Determination of cerium in ferrous alloys

A method for the determination of cerium in ferrous alloys is described. Cerium (with lead and bismuth) is separated from other elements by anion exchange in a medium consisting of 95% methanol and 5% 5 N nitric acid; cerium alone is tlien eluted with 90% methanol-10% 6 N hydrochloric acid and determined in the eluate by titration with EDTA to xylenol orange indicator. Application of the method to several steel samples was successful.     

Neutron activation analysis of traces in electrolytic zinc sulphate solutions : Part II. determination of molybdenum and rhenium

A neutron activation analysis has been devised for the determination of traces of molybdenum and rhenium in an electrolytic zinc sulphate solution. The activities due to the daughter ^99mTc and to ¹⁸⁶Re were counted. The chemical separation was performed on an anion-exchange resin. The matrix activities were separated by elution with 0.5 N nitric acid. The separation of technetium and rhenium was performed by an elution with 0.2 N perchloric acid. To avoid errors in the molybdenum determination, the uranium present in the sample was separated before the irradiation.     

Determination of cadmium, copper and lead in natural waters after anion-exchange separtion.

A method is described for the determination of cadmium, copper and lead in samples of natural non-saline waters. After acidification with hydrobromic acid, the water sample is filtered and, following the addition of ascorbic acid, passed through a column of the strongly basic anion-exchange resin Dowex 1-X8 (bromide form). On this exchanger cadmium(II). copper(I) and lead(II) are adsorbed as anionic bromide complexes. After elution of these elements with 1 M nitric acid, the determinations by atomic absorption spectrometry are carried out in a medium consisting of 90% ($\text{v}\text{v}$) methanol and 10% ($\text{v}\text{v}$) 1.5 M hydrobromic acid. The procedure was used for the routine determination of cadmium, copper and lead in water samples collected in Austria.     

Separation of large amounts of iron(III) from cobalt,nickel, and aliminum by combined ion exchange-solvent extraction

A method is described for the cation-exchange separation of large amounts of iron(III) from cobalt, nickel, and aluminium. On the strongly acidic Dowex 50-X8, iron(III) is not adsorbed from an 80% tetrahydrofuran-20% 3 M hydrochloric acid mixture, while cobalt, nickel, and aluminium are retained; a quantitative separation is thus possible. Cobalt and nickel or aluminium are then separated by elution with 90% tetrahydrofuran-10% 6 M hydrochloric acid. In these mixtures combined ion exchange-solvent extraction appears to occur; both ion exchange and liquid-liquid extraction are. effective simultaneously.     

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.     

Ethyleneglycol-bis(aminoethyl)tetraacetic acid in the amperometric titration of cadmium in the presence of zinc

Cadmium can be titrated amperometrically with EGTA in the presence of zinc; three modifications of the titration are described. The diffusion current of cadmium may be used to follow the titration at —0.90 or —0.70 V vs, the S.C.E, in ammoniacal or acetate-buffered medium respectively The titration may also be performed in ammoniacal solution at —0.30 V vs. the S.C.E., using copper as the amperometric indicator. The influence of iron, aluminium, magnesium, alkaline earths and lead was studied. Ascorbic acid could be used to mask iron and as an effective remover of oxygen. Under appropriate conditions cadmium could be titrated in the presence of 500-fold amounts of zinc. The titration error is approximately 0.002–0.003 ml of a 0.1 M titrant solution.     

Separation of 90Y from 90Sr using sequential multiple column extraction chromatography

The distribution coefficient measurements on Y(III) and Sr(II) were performed using ditertiarybutyl dicyclohexano 18-crown-6 (Sr-selective resin) and N,N,N′,N′-tetraoctyldiglycolamide (Y-selective resin) in HNO₃, HCl and HClO₄ media. Separation factors (⁹⁰Y/⁹⁰Sr) based on distribution coefficient data suggested that perchloric acid is distinctly better medium as compared to nitric acid/hydrochloric acid. The mechanism of extraction changes with the nature and concentration of acid and is responsible for the high selectivity in perchloric acid medium. Sequential column studies were carried out on tracers (radioactive/stable) employing Sr-selective/Y-selective extraction chromatographic resins as stationary phases. The final elution of ⁹⁰Y was done in 0.01 M EDTA at pH 4.0 which can be used for clinical applications after radiochemical processing.     

