Bismuthiol II as an analytical reagent

Summary With copper, bismuthiol II forms both cuprous and cupric complexes which are stable in mineral acids, acetic, citric and tartaric acids and the cuprous complex compared to cupric is insoluble in EDTA solution as well in organic solvents. The melting points of both cupric and cuprous complexes are respectively 148° C and 198° C. As an insoluble cupric complex copper is estimated from solutions having a maximum acidity of 0.1 N in hydrochloric or sulphuric acid and of 0.5 N in acetic acid. Even at a lower acidity, up to a p_H of about 6.2, the precipitation of copper is quantitative but at a p_H higher than 6.2 the copper complex shows an increased solubility. By the proper control of p_H and by suitable masking agents, it is possible to separate copper from almost all the ions except palladium, cadmium, lead and thallous ions.Cuprous complex, being more stable and insoluble and having practically the same tolerance to an acid solution or to a solution at a high p_H, helps towards a more complete separation of copper from all the ions stated except the thallous and bismuth.Part IX: See Z. analyt. Chem. 156, 265 (1957).     

Ion-exchange thin-layer chromatography of metal lons in organic solvent — Hydrochloric acid — Complexing agent media

Summary Thin-layers of strongly basic or strongly acidic ionexchange resins (Dowex 1 or Dowex 50), mixed with a plain cellulose, Avicel SF, have been used to investigate the chromatographic behaviour of 40 metal ions in acetic acid — hydrochloric acid — complexing agent media. The CIESE (combined ion-exchange-solvent extraction) effect, proposed by Korkisch, is noticed for scandium and thorium in the anion-exchange system involving trioctylphosphine oxide (TOPO) as the complexing agent, the system providing a basis on the specific separation of both elements. In the cation-exchange system involving TOPO, the metal ions are distributed chromatographically, so that the system allows multicomponent separations to be carried out. The system also reveals the CIESE effect for zirconium and hafnium.     

The quantitative separation of calcium from magnesium,aluminium and other elements by cation-exchange chromatography in ethanol-hydrochloric acid

Magnesium can be separated from calcium by elution with 3.0 M hydrochloric acid containing 60% ethanol from a column of AG₅₀W-X8 cation-exchange resin. Calcium is retained and can be eluted with 3.0 M hydrochloric acid or 2.0 M nitric acid. The separation factor of (α_Mg^ca=5.6 is considerably higher than that in aqueous hydrochloric acid and comparable to those obtained with organic complexing reagents. Separations are sharp and quantitative; up to 10 mmol of magnesium can be separated from 0.01 mmol of calcium and vice versa on a 60-ml column. Al, Fe(III), Mn, Ni(II), Co(II), Zn, Cd, Cu(II), Pb(II), U(VI), Be, Ga, Ti(IV) in the presence of H₂O₂ and many other elements accompany magnesium and can be separated from calcium quantitatively. Sr, Ba, Zr, Hf, Th, Sc, La and the rare earths are retained together with Ca, but can be separated by other methods.     

Paper chromatography in the separation of ions

A study has been made of the separation of ions of the alkali metals, alkaline earth metals, elements of groups IIIA and B and of anions, such as arscnate, phosphate, vanadate, molybdate, tungstate and chromate, with solvent mixtures of tert.-butyl alcohol, water and hydrochloric or acetic acid in the ratio of 7:2 1, and with 01 without tartaric, citric or malonic acid. The solvent mixture with hydrochloric acid as one of the components was found to be most effective for the separation of six cations or three anions from their mixtures. The rl and R1 values and the sequences of separations have been recorded     

The study of iron(III) and gold(III) separation by paper chromatography using diisopropyl ether

The influence of experimental conditions on the Chromatographic behavior and separation efficiency of iron(III) and gold(III) in partition paper chromatography was investigated, when solvents containing diisopropyl ether (IPE) were used. The influence of temperature (range investigated from 15 to 50 °C), initial acid concentration (1–11 M HCl), and concentration of active solvent component (0.7–7.1 M IPE, benzene as diluent) on the R_f values were particularly studied. Ascending technique using Whatman No. 1 paper was employed. Considerable influence of temperature was found. The best separation (ΔR_f = 0.26) was achieved with 9 M concentration of hydrochloric acid and 3.6 M (50% volume) concentration of IPE.     

