Separation of trivalent rare earths plus sc(iii) from al,ga,in,tl, fe,ti, u and other elements by cation-exchange chromatography

A method is presented for the quantitative separation of the trivalent rare earths plus Sc(III) as a group from Al(III), Ga(III), In(III), Tl(III), Fc(III). Ti(IV), U(VI), Be(II). Mn(II), Co(II), Cu(II), Ni(II). Zn(II). and Cd(II). These elements can be eluted from a cation-exchange column with 1.75 N HCl, while the rare earth group elements are retained. Numerous other elements not investigated have low distribution coefficients in 1.75 N HCl and therefore should be separated by the same procedure; Th(IV) is retained by the column when the rare earths are elutcd with 3.0 N HCl. The only elements which partially accompany the rare earths plus Sc(III) are Zr(IV), Hf(IV), Sr(II), and Ba(II) ; these have to be separated by special procedures. The method is suitable for accurate reference analysis over a wide range of concentrations.     

Separation of nickel from other elements by cation-exchange chromatography in dimethylglyoxime/hydrochloric acid/acetone media

Nickel can be separated from Zn, Co, Cu(II), Mn(II), Fe(III), U(VI) and other elements which readily form chloro complex ions, by eluting them with 0.5 M HCl/93% acetone from AG50W-X4 resin. Nickel is then eluted selectivity with 0.5 M HCl/95% acetone containing 0.1 M dimethylglyoxime, while the alkali and alkaline-earth elements, Al, Ti(IV), Sc, Y, La, lanthanides, Zr, Hf and Th are still retained. Separations are sharp and quantitative.     

Quantitative separation of calcium from magnesium,aluminium, iron(III) and many other elements by cation-exchange chromatography in methanolic hydrochloric acid on a macroporous resin

Calcium can be separated from Mg, Al, Cu(II), Fe(III), Ga, Zn, Mn(II), Co(II), U(VI) and Ti(IV) by cation-exchange chromatography on a column of AG MP-50 macroporous resin. Sr, Ba, Sc, Y, the lanthanides, Zr, Hf and Th are retained together with calcium. The separation factor for the Ca—Mg pair in 3 M HCl containing 50% methanol is about 20 which is considerably larger than those obtained by other ion-exchange procedures. Separations with the cation-exchange resin are sharp and quantitative. A column containing only 2 g (5.4ml) of resin is sufficient to separate up to 0.2 mmol of calcium from 2 mmol of magnesium and larger amounts of Fe(III), Cu(II) and Zn. On a 10-g column, up to 2.5 mmol of calcium can be separated easily from similar and larger amounts of other elements. Distribution coefficients for calcium and magnesium with variation of cross-linkage and variation of methanol concentration are presented, together with relevant elution curves and results for synthetic mixtures.     

Quantitative separation of beryllium from magnesium,calcium, aluminium,iron and other elements by cation-exchange chromatography in nitric acid-methanol

Beryllium is separated from Mg, Ca, Mn(II), Fe(III), Al, Co(II). Zn. U(VI), La and Gd by elution with 2.0 M nitric acid in 70 % methanol from a column of AG50W-X8 sulphonated polystyrene cation exchanger, while the other elements are retained quantitatively. Sr, Ba, Sc, Y, the other lanthanides, Zr, Hf, Th, Ga, In, Cd and Ni(II) should also be separated according to their distribution coefficients or elution behaviour. Separations are sharp and recoveries quantitative from millimolar amounts down to 10 μg of beryllium. The separation of Ti(IV) and Cu(II) from beryllium is not satisfactory and requires rather large columns. Bi(III), Pb(II), Hg(II) and the alkali metals are eluted together with beryllium, but can be separated by other methods. Typical elution curves and results for the quantitative separation of binary synthetic mixtures are presented.     

