Abtrennung und radiochemische Bestimmung geringer Mengen Seltener Erden in extraterrestrischem Material

The detection limits in neutron activation analysis are up to the standards of extraterrestrical matter analysis. Instrumental analysis is possible only after a group separation of the rare earth elements. The measurements requires a 26 day decay period. If results are desired within a shorter time interval the individual rare earth elements have to be separated. Gas chromatography and electrophoresis were applied in this work. Gas chromatography of metal chelates using radioactive reagents with high specific activity significantly improves the detection limits. The gas-chromatographic separations, however, should be only regarded as model experiments. The experimental results were obtained much faster (within 12 h) by applying high voltage electrophoresis of rare earth elements. Because of the excellent separation, the rare earth elements can be determined by automatic β-liquid scintillation spectrometry with high counting yields.     

Bestimmung von Niob- und Zirkoniumspuren in Titandioxid und in Ilmenit

For the determination of traces of niobium and zirconium, TiO₂ and ilmenite are decomposed by fusion with boric acid and NaKCO₃. The mass is dissolved in 8 N HCl and Fe(III) extracted with di-iso-propylether. Thereafter Nb and Zr are separated from Ti by solvent extraction with tri-n-octyl phosphine oxide in cyclohexane. Both elements are backextracted with aqueous oxalic acid and determined by X-ray fluorescence or photometry with sulphochlorophenol S (Nb) or arsenazo III (Zr).     

Analyse von Gemischen aus Tri-, Di- und Monophenylzinnverbindungen und anorganischem Zinn(IV)

Triphenyl tin compounds are extracted as (C₆H₅)₃SnOSn(C₆H₅)₃ by CHCl₃ or CH₂Cl₂ from aqueous solution of pH 8.5. Diphenyl tin compounds are separated by solvent extraction with PAN/CHCl₃, diphenylcarbazone/CHCl₃, dithizone/CHCl₃, α-benzoinoxime/CHCl₃, PAR/i-Pentanol etc. Monophenyl tin compounds are extracted by Tropolone/CHCl₃, and inorganic tin(IV) is separated by diethyl dithiocarbaminate/CHCl₃ from acidified solution of pH 4. Several thin-layer chromatographic methods are given. The separated compounds are determined by radiometric or new photometric methods.     

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.     

The determination of trace amounts of zirconium,hafnium, thorium and cerium in silicate rocks

A method is described for the determination of traces of zirconium, hafnium, cerium and thorium in rocks. After the sample has been opened up, these elements are separated from the major component elements by extraction from 10 N nitric acid with a 40% solution of tri-n-butyl phosphate, cerium being oxidised with bro-mate. After back-extraction the elements are separated from each other and from other extracted elements by cation exchange. Zirconium is determined photometrically with quinalizarin sulphonic acid which gives about twice the sensitivity of alizarin red S. Thorium is determined photometrically with thorin, and cerium by utilizing its bleaching action on iron(II) phenanthroline. Hf is determined spectro-graphically.     

Cation-exchange separations in organic solvent-dithizone media

Numerous elements can be adsorbed on a column of the strongly acidic cation-exchange resin Dowex 50 from a mixture consisting of tetrahydrofuran and 1 M nitric acid (19:1). These elements include Ag, Cu, Bi, Pb, rare earths, alkaline earth metals, alkali metals, U, Th, Fe, Co, Zn and Cd; Hg and Sb are not retained and so can be separated from the adsorbed elements. Fractionation of the adsorbed elements can be effected by using as eluent 0.01 M dithizone in tetrahydrofuran-1 M nitric acid(19:1);; the dithizonates of silver, copper and bismuth are selectively eluted while the other adsorbed metal ions are still retained. The technique is suitable for the separation of tracer and macro amounts of elements.     

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.     

Spektrophotometrische Bestimmung von Nickel, Kobalt, Kupfer, Eisen und Zink in Niob

Zusammenfassung Nickel-, Kobalt-, Kupfer-, Eisen- und Zinkspuren werden als Diäthyldithiocarbamidatkomplexe durch Extraktion von Mob abgetrennt. Anschließend trennt man diese Elemente durch Anionenaustausch-Chromatographie voneinander und bestimmt sie in den einzelnen Fraktionen spektrophotometrisch. Die Nachweisgrenzen liegen für 0,5 g Einwaage bei 0,3 ppm Nickel, 0,1 ppm Kobalt, 0,3 ppm Kupfer, 0,3 ppm Eisen und 0,3 ppm Zink. Die Variationskoeffizienten der Bestimmungen schwanken in Abhängigkeit vom Spurengehalt bei den verschiedenen Elementen zwischen 4 und 24%.

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Summary Traces of nickel, cobalt, copper, iron and zinc are separated from niobium as diethyldithiocarbamidate complexes by extraction. Thereafter these elements are separated from each other by ion-exchange chromatography and determined spectrophotometrically. Amounts of 0.3 ppm of nickel, copper, iron and zinc and of 0.1 ppm of cobalt can be determined in 0.5 g of niobium. The relative standard deviations vary from 4 to 24% for the different elements in dependence of the contents of impurities.