Application of thermal analysis in the selection of polymer components used as a binder for metal injection moulding of Co–Cr–Mo alloy powder

Studies on the separation of calcium and neodymium ions by using ethylenediaminetetraacetic acid (H₄EDTA) as a complexing agent were performed. This research was undertaken due to the possibility of H₄EDTA applying to isolate rare earth elements from the solution after acidic leaching of phosphogypsum, and because of the similarity of coordination properties of calcium and lanthanides ions. The experiment was carried out in model systems containing Ca²⁺ and Nd³⁺ ions in hydrochloric or sulphuric acid. The content of calcium and neodymium metals, phase composition and thermal behaviour of the obtained products were determined by ICP-OES, FTIR, XRD and TG/DTA techniques. During the separation process, the precipitates of a light pink colour were obtained. The obtained results show that the neodymium ethylenediaminetetraacetate has been successfully formed and that the isolation of neodymium ions was more efficient in chloride medium. The precipitate included 72.2 and 3.9% of the starting amount of neodymium and calcium used in the experiment, respectively. However, in sulphates medium, these amounts were equal to 73.8 and 53.5%, respectively. Moreover, the obtained powder was polluted with sulphates. The addition of the EDTA in an excess (15%) contributed only to an increase in calcium content in the complex.

     

Anion exchange of some elements in acetic acid-hydrochloric acid medium

A comparative study of the adsorbability of Cd(II), Ni(II), Mn(II), Ga(III), La(III), Mo(VI) and bromide from aqueous acetic acid solutions on' Dowex 1-X8, 100–200 mesh, in the acetate and chloride forms, proved that chloride ions are indispensable for high adsorption from concentrated acetic acid solutions. A study of the adsorption isotherms of Ni(II), Mn(II) and Cd(II) on the acetate-form resin from acetic acid-hydrochloric acid solutions, showed that these elements form anionic complexes. The K_d values on RCl-exchanger, for a given acetic acid concentration, were highly dependent on the total exchange capacity of the resin. A simplified anion-exchange separation procedure in aqueous acetic acid was developed, with an adsorption step from a mixture of acetic and hydrochloric acids.     

Extraction of rare earth elements by primary high molecular weight amines from hydrochloric acid solutions

Extraction of trivalent lanthanides: La, Ce, Nd, Eu, Tb, Tm, Yb by primary high molecular weight amines from 0.5–3M hydrochloric acid solutions, containing complex-forming agent potassium phosphotungstate /K₁₀P₂W₁₇O₆₁/ has been investigated. The effect of hydrochloric acid, potassium phosphotungstate and amine concentration, the length of primary amine alkyl chain, organic solvents nature and elements ionic radii on distribution coefficients have been studied. It has been established that the system can be used for group isolation and separation of rare earth elements.     

Paper chromatography in the separation of ions

With a solvent mixture of acetone, hydrochloric acid and water, it is possible to have a thorough separation of ions from each other, in distinct bands, from mixtures containing to a maximum of seven ions The R_F values of the ions and the effect of temperature and concentration on the R_T and R_L values have been recorded.     

Cation Exchange Chromatographic Separation Of Lead From Mixed Solvents

Abstract

The cation exchange separation of lead from associated elements on Dowex 50W-X8, was carried out in mixed solvent systems. Elution behaviour was studied with 0.75 M HCl in the presence of various concentrations of solvents such as methanol, ethanol, 2-propanol, acetone, 1, 4 dioxane and tetrahydrofuran. Tetrahydrofuran, 1, 4 dioxane and acetone were effective in the presence of hydrochloric acid. At low concentrations of methanol, ethanol and 2-propanol in hydrochloric acid were useful for the separation of ions from lead. Lead was separated from binary and as well as multicomponent mixtures. The method was extended to the separation of lead from lead base alloys.     

Paper chromatography in the separation of ions : Separation of precious metals

A study of the separation of the precious metals. Pd⁺², Pt⁺⁴, Ir⁺⁴, Rh⁺³, Ru⁺³, Os⁺⁴ and Au⁺³, by ascending paper chromatography, using different solvents and a number of complexing agents, clearly shows that microgram amounts of the elements, when present in a mixture of five, are best separated from each other in the presence of thiourea. The Rl, Rrt values and the sequences of separation are recorded in tables to show whether a good separation of a particular mixture of ions is possible.     