Separation of lithium from sodium,beryllium and other elements by cation-exchange chromatography in nitric acid-methanol

Lithium can be separated from sodium, beryllium and many other elements by eluting lithium with 1 M nitric acid in 80% methanol from a column of AG50W-X8 sulphonated polystyrene cation-exchange resin. The separation factor is not quite as large as that in 1 M hydrochloric acid in 80% methanol, but many elements, such as Zn, Cd, In, Pb(II), Bi(III) and Fe(III), which form chloride complexes in 1 M HCl-80% methanol are retained quantitatively together with Na, Be, Mg, Ca, Mn(II), Al, Ti(IV), U(VI), and many other elements, when 1 M HNO3-80% methanol is used for elution of lithium. A method for the accurate determination of traces of lithium in rock samples is described, and some results obtained are presented together with relevant distribution coefficients, elution curves and results for the analysis of synthetic mixtures.     

Quantitative separation of lanthanides and scandium from barium,strontium and other elements by cation-exchange chromatography in nitric acid

The lanthanides plus yttrium and scandium are separated from Ba, Sr, Ca, Mg, Pb(II), Bi(III), Zn, Mn(II) and U(VI) by eluting these elements with 2.0 M nitric acid from a column of AG50W-X8 cation exchange resin (200-400 mesh). The lanthanides are retained and can then be eluted with 4 M nitric or hydrochloric acid. Separations are quantitative and applicable to microgram and millimolar amounts of the lanthanides and the other elements. Elements such as Cu(II), Co(II), Ni(II), Cd. Hg(II), T1(I). Ag, Be, Ti(IV) and the alkali metals should accompany barium quantitatively according to their known distribution coefficients. Relevant elution curves and results of analysis of synthetic mixtures are presented.     

Selective separation of uranium from other elements by cation-exchange chromatography in hydrobromic acid and hydrochloric acid-acetone mixtures

U(VI) can be separated from Ga, Fe(III), Bi, Pb, Cd, Zn, Cu(II) and Au(III) by quantitative elution with 0.50M HBr in 86% acetone or with 0.35M HBr in 90% acetone from a column of AG50W-X4 cation-exchange resin of 200-400 mesh particle size. U(VI) and many other ions are retained. U(VI) then can be eluted selectively with 0.50M HCl in 83% acetone or with 0.35M HCl in 85% acetone. Co(II), Mn(II), Mg, Ca, Ti(IV), Al, Zr, Th and La are quantitatively retained by the column. These elements then can be eluted with 5M HNO(3). At the higher acid concentration (0.50M) the separation between U(VI) and Li is not satisfactory but is excellent at the lower acid concentration; the U(VI) peak is sharper at the higher acid concentration. Separations are sharp and quantitative, as is demonstrated by results for some synthetic mixtures. Distribution coefficients and elution curves are presented.     

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.     

Quantitative separation of gold from cadmium, indium, zinc and other elements by cation-exchange chromatography in hydrochloric acid-acetone medium

Gold(III) can be separated from Cd, In. Zn, Ni, Cu(II), Mn(II), Co(II), Mg, Ca, Al, Fe(III), Ga and U(VI) by adsorbing these elements on a column of AG50W-X8 sulphonated polystyrene cation-exchange resin from 0.1M HCl containing 60% v v acetone, while Au(III) passes through and can be eluted with the same reagent. Separations are sharp and quantitative. The amounts of gold retained by the resin are between 1 and 2 orders of magnitude lower than encountered during adsorption from aqueous 0.1M HCl. Recoveries for mg amounts of gold are 99.9% or better and for ng amounts are still better than 99%, as shown by radioactive tracer methods. Hg(II), Bi, Sn(IV), the platinum metals and some elements which tend to form oxy-anions in dilute acid accompany gold. All other elements, though not investigated in detail, should be retained, according to their known distribution coefficients. Relevant elution curves, results of quantitative separations of binary mixtures and of recovery tests are presented.     

Determination of aluminium, scandium and rare earth elements by emission flame spectrometry

Summary Emission spectrometry in nitrous oxide-acetylene flames in combination with a highly resolving double monochromator and sensitive detecting system enables simple, sensitive and selective determinations of aluminium, scandium and all rare earth elements with exception of cerium in complicated matrices. Calibration plots are linear for a large concentration interval ( 100 g·ml^–1), detection limits are in ng · ml^–1 level and RSD does not exceed 3% on the optimal concentration level of the particular element. The determination of Al, Sc, Eu and Yb showed particular advantages as to methods using ICP-spectrometry.