     

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 of inorganic ions : The paper chromatography of germanium

Germaniuni(IV) may be separated from As and many other elements by paper chromatography with butanol saturated with 1 N HCl. The R_F value of germanium (IV) is 0.25 – 0.29.     

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.     

Quantitative extraktive abtrennung von zirkon und titan mit hilfe von n-heptylarsonsäure

Zirconium and titanium can be easily and quickly extracted from ca. 0.5 M hydrochloric, nitric or sulphuric acid by means of n-heptylarsonic acid in chloroform. The metal can be determined gravimetrically, or after some pretreatment, titrimetrically or photometrically. The extraction allows a quantitative separation from a large number of elements. The results obtained for technical products such as alloys and glass are compared with results of standard methods.     

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.     

Anion-exchange isolation of rare-earth elements from apatite minerals in methanol-nitric acid medium

Batch distribution coefficients, K_d, of rare-earth elements (REE) and other elements were determined radiochemically for a strongly basic nitrate anionexchange resin Dowex 1-X8 100–200 mesh, in nitric acid-methanol media of varying composition. This method was developed for the separate recovery of REE from apatite minerals. Calcium and other common elements of the apatite are eluted by a 5% (v/v) 7 M nitric acid-95% methanol mixture, while the REE are retained. The REE are recovered and separated into two fractions; the heavier REE by elution with a 45% nitric acid-55% methanol mixture, and a very clean fraction of La, Ce, Pr, Nd by elution with water.     

Untersuchungen über die Abtrennung und Bestimmung von Vanadium-Spuren

A method is reported for the determination by activation analysis of 28 elements occurring in organic and biological material in small concentrations and exhibiting as (n, γ)-products of half-life times > 10 hours. After irradiation and wet combustion, chemical separation of the elements may be achieved by solvent extraction and precipitation; chemical yields were ascertained on standardized mixtures. The influence of varying neutron flux was taken into account by cobalt standards. Activity measurement was done by gamma-ray scintillation spectrometry.     

Diorganostyrylzinndiorganophosphine und ihre tricarbonylnickel-komplexe

Diorganostyryltin chlorides R₂StySnCl (R = C₄H₉, p-CH₃C₆H₄, R₂ = (CH₂)₅) react with trimethylsilyl di-t-butylphosphine or trimethylsilyl diphenylphosphine to form trimethylchlorosilane and the corresponding diorganostyryltin-diorganophosphines, which can be separated and characterized by IR, NMR, Mössbauer and mass spectroscopy. With Ni(CO)₄ the tin—phosphorus derivatives give diorganostyryltin diorganophosphinetricarbonylnickel complexes.     

Extraktion von blei und wismut mit n-benzoyl-α-amino-capronsäure

Bismuth and lead may be separated from each other and from many other metals by successive extractions with N-benzoyl-α-aminocaproic acid in chloroform at pH 2.5–3.0 and 5.4–7.0, respectively.     

Solvent extraction separations with bpha. applications to the microanalysis of niobium and zirconium in uranium

A detailed study of the benzoylphenylhydroxylamine (BPHA)-chloroform-hydrochloric acid solvent extraction system with 52 elements is described with emphasis placed on extraction of the easily hydrolyzed transition metals from strong hydrochloric acid. From this study, a separation procedure for hafnium, niobium, tantalum, titanium, vanadium, and zirconium from uranium was developed, and procedures are given for the microanalysis of niobium and zirconium in uranium. Niobium and zirconium are separated from uranium by extraction into BPHA-chloroform from 10-N HCl.The separated elements are then measured colorimetrically as the niobium-4-(2-pyridylazo)resorcinol and zirconium-arsenazo III complexes. The limit of detection is 1 μg/g U.     

Zur Chemie und Strukturchemie der Phosphide und Polyphosphide. 20. Darstellung,Struktur und Eigenschaften der Alkalimetallmonophosphide NaP und KP

Chemistry and Structural Chemistry of Phosphides and Polyphosphides. 20. Preparation, Structure, and Properties of the Alkali Metal Monophosphides NaP and KP The monophosphides NaP and KP were prepared by reaction of the elements in sealed glass ampoules at 725 K and 765 K, respectively. NaP yields as black reflecting needles, whereas KP is formed as microcrystalline substance with colour of coke. The compounds react very rapidly with aqueous reagents forming solid polymeric yellow phosphanes (PH)_x and partially gaseous products. NaP and KP crystallize in the novel orthorhombic NaP type (P 2₁2₁2₁; a = 603,8 pm; b = 564.3 pm; c = 1 014.2 pm and a = 650.0 pm; b = 601.6 pm; c = 1 128.8 pm; Z = 8, respectively) characterized by onedimensional infinite ¹∞(P^?) helices of covalent twofold bonded P-atoms with mean bond length P? P = 223.9 pm. The compounds can be described as Zintl-phases with M⁺ and P^? with respect to the structure. The range of existence of the NaP type and the LiAs type structure can be separated by the radii ratios. The volume increment for P^? is V(P^?) = 18.0 cm³mol^?1. For the bond energy E(P? P) in the monophosphides a value of 248 kJ · mol^?1 is calculated. The structures are discussed in detail together with related compounds.     

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.