地质样品铁同位素自动固相萃取系统研究

研发了一种自动固相萃取系统,用于分离地质样品中铁同位素。系统有4个并行通道,可以一次处理4个样品。对于这4个样品,一次处理过程仅需24 min。选用AG1-X8阴离子交换树脂对花岗岩样品(GBW07103)中的铁进行萃取。在萃取过程中,当盐酸浓度大于6 mol/L时,铁形成络阴离子并被吸附在AG1-X8阴离子交换树脂上,其余阳离子被洗脱出来。用浓度为8 mol/L的HNO 3和H 2O洗脱铁,铁的洗脱体积为4 mL,铁可以被定量回收,回收率达到96.0%~107%。消除了测试过程中的基体影响,提高了样品处理效率,减少了人为污染风险,是一个多元化样品处理工具。     

Separation of traces of manganese,cobalt, nickel and copper from gram amounts of tellurium by cation-exchange chromatography in hydrochloric acid/acetone media

Traces of Mn(II), Co(II), and Ni(II) and minor amounts (up to 20 mg of these elements are separated from gram amounts of tellurium by cation-exchange chromatography on small columns (3 g) of macroporous AG MP-50 resin or larger colunns (5 g) of microporous AG 50W-X8 resin. The trace elements are retained from 0.5 M HCl containing 70% acetone while tellurium passes through and is eluted completely with this solution. The trace elements are then eluted with 3.0 M HCl and can be determined by atomic absorption spectrometry. Copper (II) can also be separated but requires a 10-g column of AG MP-50 resin. Separations are sharp and quantitative and only microgram amounts of tellurium remain in the trace element fraction when a 3-g sample of tellurium dioxide is taken; 10-μg amounts of the trace elements were separated from such samples and determined with standard deviations of <1%. Relevant elution curves and results for the analysis of synthetic mixtures are presented.     

Spectrophotometric determination of micro amounts of molybdenum and vanadium by reduction of iron(III) in the presence of ferrozine

Molybdenum and vanadium, in the range 0.1-1 ppm have been determined with a relative precision of 1-2% with iron(III) in the presence of Ferrozine. The separation of molybdenum and vanadium from interfering elements has been achieved by ion-exchange with either cation-exchange RG 50 followed by anion exchanger AG 1-X8, or the exchange-resin NBL 17.     

Separation of uranium from uraniferous coaly clays using a selective ion-exchange two-step elution system

Summary An ion-exchange process for the selective separation and enrichment of uranium from the main elements Si, Al, Fe, Ca, Mg, Na, K as well as from Mo and V, which are present in uraniferous coaly clays, has been developed. After a selective carbonate leaching of the roasted ore, a 0.5 mol/l Na₂CO₃/0.5 mol/l NaHCO₃ solution was passed through the macroporous ion-exchanger AG MP-1, which at pH10 absorbed uranium quantitatively in form of a carbonato complex. Remaining absorbed amounts of Mo and V were eluted with 0.1 mol/l EDTA in 0.5 mol/l Na₂CO₃/0.5 mol/l NaHCO₃, while U was quantitatively separated by a second elution step with 0.5 mol/l HNO₃ and was afterwards precipitated with NH₄OH as a high-grade yellow cake. Differential pulse polarography (DPP), atomic absorption spectroscopy (AAS), X-ray fluorescence (XRF), instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS) had been used to determine the uranium content in the raw materials and to investigate the effectivity of the different steps of the developed process.     

Improved processes of molybdenum-99 production

Two improved processes of⁹⁹Mo production have been developed on laboratory scale. The first one allows to purify Mo of natural isotopic composition from tungsten impurities from 64 to <10 ppm by using preferential adsorption of tungsten on hydrated tin(IV) oxide (SnO₂ nH₂O) before irradiation in a nuclear reactor. The second process deals with the separation of pure fission product⁹⁹Mo from²³⁵U irradiated in a reactor. Two versions of separation process for production of fission⁹⁹Mo have been developed. Both versions start with the dissolution of²³⁵U oxide target in nitric acid and are based on sequential use of alumina and anion exchange resin AG® 1-X8 columns. The yield of⁹⁹Mo in both versions is 80–89%.     