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Bestimmung von Aluminium, Scandium und Seltenen Erden durch Emissions-Flammenspektrometrie

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

Separation of titanium and uranium from other elements by tannin

Summary Titanium and uranium have been precipitated by tannin in the presence of various other ions, e.g., Fe³⁺, Al³⁺, Cr³⁺, Th⁴⁺, Zr⁴⁺, Bi³⁺, Pb²⁺, (VO)²⁺ and rare earths, which are kept in solution by EDTA. The precipitation was carried out by raising the p_H of the acidic solution containing EDTA and tannin by dilute ammonium hydroxide or hexamine. The p_H of complete precipitation of titanium is 4.0 and above and that of uranium is 6.0 and above.

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Zusammenfassung Titan und Uran werden mit Tannin in Gegenwart verschiedener Fremdionen, die durch ÄDTA in Lösung gehalten werden, gefällt (z.B. in Gegenwart von Fe³⁺, Al³⁺, Cr³⁺, Th⁴⁺, Zr⁴⁺, Bi³⁺, Pb²⁺, (VO)²⁺, Seltenen Erden). Die Fällung wird durchgeführt, indem man die saure Lösung, die ÄDTA und Tannin enthält, mit Ammoniak oder Hexamethylentetramin neutralisiert. Titan wird bei p_H-Werten über 4,0 und Uran bei solchen über 6,0 vollständig ausgefällt.

     

Quantitative separation of gallium from zinc, copper, indium, iron(III) and other elements by cation-exchange chromatography in hydrobromic acid-acetone medium

Gallium can be separated from Zn, Cu(II), In, Cd, Pb(II), Bi(III), Au(III), Pt(IV), Pd(II), Tl(III), Sn(IV) and Fe(III) by elution of these elements with 0.50M hydrobromic acid in 80% acetone medium, from a column of AG50W-X4 cation-exchange resin. Gallium is retained and can be eluted with 3M hydrochloric acid. Separations are sharp and quantitative except for iron(III) which shows extensive tailing. With 0.20M hydrobromic acid in 80% acetone as eluting agent, all the species above except iron(III) and copper(II) can be separated from gallium with very large separation factors. Only a 1-g resin column and small elution volumes are required to separate trace amounts and up to 0.5 mmole of gallium from more than 1 g of zinc or the other elements. Hg(II), Rh(III), Ir(IV), Se(IV), Ge(IV), As(III) and Sb(III) have not been investigated, but should be separated together with zinc according to their known distribution coefficients. Relevant elution curves, results for the analysis of synthetic mixtures and for amounts of some elements remaining in the gallium fraction are presented.     

Separation of trace amounts of indium, gallium and aluminium from each other by cation-exchange chromatography on AG50-X4 resin

Traces and minor amounts of indium, gallium and aluminium can be separated from gram amounts of thallium and from each other by cation-exchange chromatography on a column containing as little as 2 g of AG50W-X4, a cation-exchange resin with low cross-linking. An elution sequence of 0.1 M HBr in 40% acetone [for Tl(III)], 0.2M HBr in 80% acetone for In, 0.3M HCl in 90% acetone for Ga and 3M aqueous HCl for Al is used. The separations are very sharp and even 10-mug amounts of In, Ga and Al in synthetic mixtures are recovered quantitatively, with a standard deviation of 0.3 mug. The separation factors between neighbouring ions are extremely large (> 5000).     

Separation of alkaline earth elements by cation-exchange chromatography in ammonium malonate media

Be(II), Mg(II), Ca(II), Sr(II) and Ba(II) can be separated by elution from a cation-exchange column in the ammonium form with increasing concentrations of ammonium malonate. A typical elution sequence for a 60-ml column (volume in H⁺-form) of AG₅₀-X8 resin is: 200 ml of 0.20 N ammonium malonate plus 0.10 N malonic acid for Be(II); 300 ml of 0.50 N, 450 ml of 0.70 N, 350 ml of 1.10 N ammonium malonate for Mg(II), Ca(II) and Sr(II), respectively, and 200 ml of 3.0 N nitric acid for Ba(II). Separations are sharp and quantitative for element pairs in weight ratios from 1:1000 to 1000:1. Distribution coefficients, elution curves and quantitative separations are presented.     