Evaluation of unsymmetrical dithiodiglycolamide as novel extractant for application in selective separation of palladium(II) from aqueous solutions

A novel unsymmetrical multidentate ligand namely; N,N'-dimetyl-N,N'-didecyldithiodiglycolamide (DMD³TDGA) was synthesized and used as agent for the selective extraction of palladium(II) from hydrochloric acid solutions. A systematic investigation was carried out on the extraction of Pd(II) using DMD³TDGA. The quantitative extraction of Pd(II) with DMD³TDGA in n-dodecane is observed at ~4 M HCl. The main extracted species of Pd(II) is PdC_l2. DMD³TDGA and IR spectra of the extracted species were investigated. The extraction of palladium(II) from various concentrations of hydrochloric acid solutions in the presence of metal ions, such as Pt(IV), Rh(III), Cr(II), Ni(II), Fe(III), Nd(III), Zr(II), and Mn(II) was carried. DMD³TDGA showed very high selectivity and extractability for Pd(II). Quantitative back extraction of Pd(II) was obtained in single contact using thiourea solution. The results obtained indicated that, excellent separation of Pd(II) from the investigated metal ions can be achieved. Five successive cycles of extraction/back-extraction, indicating excellent stability and re-utilization of this new extractant can be used for selective separation of Pd(II) from other elements in hydrochloric acid medium.     

Sequential determination of Am, Cm, Pu, Np and U by extraction chromatography

Environmental contamination by artificial radionuclides and the evaluation of their sources require precise isotopic analysis and accurate determination of actinide elements above all plutonium and americium. These can be achieved by alpha spectrometry or by inductively coupled plasma mass spectrometry (ICP-MS) after chemical separation. In the present work, a simple, rapid method has been developed for the sequential separation of actinide elements from aqueous solutions and their determination by alpha spectrometry. Extraction chromatography was applied to the separation of ²⁴¹Am, ²⁴⁴Cm, ^{239 + 240,238}Pu, ²³⁷Np and ^238,235,234U using microporous polyethylene supporting tri-n-octylamine as the stationary phase and hydrochloric acid with and without reducing agents as the mobile phase. Actinide in 9 M HCl solution is introduced into the anion exchange column; Pu (IV), Np (IV) and U(VI) are retained on the column while Am (III) and Cm passed through. Pu is eluted first, reductively, after which, Np and then U are eluted. The method can be applied to all aqueous solutions which do not contain strong complexing or precipitation agents for the elements considered.     

Chromatographic separations on pyridinium tungstoarsenate-impregnated ion-exchange papers

Ion-exchange papers were prepared by impregnating chromatographic Whatman No. 3 paper with pyridinium tungstoarsenate exchanger. The composition of the material loaded on the paper shows that the compound has the formula (C₅H₅NH)₃ W_{1 2}AsO_{4 0}·R_f values of 30 metal ions were determined on these ion-exchange papers by developing with ascending technique in solvents containing mixtures of n-propanol and hydrochloric or nitric acid. Several binary, ternary and some quaternary separations were also achieved on these papers. Studies were also made on plain papers for comparison.     

Quantitative inorganic paper chromatography direct determination of nickel in microgram quantities

A method has been developed for the direct determination on filter paper of nickel, after Chromatographic separation of interfering elements. The sample is dissolved in ₃N hydrochloric acid and the solution is spotted on filter paper, together with standard solutions of nickel. After chromatographic development with a mixture of acetone, hydrochloric acid and acetylacetone, the nickel spot, which has scarcely moved, is made visible by spraying with a solution of rubeanic acid, and its reflectance is measured with a Beckman DU Spectrophotometer at 625 mμ. Most interfering elements have moved away because of their high R_F values. In the presence of large amounts of aluminiun, chromium, titanium or vanadium, a preliminary extraction of the nickel is necessary. Several technical alloys have been analyzed successfully by this method, for which only 0.045 ml of solution, containing 0.45–9 μg of nickel, are needed, although its precision is equal to that of the best colorimetric methods.     

IOn-exchange behaviour of several elements in mixed solvents

The distribution coefficients between the cation- and anion-exchangers Dowex 50 and Dowex 1, and aqueous solutions containing nitric or hydrochloric acid and organic solvents with or without amines or complexing agents, have been obtained for a number of metals including uranium, thorium, cerium, iron, copper, and nickel. The organic solvents were methanol, acetone and dimethylformamide; the amines were tributylamine and tribenzylamine, and the complexing agents EDTA and citric acid. Both batch and column methods were used.     