Distribution coefficients and ion-exchange selectivities for 46 elements with a macroporous cation-exchange resin in hydrochloric acid-acetone medium

Distribution coefficients with the macroporous cation-exchange resin AG MP-50 in HCl-acetone mixtures ranging from 0.2 to 4.0M HCl and from 0 to 95% acetone have been determined for 46 elements. The ion-exchange behaviour of the elements is discussed, some possible separations are indicated, and elution curves demonstrating separations of the combinations Au(III)BiZnPbSr; Rh(III)InGaCuNi and CdFe(III)LiAlYb are presented.     

Improved separation of cadmium-109 from silver cyclotron targets by anion-exchange chromatography in nitric acid—hydrobromic acid mixtures

A method is presented for improved separation of ¹⁰⁹Cd from silver cyclotron targets. After dissolution of the target material in nitric acid and removal of silver by precipitation with copper metal, at pH 5, the cadmium is separated from zinc, copper and other elements by anion exchange chromatography. The solution in 0.5 M nitric acid plus 0.1 M hydrobromic acid is percolated through a column containing 4 ml of AG1-X8 anion-exchange resin (100–200 mesh), equilibrated with the same acid mixture. Zinc, copper(II) and other elements are eluted with 50 ml of this mixture. Cadmium is retained and finally eluted with 50 ml of 3 M nitric acid. The cadmium is retained much more strongly from the hydrobromic acid mixture than from the 0.02 M hydrochloric acid used for such separations previously; the presence of the strongly absorbed nitrate anion in fairly high concentration completely eliminates the tailing of zinc observed in 0.02 M hydrochloric acid. A typical elution curve and results of quantitative separations are presented.     

Quantitative separation of the alkali metals by cation-exchange chkomatography with bio-rex 40 resin : Application to silicate analysis

The application of BIO-REX 40, a phenolformaldehyde resin, to the quantitative separation of Li, Na, K, Rb and Cs is described. All five elements can be separated in a single procedure by using a 25-g (62-ml) resin column and eluting lithium with 500 ml of 1.00 M hydrochloric acid in 80% ethanol, sodium with 500 ml of 0.20 M hydrochloric acid, potassium with 250 ml of 0.70 M hydrochloric acid, rubidium with another 450 ml of 0.70 M hydrochloric acid and cesium with 500 ml of 4.0 M hydrochloric acid. Procedures are described for the accurate determination of alkali metals in silicate minerals, plant material and water. Al, Fe, Ti, Zr, V, Mo and some other elements are first separated by absorption as oxalato complexes on a column of AG1-X8 resin. The alkali metals are finally determined by gravimetry or atomic absorption spectrometry. Tables of distribution coefficients and quantitative results of analyses of synthetic mixture and standard silicate samples are presented together with typical elution curves.     

A straightforward protocol for Hf purification by single step anion-exchange chromatography and isotopic analysis by MC-ICP-MS applied to geological reference materials and zircon standards

A straightforward one-step Hf purification protocol for geological samples using common anion-exchange chromatography and isotopic measurements by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is described in this paper. The sample is dissolved in concentrated HF–HNO₃ mixtures with round-bottom Savillex? Teflon screw-top capsules or high-pressure stainless steel jacketed Teflon bombs. After complete dissolution, the chemical separation between Hf and isobarically interfering elements such as Lu, Yb, and matrix elements like Ti, is performed and achieved simultaneously using a common one-step anion exchange resin (AG1-X8). The Hf yields are >90% and total procedural blanks are lower than 20 pg. This protocol not only avoids using multiple-stage ion exchange resins, but also eliminates perchloric acid to break down fluorides after HF treatment of the sample. In addition to whole rock, this protocol is also practical for zircon and baddeleyite Hf purification prior to isotopic measurement. New Hf isotopic data for zircon 91500, Temora, CN92-1 and FM0411, together with Phalaborwa baddeleyite are presented for this method. Multiple analyses of the international geological reference materials and standard zircon and baddeleyite used in U–Pb geochronology demonstrate that this method is simple, economic, efficient and reproducible.     

Cyclotron production of 68Ge with a Ga2O target

Systematic information of exchange behavior of Ge(IV) and Ga(III) in varying oxalic acid (0.05M and 0.25M) and sulphuric acid (0.005M-2M range) mixtures is presented. These findings were used to develop a separation involving ⁶⁸Ge from a Ga₂O target material. A method based on acid dissolution of the target and chromatography on an anion exchange resin (Bio-Rad^Ò AG1-X8) was developed. The separated ⁶⁸Ge has high radionuclidic purity and an acceptable chemical purity.     