Studies on the separation of 90Y from 90Sr by solvent extraction and supported liquid membrane using TODGA: role of organic diluent

Solvent extraction and supported liquid membrane transport studies on Y(III) and Sr(II) were carried out using both nitric as well as hydrochloric acid feed conditions using N,N,N′,N′-tetra-octyldiglycolamide (TODGA) in several organic diluents. The solvent extraction studies indicated extremely large separation factor (SF) values with chloroform, carbon tetrachloride, 1-decanol and hexone when 6 M HNO₃ was used as the feed. On the other hand, the SF values were 1–2 orders of magnitude lower when the nitric acid concentration was 3 M HNO₃. Significantly large SF values were also obtained from 6 M HCl when xylene, carbon tetrachloride, n-dodecane and hexone were used as the diluent. Though mass transfer was not very promising in the supported liquid membrane studies with most of the diluent systems, quantitative Y(III) transport was observed with 0.1 M TODGA in xylene with negligible Sr(II) transport suggesting possibility of obtaining carrier free ⁹⁰Y. The purity of the radiotracer was checked by half-life method.     

Tuning the diglycolamides for modifier-free minor actinide partitioning

The unsymmetrical diglycolamides (DGAs) such as N,N-dihexyl-N′,N′-dioctyl-3-oxapentane-1,5-diamide (DHDODGA), N,N-didecyl-N′,N′-dioctyl-3-oxapentane-1,5-diamide (D²DODGA), N,N-didodecyl-N′,N′-dioctyl-3-oxapentane-1,5-diamide (D³DODGA), were synthesized, and characterized by IR, NMR, and mass spectroscopic techniques. The extraction behaviour of Am(III), Eu(III), and Sr(II) by the solutions of these unsymmetrical DGAs in n-dodecane was studied as a function of concentration of nitric acid and DGA. The distribution ratio of Am(III) and Eu(III) increased with increase in the concentration of nitric acid; whereas, the distribution ratio of Sr(II) reached a maximum at 4 M nitric acid followed by decrease at higher acidities. The extraction of Am(III) and Eu(III) in 0.1 M DGA/n-dodecane decreased in the order DHDODGA > D²DODGA > D³DODGA. However, the order changed upon lowering the concentration of DGA. The third-phase formation behaviour of nitric acid and neodymium(III) in 0.1 M DGA/n-dodecane was studied as a function of concentration of nitric acid. The limiting organic concentration of nitric acid and neodymium increased with increase in the chain length of alkyl group attached to amidic nitrogen. Near stoichiometric amount of neodymium(III) was loaded in 0.1 M D³DODGA/n-dodecane without the formation of third-phase from 3 to 4 M nitric acid medium. The study revealed that the unsymmetrical diglycolamides D²DODGA and D³DODGA are superior candidates for partitioning the minor actinides from high-level liquid waste.     

镉基体中微量锌的富集与分离研究

提出了一种用于富集分离镉基体中的微量锌的分离体系,研究了从镉基体中富集分离微量锌的可行性——采用二安替比林甲烷(DAM)作为络合剂,与硫氰酸铵、锌在盐酸介质中形成三元离子缔合物,用三氯甲烷作为萃取剂,最后用氨水作为反萃剂将有机相中的锌洗脱出来与镉分离。试验发现,当15%的硫氰酸铵用量为1.5mL,DAM的用量为1.5mL,加入20mL4mol/L的盐酸时,用20mL的三氯甲烷萃取两次,10mL1:3的氨水反萃两次,锌的回收率达到95%以上,相对误差小于0.5%。     

Extraction of zinc with tri(iso-octyl)amine in methyl isobutyl ketone and colorimetric determination with zincon in the organic phase

A study was made of the extraction of zinc from hydrochloric acid solutions with solutions of methyldioctylamine and tri(iso-octyl)amine in methyl isobutyl ketone. Quantitative extraction was accomplished from 2 N hydrochloric acid with 5% (w/v) tri(iso-octyl)amine-methyl isobutyl ketone. A procedure was developed for the colorimetric determination of zinc in the organic phase after extraction using 2-carboxy-2'-hydroxy-5'-sulfoformazylbenzene (Zincon).     

