A comparative study on the separation of radiozirconium via ion-exchange and solvent extraction techniques, with particular reference to the production of 88Zr and 89Zr in proton induced reactions on yttrium

The radiochemical separation of no-carrier-added zirconium from proton irradiated yttrium was studied by two techniques, namely, ion-exchange chromatography using Dowex 50W-X8 and Dowex 21K resins, and solvent extraction using HDEHP and TPPO, the latter reagent being employed for the first time for separation of radiozirconium from bulk of yttrium. Out of all those techniques, the solvent extraction using TPPO was found to be the best: the separation yield of radiozirconium was >97%, the time of separation was short, the contamination from the long-lived ⁸⁸Y activity was low (10⁻⁴%) and the final product was obtained in the form of oxalate. The production of ⁸⁹Zr and ⁸⁸Zr of high radionuclidic and chemical purity via irradiation of yttrium targets with protons of energies 12 and 20 MeV, respectively, is described. The experimental yields of the two radionuclides were found to be 28 MBq/μA·h and 1.63 MBq/μA·h, respectively. Each value corresponds to about 80% of the respective theoretical yield.     

Anion-exchange studies of metal thiocyanates in aqueous and mixed solvent systems

The anion-exchange behaviour of metal ions in aqueous NH(4)CNS and aqueous NH(4)CNS-organic solvent mixtures has been studied. The effect of the pH and the concentrations of thiocyanate and organic solvent on the distribution coefficients has been investigated. Fifteen binary metal ion separations are reported.     

Experiences in the routine production of123I via the124Te(p, 2n)123I reaction with a low energy cyclotron

This paper deals with the results and experimental observations obtained in routine production of¹²³I via¹²⁴Te(p, 2n)¹²³I reaction, using the low energy cyclotron (protons, E_max=22 MeV) at the German Cancer Research Center in Heidelberg. The reaction was studied during the past 4 years using¹²⁴TeO₂ targets with various levels of enrichment. The purpose of the study was to determine which target material provided the highest quality and most economical production of¹²³I. A viable routine production was defined as one in which¹²³I could be conveniently and reproducably prepared in reasonable purity while maintaining a low cost for the entire process. Different methods of sublimation of¹²³I activity from the¹²⁴TeO₂ target were examined to determine the optimal conditions for recovery of radioactivity and recycling of target material. A rapid method is described which permits quantitative separation of¹²³I while allowing only a negligible loss of¹²⁴TeO₂.     

Spectrophotometric and solvent extraction studies of metal complexes of some hydrazones

Complex formation of o-hydroxybenzaldehyde isonicotinoyl-hydrazone with Co(II), Ni(II), Zn(II), Mn(II), and Cd(II) has been investigated. These complexes are soluble in water-dioxane 1:1 (v/v) solutions and they were studied spectrophotometrically. The same complexes are soluble in organic solvents and studies on their extraction with chloroform, 1-pentanol and 1-octanol, for possible analytical application, are reported. In addition, complex formation of o-hydroxybenzaldehyde benzoyl hydrazone with Zn(II), and Mn(II) is also reported.     

Anion-exchange chromatography of metal cyanide complexes with gradient separation and direct UV detection

In the regulatory analysis of water samples, cyanide content is usually expressed in various forms as free cyanide, total cyanide, weak-acid dissociable cyanide, available cyanide, and cyanide amenable to chlorination. Concentration of individual metal cyanide complex, not furnished in any of these methods, is useful in meaningful assessment of toxicity due to cyanide. In the present work, two macroporous anion-exchange columns, having high and intermediate hydrophobicity, were evaluated to achieve separation of cyano complexes of silver, iron, gold, copper, nickel, and cobalt. On the QS-Al SC column, of high hydrophobicity, the monovalent cyano complexes of silver and gold eluted last while the multivalent cyano complexes, e.g. iron and copper, eluted early. It is suggested that the retention order on this column is due to relative hydrophobicity of the metal cyanide complex, and its affect on ion exchange. In contrast, on the QS-A2 SC column of intermediate hydrophobicity, with the exception of cyano complex with Fe, the separation of the cyano complexes of five other metals closely followed an anion-exchange mechanism. Under gradient conditions, the six metal cyanide complexes were well resolved on the QS-A2 SC column and the method with direct UV detection at 215 nm was accurate (spike recovery of 99.8-118.8%) and precise (RSD of 1.0-2.6%).     