Solvent extraction of chromium(VI) from base metal ions with diphenyl-2-pyridylmethane as a liquid anion exchanger

The extraction of chromium(VI) from aqueous hydrochloric, nitric and sulfuric acid solutions by diphenyl-2-pyridylmethane(DPPM) dissolved in chloroform has been studied. Chromium(VI) is quantitatively extracted from hydrochloric acid solutions in the range 0.1–1M. With increasing acid concentration, the extraction of chromium diminishes and in concentrated acid solutions practically all the chromium remains in the aqueous phase. The quantitative back-extraction of chromium from the organic phase is possible with HCl or HNO₃ at concentrations higher than 5M through the use of reducing agents. The composition of the extracted chromium(VI) species was studied in solution. The complexes (DPPMH)⁺HCrO ₄ ⁻ and (DPPMH)₂Cr₂O ₇ ⁻ are extracted for tracer and macro amounts of chromium(VI) respectively. The data have been utilized for the separation of chromium(VI) from base metal ions.     

Use of organic reagents in inorganic analysis

Summary Paper chromatography of cobalt, palladium, uranium, thorium, and zirconium/1-nitroso-2-hydroxy-3-naphtholates which are quantitatively precipitated, has been studied. As most of the complexes were not soluble in organic solvents, their hydrochloric acid solutions and solution of the cobalt, palladium, and uranium complexes in ammonium hydroxide were used for spotting. A large number of developing solvents were tried both on plain and salt-impregnated papers. A solvent mixture containing 60% acetone, 38% isobutyl alcohol and 2% 12N HCl, by volume was found suitable for the resolution of a mixture of complexes of cobalt, palladium, and uranium on plain paper. Thorium and zirconium complexes, however, did not move appreciably with any of the solvent mixtures tried. The paper impregnated with salt solutions did not show any improvement in the separation. The effect of HCl in the above solvent mixture on the separation of cobalt, palladium, and uranium, was also studied. It was observed that a small amount of HCl was necessary in this developing solvent for the migration of the metals, a large excess of this acid, increases their R_f values and these are brought so close that the separation of the metals becomes difficult. The colour of the cobalt, palladium, and uranium spots on the developed chromatograms indicated that the metals migrated as their complexes. Similar experiments were done with free metals ions, which gave different R_f values and this confirmed the fact that it was the metal complexes that moved and these complexes were stable under the conditions of the experiment. Precipitation of Co, Pd and U with 1-nitroso-2-hydroxy-3-naphthoic acid is quantitative and the paper chromatographic experiment affords a convenient method of concentrating the metal ions.Part IV: See Z. anal. Chem. 155, 241 (1957).     

Cation-exchange separation of uranium in dimethylsulphoxide medium

Cation-exchange chromatography in a dimethylsulphoxide (DMSO) medium is a suitable means for separating uranium from metal ions, including copper, iron, nickel and molybdenum. Quantitative separations of uranium from 26 elements can best be effected on a column of Dowex 50W-X8 (200-400 mesh), using as the eluent a 20% v/v DMSO solution which is 0.6Min hydrochloric acid and 0.25M in sodium acetate. Only calcium is eluted with the uranium and all other elements studied are eluted either before or after uranium. The elution characteristics of uranium and of other metal ions were investigated with respect to changes in eluent and resin compositions. Separations were much less effective at higher concentrations of sodium ion or DMSO. None of the organic solvents methanol, ethanol, methyl glycol, acetone, dioxan or acetic acid was found to produce favourable separation conditions. Results with Dowex 50 resins of lower or higher cross-linkage were inferior to those obtained with the X8 resin.     

Separation of rhenium by thin-layer chromatography with polyethyleneimine cellulose in hydrochloric acid media

Summary The thin-layer chromatographic behavior of 49 inorganic ions on polyethyleneimine (PEI) cellulose has been investigated in hydrochloric acid media (0.01–1.0 mol dm⁻³). The sorption on the cellulose decreases with increasing acid concentration for most of the ions, but As(III), Ti(IV) and Te(VI) do not exhibit any R_f variation with the acid concentration. The R_f spectra of TI(I), Cd(II), Pb(II) and Zn(II) have a maximum. Ag(I), Bi(III), Nb(V), Ta(V), Mo(VI) and W(VI) are retained tightly on the layer, due to either insoluble salt formation or extensive hydrolysis. The extremely low R_f values of Hg(II), Pd(II), Au(III), Ru(III) and Pt(IV) are accounted for by stability of their chlorocomplexes. Re(VII) distributes chromatographically, having moderate R_f values between 0.3 and 0.6, so that the selective separation of Re(VII) from the other ions is feasible.