Liquid Anion Exchange Studies and Separation of Mercury

Abstract

A new method is developed for the extractive separation of mercury from associated elements. Mercury is quantitatively extracted from 0.5 M acetic acid solution by aliquat 336 S, which acts as a liquid anion exchanger. The metal ion from the organic phase is stripped with sodium hydroxide solution and determined in the aqueous phase complexometrically. The extracted species is [2(R₄N⁺), Hg(OAc)₄ ^?2]. A working procedure for the selective separation of mercury from zinc, cadmium, nickel, cobalt, copper, bismuth and manganese is described.     

Fluorimetric determination of nitrate in natural waters with 3-amino-1,5-naphthalenedisulphonic acid in a flow-injection system

A rapid, sensitive and precise flow-injection method for the determination of nitrate in natural waters is presented. Nitrate is first reduced in a copperized cadmium column to nitrite, which reacts with 3-amino-1,5-naphthalenedisulphonic acid to form the azoic acid. This acid forms a fluorescent salt in alkaline medium. The injecton rate is about 30 h^?1, the relative standard deviation for 10 injections of 2 × 10^?5 M nitrate is 0.8%, and the detection limit (S/N = 3)_is 1 × 10^?8 M nitrate.     

Variations in the gross alpha and beta activity in surface waters at the Atomic Weapons Establishment Aldermaston (UK)

N,N,N′,N′-tetra-2-ethylhexyldiglycolamide (T2EHDGA) has been used for the preferential extraction of ⁹⁰Y from its mixture with ⁹⁰Sr from HNO₃ as well as HCl medium. The separation efficiencies have been found out under varying experimental conditions. The extracted species were determined from T2EHDGA concentration variation experiments carried out at 3 M nitric acid as well as HCl and were found out to be Y(X₃)₃·3(TEHDGA)_(o) for both the extraction systems, where X = NO₃ ⁻ and Cl⁻, respectively. Comparison of the T2EHDGA and TODGA based separation methods is also made. In order to avoid third phase formation, iso-decanol has been used as the modifier in all the studies. The modifier content was optimized to 30% for 4 M HCl and 20% for 6 M HNO₃ as the feed aqueous phases. Separation schemes were developed for the separation of carrier free ⁹⁰Y and the purity was checked by the half-life measurement method.     

Separation of no-carrier-added 113,117mSn and 113m,114mIn from alpha particle irradiated natural cadmium target

A natural cadmium foil was irradiated by 42 MeV α-particles to produce ^113,117mSn, ^{111,113m,114m}In simultaneously in the target matrix. After the complete decay of short lived radionuclides, long-lived NCA products were separated sequentially from the bulk cadmium by liquid–liquid extraction using di-(2-ethylhexyl)phosphoric acid (HDEHP) dissolved in cyclohexane as organic phase and HCl as aqueous phase. At the optimum condition, 10^?2 M HCl and 5 % HDEHP, NCA In along with NCA Sn radionuclides (75 %) were separated from the bulk Cd resulting to high separation factors of 2.7 × 10⁴ (D _In/D _Cd) and 500 (D _Sn/D _Cd), respectively. The NCA In was stripped back completely to the aqueous phase by 6 M HCl leaving NCA Sn in the HDEHP phase with a separation factor (D _Sn/D _In) of 3.94 × 10⁶.     

Water-soluble 2-aminomethylidene-1,3-dicarbonyl compounds as new chalcogenide colloidal stabilizers

Reactions of 2-ethoxymethylidene derivatives of 1,3-dicarbonyl compounds with N,N-dimethylethane-1,2-diamine gave a number of 2-[(2-dimethylaminoethyl)amino]methylidene-1,3-dicarbonyl compounds which were subjected to regioselective quaternization at the tertiary nitrogen atom with methyl iodide. The resulting quaternary ammonium salts inhibited aggregation of cadmium and zinc sulfide sols in aqueous medium.     