Anion-exchange behaviour and separation of metal ions on deae-cellulose in oxalic acid media

The anion-exchange behaviour of 30 metal ions on a weakly basic ion-exchanger (DEAE-cellulose) has been investigated in aqueous oxalic acid media over the concentration range 0.0010-0.50 M. There are marked differences in adsorbability between ter- and quadrivalent metal and bivalent metal groups; the system offers good prospects for group separations. The adsorptions are moderate, generally a few orders of magnitude lower than those on Dowex 1 (a strongly basic resin). Procedures for the separations Se(IV)Se(VI); As(III)As(V); multicomponent separations Mn(II)Co(II)Cu(II)Ti(IV)Zr(IV) and Cd(II)Zn(II)Cu(II), are given to demonstrate the versatility of the system.     

A theoretical approach to the solvent extraction of metal chelates

A simplified theory for the solvent extraction of metal chelates is presented. Factors which are taken into account include the metal ion, the chelating reagent, aqueous complexing agents, adduct-forming substances, the organic solvent, temperature, rates of extraction, and other effects. Equations are developed for estimating the stoichiometries and the association constants of the involved species.     

studies in the solvent extraction of some thallium(I) chelates

Studies of the extraction of thallium(I) from aqueous solution into chloroform or MIBK using 6 reagents have been made. Reagent concentration, pH variation, and the addition of adductforming agents to the organic phase have all been investigated. Association constants and distribution coefficients for several of the better reagents have been determined. Theoretical interpretations have permitted the identification, of participating species and the calculation of equilibrium constants in several cases.     

Extraction and detection of arsenicals in seaweed via accelerated solvent extraction with ion chromatographic separation and ICP-MS detection

An accelerated solvent extraction (ASE) device was evaluated as a semi-automated means of extracting arsenicals from ribbon kelp. The effect of the experimentally controllable ASE parameters (pressure, temperature, static time, and solvent composition) on the extraction efficiencies of arsenicals from seaweed was investigated. The extraction efficiencies for ribbon kelp (approximately 72.6%) using the ASE were fairly independent ¶(< 7%) of pressure, static time and particle size after 3 ASE extraction cycles. The optimum extraction conditions for the ribbon kelp were obtained by using a 3 mL ASE cell, 30/70 (w/w) MeOH/H₂O, 500 psi (1 psi = 7 KPa), ambient temperature, 1 min heat step, 1 min static step, 90% vol. flush, and a 120 s purge. Using these conditions, two other seaweed products produced extraction efficiencies of 25.6% and 50.5%. The inorganic species present in the extract represented 62.5% and 27.8% of the extracted arsenic. The speciation results indicated that both seaweed products contained 4 different arsenosugars, DMA (dimethylarsinic acid), and As(V). One seaweed product also contained As(III). Both of these seaweed products contained an arsenosugar whose molecular weight was determined to be 408 and its structure was tentatively identified using ion chromatography-electrospray ionization-mass spectrometry/mass spectrometry (IC-ESI-MS/MS).     

Extraction and detection of arsenicals in seaweed via accelerated solvent extraction with ion chromatographic separation and ICP-MS detection

An accelerated solvent extraction (ASE) device was evaluated as a semi-automated means of extracting arsenicals from ribbon kelp. The effect of the experimentally controllable ASE parameters (pressure, temperature, static time, and solvent composition) on the extraction efficiencies of arsenicals from seaweed was investigated. The extraction efficiencies for ribbon kelp (approximately 72.6%) using the ASE were fairly independent (< 7%) of pressure, static time and particle size after 3 ASE extraction cycles. The optimum extraction conditions for the ribbon kelp were obtained by using a 3 mL ASE cell, 30/70 (w/w) MeOH/H2O, 500 psi (1 psi = 7 KPa), ambient temperature, 1 min heat step, 1 min static step, 90% vol. flush, and a 120 s purge. Using these conditions, two other seaweed products produced extraction efficiencies of 25.6% and 50.5%. The inorganic species present in the extract represented 62.5% and 27.8% of the extracted arsenic. The speciation results indicated that both seaweed products contained 4 different arsenosugars, DMA (dimethylarsinic acid), and As(V). One seaweed product also contained As(III). Both of these seaweed products contained an arsenosugar whose molecular weight was determined to be 408 and its structure was tentatively identified using ion chromatography-electrospray ionization-mass spectrometry/mass spectrometry (IC-ESI-MS/MS).     

