable isotopes [2]. The total zinc in feces was determined by atomic absorption spectroscopy and the⁷⁰Zn/⁶⁴Zn ratio by chelate-GC/MS (EI). We have found different absorption values between 3% to 70% for zinc in a group of different infants including twins, triplets and preterms. The copper uptake was determined to be 79.7% and 49.9%.

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Anwendung der Gas-Chromatographie/Massenspektrometrie für die Untersuchung der Stoffwechselwege von Spurenelementen mit Hilfe von stabilen Isotopen als Tracern

     

Radio-tracer methods for studying speciation in natural waters

Radio-tracer experiments have shown that antimony, mercury and zinc interact to form complexes with humic and/or fulvic acids, whose molar masses can be estimated by gel chromatography. Sb(III) and (V) humates are stable in the pH range 7–11, but are largely dissociated below pH 4; humic acid does not reduce Sb(V) to Sb(III) in solution. Mercury forms a strong complex with humic+fulvic acids. Zinc forms complexes with both humic acids and glycine, and the humic acid complex has similar elution behaviour on dextran gel to a fraction from river water equilibrated with⁶⁵Zn. At least one other form of zinc, in addition to Zn²⁺, occurs in this river.     

Zinc(II) complexes of 4-aminoantipyrine (AAP). Crystal structure of [Zn(AAP)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>]

Zinc(II) complexes of 4-aminoantipyrine (AAP), [Zn(AAP)₂X₂] (X = Cl^–, I^–) and [Zn(AAP)(CN)₂] · 2H₂O were prepared and characterized by elemental analysis, IR and NMR (¹H & ¹³C) spectroscopy. The crystal structure of [Zn(AAP)₂Cl₂] (1) was determined by X-ray crystallography. The structural analysis of 1 shows that the complex exists as a monomeric nonionic molecule with zinc atom bound to two AAP ligands and two chloride ions adopting a distorted tetrahedral geometry. In [Zn(AAP)₂(CN)₂] · 2H₂O, the appearance of a band at 2162 cm^–1 in IR and resonances around 142 ppm in the ¹³C NMR spectra indicated the binding of cyanide to zinc(II).     

The determination of copper in zinc materials by neutron activation analysis using the 65Cu(n,γ)66Cu reaction

The nondestructive and destructive determinations of copper in zinc materials by neutron activation using ⁶⁵Cu(n,γ)⁶⁶Cu reaction are described. Observed cross-sections of ⁶⁴Zn(n,p)⁶⁴Cu and ⁶⁶Zn(n,p)⁶⁶Cu reactions for fission spectrum neutrons were 28 and 0.51 mb respectively. A double irradiation technique with one sample wrapped in cadmium foil and another bare, was employed for the correction of the concurrent formation of ⁶⁶Cu by (n,p) reaction. 100 p.p.m. of copper in zinc sulfide was determined nondestructively by γ-ray spectrometry using a thermal flux of 5 · 10¹¹ n/cm²/sec, while 0.5 p.p.m. of copper in zinc was determined by a thermal flux of 2.5 · 10¹⁰ n/cm²/sec, and by a rapid chemical separation involving copper(I) thiocyanate precipitation. The proposed activation procedures were compared with the spectrophotometric dibenzyldithiocarbamate procedure.     

Development of [<Superscript>64</Superscript>Cu]-DOTA-anti-CD20 for targeted therapy

Copper-64 was produced as a by-product of ⁵⁵Co via ⁶⁴Ni(p,n)⁶⁴Cu by 15 MeV proton bombardment of ^natNi resulting in a thick target yield of 5.31 MBq/μAh (143.5 μCi/μAh) and a radiochemical separation yield of 95% (radionuclide purity >97% after 25 hours of bombardment). Rituximab was successively labeled with [⁶⁴Cu]-CuCl₂. N-succinimidyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA-NHS) was prepared at 25 °C using DOTA and N-hydroxy succinimide (NHS) in CH₂Cl₂ followed by the addition of 1 ml of a Rituximab pharmaceutical solution. Radiolabeling was performed at 37 °C in 3 hours. Radio thin-layer chromatography showed an overall radiochemical purity of 90–95% at optimized conditions (specific activity=30 GBq/mg, labeling efficacy; 82%) using various chromatography systems. The final isotonic ⁶⁴Cu-DOTA-Rituximab complex was passed through a 0.22 μm filter and checked by gel electrophoresis for radiolysis control. Stability of the final product was checked in the formulation and in presence of human serum at 37 °C.     