Neutron activation of traces in electrolytic zinc sulphate solutions : Simultaneous determination of mercury,uranium and ytterbium

A neutron activation determination of traces of mercury, uranium and ytterblum in electrolytic zinc sulphate solutions has been devised The isotope ¹⁹⁷Hg was measured by means of its 68-and 77-keV photopeaks Uranium was determined by measurements of the 106-keV photopeak of the ²³⁹Np daughter activity The 50- and 53-keV X-rays of ytterbium isotopes ¹⁹⁹Yb and ¹⁷⁵Yb were counted using a 1-mm thick Nal(Tl) wafer crystal The chemical separation was performed on anion-exchange resin. The matrix activities were eliminated in 185N hydrofluoric acid while the neptunium and ytterbium activities were desorbed with 5N hydrochloric acid Mercury was eluted from the column with 0.5 M thourea-0.005 N hydrochloric acid and precipitated as sulpinde     

The determination of stable scandium in plants,animals, sediments,sands, soils,rocks and minerals by neutron-activation analysis

A method is described for the determination of stable scandium in samples of plants, animals, sediments, soils, rocks and minerals. The samples and comparator standards were irradiated in a neutron flux of 5·10¹² n/cm²/sec for 4 h and dissolved and the scandium quantitatively precipitated from 2N nitric acid as scandium phytate; contaminants were rinsed from the precipitate with nitric and hydrochloric acids. The limit of detection was 0.005μg(±10% at the 95% confidence level). The activated ⁴⁶Sc was counted by γ-spectrometry.     

Determination of lead,tin, tellurium,and some doping elements in PbxSn1−xTe

A single method, based on gravimetric and polarographic analysis, has been developed to determine, in the same sample, the fundamental constituents and some doping elements in the Pb_xSn_1?xTe system. First tellurium is separated by sulfur dioxide in an acid solution (5% in HCl). This medium is suitable both for the total tellurium separation and for the subsequent tin precipitation by phenylarsonic acid. Moreover, this analytical procedure allows determination in the same sample, the concentration of some doping elements such as copper, cadmium, and zinc which are necessary to vary some physical properties of the Pb_xSn_1?xTe semiconductor system. The trace elements were determined by stripping voltammetry after tellurium, tin, and lead separation. The residual solution contains a variable amount of phenylarsonic acid which makes difficult quantitative polarographic measurements, because the electrodissolution potentials are varied and peak heights are masked. However, polarographic measurements are not altered through a wide range of phenylarsonic acid concentration if the solution is previously neutralized.     

Simultaneous Determination of Cadmium,Copper, Lead and Zinc in Amino Acid Parenteral Nutrition Solutions by Anodic Stripping Voltammetry and Sample Digestion by UV Irradiation

Abstract

Irradiation with ultraviolet (UV) energy was investigated to assay cadmium, copper, lead, and zinc by anodic stripping voltammetry (ASV) in amino acid parenteral nutrition (PN) solutions. Sample digestion by UV irradiation showed the best performances to liberate the metals from the samples (metal recoveries between 90% and 102%) in comparison with classical oxidative wet digestion methods. The best UV digestion condition was obtained with 1:10 diluted PN samples irradiated during 10 h at 90±3°C with the addition of one aliquot of 50 µL concentrated H₂SO₄ and repeated additions of 50 µL 30% (v/v) H₂O₂ at each 60 min irradiation interval. By using the UV digestion procedure cadmium, copper, lead, and zinc were simultaneously assayed in commercial amino acid PN solutions by ASV. The metal concentrations ranged between 1.3 to 4.4 for cadmium, 2.9 to 40.8 for copper, 4.4 to 16.8 for lead, and 1.4 to 208.5 for zinc. The ASV method correlated well with atomic absorption spectrometry measurements to assay the investigated analytes in amino acid PN samples after the UV digestion.