Assessment of trace metal extraction techniques with reference to aquatic sediments

Summary Different techniques have been employed to determine the extractability of non-residual metals from aquatic sediments. The methods classified as acid extractable, cold extractable and alkaline fusion extractable were compared on the basis of their efficiency in extracting metals responsible for pollution in streams and rivers in the Plateau state of Nigeria. The results show that optimum recovery of any metal depends on the choice of the decomposition procedure. While the cold extractable method showed affinity for most of the metals, copper and tin were optimally recovered by the acid digestion method. Generally, fusion methods gave scant metal recoveries which could be attributted to the low silicate content of the sample and volatilisation losses. In all cases the samples were quantitatively analysed by atomic absorption spectrophotometry and the error due to determination calculated as standard deviation.     

Anion-exchange separation of Te(IV) from Te(VI), Se(IV) and Se(VI) on deae-cellulose in mixed hydrochloric-acetic acid media

Te(IV) can be separated from Te(VI), Se(IV) and Se(VI) by adsorption of Te(IV) on a DEAE-cellulose column from a mixed 1M hydrochloric acid-acetic acid solution (1:9, v/v). This allows a selective separation of Te (IV) from the other three species in widely different mole ratios.     

Dendritic effects of crown ether-functionalized dendrimers on the solvent extraction of metal ions

The ability of a series of crown ether-functionalized dendrimers to function as alkali metal picrate extraction agents is assessed by liquid-liquid extraction and ¹H NMR titration experiments. Crown ether-functionalized dendrimers that contain Fréchet-type poly(benzyl ether) dendrons of different generation as building blocks display different extraction characteristics toward alkali metal cations. Positive and negative dendritic effects depending on the generation of the dendrimer are assigned in the complexation behaviour of the dendritic host compounds.     

表面活性剂体系萃取分离贵金属离子的研究

研究了在TritonX 100 (NH4)2SO4 络合剂体系中,贵金属离子的萃取分离行为。考察了金属络合物的液 液两相间的分配行为及影响络合物萃取行为的各种因素,优化了萃取分离条件。实验结果表明,在pH7.0～7.5的溶液中,络合剂PAR能与Pd(Ⅱ)形成稳定的络合物,可被定量萃取,实现了Pd(Ⅱ)与Pt(Ⅵ)、Ir(Ⅵ)、Mo(Ⅵ)等混合离子间的定量分离。混合离子分离中,Pd(Ⅱ)的回收率为97.5%～100.8%。     

Enhanced separation of trivalent lanthanoids by solvent extraction with 18-crown-6 and EDTA complexonate

The selectivities during solvent extraction of lanthanoids with macrocycles can be modified with complexonates in the aqueous phase. In the case of solvent extraction of lanthanoids with 18-crown-6 and trichloroacetic acid (TCA), addition of EDTA to the aqueous phase enhances the selectivities of lanthanoids by 3-7 times compared to those without the complexonate. This is due to the fact that the stability of lanthanoid-EDTA complexes increases in the opposite direction to the crown-TCA complexes across the lanthanoid series. The selectivities observed in this system are among the largest reported for the light lanthanoids. The effect of the complexonate on lanthanoid extraction can be explained by a simple model presented in this paper.     

Determination of arsenic in glass and raw materials for glass via quartz-tube hydride generation AAS after separation by solvent extraction

Summary A method is described for the determination of traces of arsenic in glass and raw materials for glass. After a digestion with hydrofluoric acid/sulphuric acid for glass and silica containing materials and varied digestion variants the arsenic is separated from the sample matrix by solvent-extraction of arsenic(III) chloride with toluene and back-extraction into water. The following determination is made by hydride generation atomic absorption spectrometry after atomisation in a heated quartz tube. A volatilization of arsenic during the digestion, different reagents for the oxidation and reduction of arsenic as well as the selectivity of the solvent extraction with regard to different interfering elements were investigated. It has been found that with the method developed, also at high concentrations of interfering elements, arsenic can be separated and a nearly interference-free determination of arsenic in glass and in raw materials for glass is possible. For example, at antimony concentrations of 60% (m/m) in the sample the detection limit is 0.5 g/g As₂O₃. The over-all detection limit is 0.05 g/g As₂O₃. The relative standard deviation is 5.7% (n=4) at a concentration of 3.6 g/g As₂O₃.