Separation of vanillylmandelic (VMA) and homovanillic (HVA) acids from urine for assay by a two resin column system

A procedure is described for separating vanillylmandelic acid (VMA) and homovanillic acid (HVA) from urine so that they can be assayed by chemical means or gas chromatography. The process comprises passing a threefold diluted urine over cation exchange column (AG 50W-X12) to remove catecol amines and amino acids. The VMA and HVA is then adsorbed from the diluted urine to an anion exchange column (AG 2-X8). After washing with water, the HVA and VMA are eluted with an NaCl-K₂CO₃ solution. The VMA can be determined by oxidation to vanillin directly. By extraction with n-pentanone-2, after acidification and evaporation to dryness, the residue may be redissolved for processing or treated with a methylating reagent for gas chromatography. For the latter purpose, 4-methoxy benzophenone is recommended as the internal standard.     

Distribution coefficients and cation-exchange behaviour of 45 elements with a macroporous resin in hydrochloric acid/methanol mixtures

Cation-exchange distribution coefficients are presented for 45 elements with the macroreticular (macroporous) cation-exchange resin AG MP-50 in mixed hydrochloric acid/methanol media, with acid concentrations ranging from 0.5 to 6.0 M, and methanol concentrations from 0 to 90%. The ion-exchange behaviour of the elements is discussed, some possible separations are indicated, and 3 multi-element elution curves are presented, demonstrating the separations of the combinations In-Zn-Ga-Al-Yb; Cd-Li-Cu(II)-Mg-Ca; and Pt(IV)-Te(IV)-V(IV)-Fe(III)-Mn(II).     

Removal of185W,99Mo and125Sb radioisotopes from aqueous solutions using polyamine incorporated polysaccharides

Polyamino group-containing resins act both as chelating ion exchangers and weakly basic anion exchangers depending upon the species in contact in the solution. In the present work, ion exchangers based on polyamine incorporated polysaccharides (cellulose and galactomannan or guaran) have been used for removal of radioisotopes of¹⁸⁵W as WO ₄ ^2– ,⁹⁹Mo as MoO ₄ ^2– and¹²⁵Sb as Sb³⁺ from their separate aqueous solutions. These chelating anion exchangers have been synthesized by reaction of polysaccharides with epichlorohydrin followed by the respective polyamines as nucleophiles in a strongly alkaline medium. WO ₄ ^2– and MoO ₄ ^2– are adsorbed from their aqueous solutions through anion exchange process by chloride form of cellulose-triethylenetetraamine (cellulose-trien), cellulose-tetraethylenepentaamine (cellulose-tetren), guaran-triethylenetetraamine (guar-trien) and guar-tetraethylenepentaamine (guar-tetren) weakly basic anion exchangers. Guar-tetren chelating polymer has been found to be highly selective for¹²⁵Sb isotopes presumably due to the presence of chelating cis-hydroxy and tetren groups in the galactomannan matrix.     

Separation of 103Pd from Rh and Ag by the macroporous AG MP-1 anion exchange resin in Ag targets

A radiochemical process is reported for the production of ¹⁰³Pd from Ag targets for use in brachytherapy. The procedure, which is based on anion exchange chromatography, separates Pd from a large amount of target material (16 g Ag), as well as Rh radioisotopes (mainly ¹⁰¹Rh and ¹⁰⁰Rh), which are produced from decays of their Pd parents. The AG MP-1 anion exchange resin was used for the process. For elution of Rh and Ag, 3M nitric acid solution was used and 5% ammonia solution was used to elute the Pd. The average recovery of Pd was 97.4%. An elution curve for Pd was set up and a panel for the radiochemistry designed and installed in a hot cell.     

Chromatographic and electrophoretic behaviour of primary aromatic amines on anion-exchange thin layers

The use of polystyrene-based anion exchangers with aqueous eluents for the separation of primary aromatic amines has been investigated, and extended with satisfactory results to microcrystalline cellulose, cellulose-based anion-exchangers and sodium CM-cellulose layers.Interesting separations of the amines have also been effected electrophoretically on AG 1-X4 layers.The use of water-organic solvent mixtures on polystyrene-based cation exchangers is discussed.     