Calcium and strontium,and zinc (phenazine)−· species

Calcium and strontium react with phenazine in tetrahydrofuran (THF) at ca 20 ° C to yield red solutions containing paramagnetic species based on (phenazine)⁻· (ESR characterization). Zinc reacts in THF in the presence of zinc chloride or bromide, or without metal halide in pyridine, to yield green or red ESR-active solutions also based on (phenazine)⁻·, and then, for the reaction in pyridine, a brown paramagnetic solid of composition Zn(phenazine)(pyridine)₂.     

Electrochemical properties modulation of Zinc oxide nanoparticles

The influence of zinc salts precursors (nitrate, acetate, chloride) on the electroactivity of the synthesised Zinc oxide nanoparticles (ZnONPs) was investigated using Glassy carbon ZnONPs modified electrode (ZnONPs films). The precipitation synthesised ZnONPs ‘s optical, morphological, size and Structural properties were assessed by usual spectroscopical technique. The XRD data confirmed synthesis of The ZnONPs which were predominately Zincite except for the nitrate product (zincite, ZHNH). All the NPs were of smaller size with the highest diameter size of 0.25 μM and lowest 0.066 μM for nitrate and chloride NPs respectively. All had good electroactivity, with rate constants (k_s) above 1 × 10⁻² indicating fast reversible reactions, values ranged from 0.6152 to 0.7515 for Zn(NO₃) and Zn(CH₃COO)₂ respectively. Excellent opto-electric properties were observed with the nitrate product that had the highest band gaps (∼3.7 eV), DPV current(,7.57 × 10⁻⁷ A) ΔE_p, diffusion coefficient (D_e) (3.120 × 10⁻¹(cm^2/s (Ariyanta et al., 2022) [5]) and rate constant (0.62 S^-1). In addition it had the lowest resistance as indicated by the R_s value (1.13 kΩ) below the bare electrode value lowest R_ct (444.77 kΩ) and CPE (3.00 × 10⁻⁶ F). For fabrication of sensors and batteries where low resistance and conductivity are essential, ZnONPs using Nitrate is ideal.     

Complexometric Determination of Zinc(II) Using 2,2′-Bipyridyl as Selective Masking Agent

 An indirect complexometric method is described for the determination of zinc(II) using 2,2′-bipyridyl as masking agent. Zinc(II) in a given sample solution is initially complexed with an excess of EDTA and surplus EDTA is titrated with lead nitrate solution at pH 5.0–6.0 (hexamine), using xylenol orange as indicator. An excess of 2,2′-bipyridyl is then added, the mixture shaken well and the EDTA released from the Zn-EDTA complex is titrated with standard lead nitrate solution. Results are obtained for 3–39 mg of Zn with relative errors ≤ 0.5% and standard deviations ± 0.06 mg. The interference of various ions are studied. The method is applied for the determination of zinc in its alloys and ores. Received October 27, 1998. Revision June 10, 1999.     

Preparation,characterization, and performance of a novel hollow fiber nanofiltration membrane

Nanofiltration (NF) grade hollow fiber membrane was prepared by incorporation of zinc chloride into polysulfone–polyethylene glycol (molecular weight 200) blend. A 1.0 wt% zinc chloride in the blend reduced the molecular weight cut off (MWCO) of hollow fibers from 44 kDa (average pore size 64A⁰) to a nanofiltration range of MWCO 870 Da (average pore size 7.69 A^°). MWCO decreased further to 330 Da (average pore size 4.78 A^°) on addition of 2.5 wt% zinc chloride. types of NF hollow fiber were spun, corresponding to zinc chloride concentration of 1.0, 1.5, 2.0, and 2.5 wt%. Ternary phase diagram qualitatively explained the denser morphology for various concentrations of zinc chloride. This was supported by scanning electron micrographs of cross‐section and top surface of hollow fibers. NF membranes possessed negative surface charge at extreme pH conditions. Rejection of 1000 mg/l sodium chloride solution was in between 38 to 45% at pH 11, and for divalent sodium sulfate, it was in the range of 55 to 62%. Rejection of dye congo red was found to be 100%. NF membranes showed reasonable antifouling characteristics having flux recovery ratio of more than 90% and a flux decline ratio of less than 10%. Copyright © 2015 John Wiley & Sons, Ltd.