Determination of light rare earths and other elements in Cuban soils

The objective of the present study was the elaboration of a procedure for the determination of Y, La, Ce, Pr and Nd in soils by spectrophotometry with Arsenazo III preceded by a separation-concentration stage, which includes coprecipitation and ion exchange. Multielement analysis by energy dispersive X-ray fluorescence (including Y, La, Ce and Nd) and flame atomic absorption spectrophotometry was carried out simultaneously in order to obtain a general characterization of the soil samples. Certified reference materials and statistical intercomparison of the obtained results were used to evaluate the accuracy of the methods. The precision was examined by analyzing replicate samples.     

Determination of yttrium, scandium and other rare earth elements in uranium-rich geological materials by ICP-AES

A rapid method is described for the determination of yttrium, scandium, and other rare earth elements (REEs) in uranium-rich geological samples (containing more than 0.1% U) and in pitch blende type of samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) after separation of uranium by selective precipitation of the analytes as hydroxides using H(2)O(2)/NaOH in the presence of iron as carrier. Uranium goes into solution as soluble peruranate complex. The precipitated rare earth hydroxides (including Y and Sc) are filtered and dissolved in hydrochloric acid prior to their aspiration into plasma for their individual estimation after selecting interference free REE emission lines. The method has also been applied to some international reference standards like SY-2 and SY-3 (by doping a known amount of uranium) along with one in-house pitch blende sample and the REE values were found to be in agreement with the most usable values, offering an R.S.D. of 1-8.8% for all the REEs', Y and Sc. The method compared well, with the well- established cation exchange separation procedure.     

Separation of selenite,sulkate and iron by cation-exchange resin

Selenite, sulfate and iron(III) are separated by cation-exchange resin. Microgram amounts of selenite in iron(III) sulfate solution at pH 2 are completely adsorbed on the resin together with the large excess of iron(III). while sulfate passes through. Selenite is eluted with 0.5 N hydrochloric acid, leaving iron(III) in the resin. The procedure is applied to the determination of these elements in natural iron sulfides.     

Separation of copper(II) from uranium(VI) and many other elements by cation-exchange chromatography in acetone-hydrobromic acid media: Improved selective separation of copper

Co(II), Ni(II), Mn(II), Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ti(IV), V(IV), Zr, Hf, Th, Al, Sc, Y, La, the lanthanides and also U(VI), which accompany copper(II) in hydrochloric acid-acetone mixtures, can be separated from copper by eluting copper(II) with 0.50 M hydrobromic acid in 85% acetone from a column of AG 50W-X8 resin, 200–400 mesh, while all these elements are retained by the column quantitatively. Separations are sharp and quantitative, as is demonstrated by results for some synthetic mixtures. Some relevant elution curves are presented.     

Selective separation of indium from zinc, lead, gallium and many other elements by cation-exchange chromatography in hydrohalic acid-acetone medium

Indium can be separated from Zn, Pb(II), Ga, Ca, Be, Mg, Ti(IV), Mn(II), Fe(III), Al, U(VI), Na, Ni(II) and Co(II) by selective elution with 0.50M hydrochloric acid in 30% aqueous acetone from a column of AG50W-X8 cation-exchange resin, all the other elements being retained by the column. Lithium is included in the elements retained by the column when 0.35M hydrochloric acid in 45% aqueous acetone is used for eluting indium, but the elution of indium is slightly retarded. Ba, Sr, Zr, Hf, Th, Sc, Y, La and the lanthanides, Rb and Cs should also be retained according to their distribution coefficients. Cd, Bi(III), Au(III), Pt(IV), Pd(II), Rh(III), Mo(VI) and W(VI) can be eluted with 0.20M hydrobromic acid in 50% aqueous acetone before the elution of indium, and Ir(III), Ir(IV), As(III), As(V), Se(IV), Tl(III), Hg(II), Ge(IV), Sb(III) and Sb(V), though not investigated in detail, should accompany these elements. Relevant distribution coefficients and elution curves and results for analyses of synthetic mixtures of indium with other elements are presented.