Analysis of trace actinide elements in soil organic matter: Optimization of sample processing to improve chemical separation of U and Pu

Chemical separation yield of actinide elements from soil samples containing high amounts of organic matters was often low as compared to that for samples containing low organic matters. We compared chemical yield of uranium and plutonium from organic-rich Japanese soil and humic acid samples which were subjected to three different pretreatment procedures ((1) pulverization only, (2) dry-ashing at 510 °C after pulverization, and (3) 680 kGy gamma-ray irradiation after pulverization) prior to acid digestion. Separation of U and Pu was performed by U-TEVA resin and AG1-X8 anion exchange resin, respectively. For organic samples, pretreatment procedures governed the yield of actinide elements significantly. Chemical separation yield of U was low (6±1%) for Aldrich humic acid sample after dry-ashing at 510 °C. For such samples, gamma-ray irradiation improved the yield of U to 35±22%. Recovery of Pu was lower for some organic soil samples which were dry-ashed at 510 °C (27±2%) as compared to those which were not dry-ashed (62±10%).     

Recovery of <Superscript>65</Superscript>Zn from waste solutions from gallium targets at Brookhaven Linac Isotope Producer

A procedure for recovery of ⁶⁵Zn from acidic Ga-rich solutions generated in ⁶⁸Ge production process was developed and implemented in a “hot cell” environment. A one step simple separation was carried out on anion exchange column filled with Biorad AG1-X8 resin. With ⁶⁵Zn recovery yields of more than 95% this procedure is currently routinely used at Brookhaven Linac Isotope Producer.     

Determination of weight distribution ratios of Pa(V) and Np(V) with some extraction chromatography resins and the AG1-X8 resin

Literature data on distribution ratios (D_w) of Np(V) and Pa(V) for the AG1-X8 resin are scarce whereas those related on resin capacity factors (k′) values for TEVA, TRU and U/TEVA resins are absent. Therefore, batch extraction experiments for Pa(V) and Np(V) from HCl and HNO₃ media were realized, at tracer scale, with AG1-X8 and EIChroM resins (TEVA, TRU and U/TEVA). Based on the new D_w and k′ values obtained in this study, a new protocol for Pa/Np separation has been developed leading to a better separation factor of 10⁵ and a chemical yield of 97 ± 3% and 99 ± 1% for Pa and Np, respectively. A separation of ²³¹Pa from uranium matrix was successfully tested.     

Kathodenstrahlpolarographische Bestimmung von Spurenelementen in Tetrachlorogolds?ure nach ionenaustausch-chromatographischer Trennung

Zusammenfassung Die kathodenstrahlpolarographische Bestimmung von Ni, Pb, Cu, Co, Fe, Mo, Te, Sn, Zn, Bi, Cd, Tl in Tetrachlorogoldsäure wird beschrieben. Die Nachweisgrenzen liegen im 10^–4%- bzw. 10^–5%-Bereich (Ni, Co, Mo). Die Spuren werden über einen Ionenaustauscher AG 1X8 untereinander und von der Matrix getrennt.

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Cathode-ray polarographic determination of trace elements in tetrachloroauric acid after separation by ion exchange

A method is described for the cathode-ray polarographic determination of traces of Ni, Pb, Cu, Co, Fe, Mo, Te, Sn, Zn, Bi, Cd, Tl in H(AuCl₄). Gold is separated from the trace metals by absorption on the strongly basic anion-exchange resin AG 1X8. The detection limits are within the ranges of 10^–4% and 10^–5% ((Ni, Co, Mo).

     

Direct spectrographic determination of impurities in uranium tetrafluoride

A direct spectrographic method for tlic determination of some impurities in UF₄ is described. The sample in the graphite electrode was covered with a layer of alumina before the arc was struck; alumina prevents the volatilization of UF₄ and thus avoids high spectral and background interferences. To stabilize the discharge, a controlled atmosphere of argon and oxygen was used. The impurity elements were divided into 3 categories according to their volatility: high (B, Si), medium (Co, Mn, V, Mo, Ti, etc.), and low (Ni, Pb, alkaline earths, etc.). Impurities of high and medium volatility could be determined with germanium or aluminum as internal standard. The sensitivities found for this method generally agreed with those of the carrier distillation method. The coefficients of variation varied from 8 to 25% at the 25 p.p.m. level.