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1.
A procedure for the determination of the three main isotopes of thorium in gas lantern mantles by alpha-spectrometry has been developed. The samples examined were dissolved in concentrated nitric acid and thorium was precipitated as hydroxide. Thorium was then dissolved in hydrochloric acid to be extracted into a TOPO solution, back-extracted with sulfuric acid, electrodeposited onto a steel disc and finally counted alpha-spectrometrically. The radiochemical recovery for thorium was 94% with a counting efficiency of 37%.  相似文献   

2.
A method is described for the spcctrophotometric determination of microgram quantities of silicon in the presence of thorium. Thorium oxide is dissolved by heating it at 70 to 8o°C in 4M HNO3 that contains 2 drops of HF. Under these conditions, no silicon is lost through volatilization. The silicon is estimated as the blue ailicomolybdate complex. Under the conditions selected for development of color, a precipitate of thorium molybdate is obtained ; the thorium molybdate is, however, dissolved without affecting the color of the complex by the addition of tartrate and adjusting the pH of the solution to 3.0. The lower limit of detection is about 5 p.p.m. of silicon.  相似文献   

3.
Das M  Heyn AH  Hoffman MZ 《Talanta》1967,14(3):439-441
Thorium was precipitated from homogeneous solution by photochemical reduction of periodate to iodate in a solution containing thorium and perchloric acid, by means of a 2537 A low-pressure mercury vapour lamp. For weighing, the precipitate was redissolved, precipitated once as thorium hydroxide, and finally as thorium oxalate, which was ignited to thorium dioxide. Quantitative results were obtained in the range 35-180 mg of thorium.  相似文献   

4.
It has been shown that thorium could be precipitated quantitatively in 40% nitric acid solution as iodate, in presence of oxalic acid which complexes all those elements that interfere seriously in the usual iodate procedure. Thorium is thus freed from all the cations in a single operation from solutions containing sulphate and phosphate radicals. The method is very quick and thorium oxide in a sample of monazitc could be estimated with precision in 8–9 hours.  相似文献   

5.
A simple method is described for the solvent extraction of thorium. Thorium is extracted quantitatively from 5·10–3M sodium salicylate solution at pH 2.5–3.25 using 2.16·10–2M triphenylphosphine oxide as an extractant dissolved in toluene. The extracted metal ion is stripped with hydrochloric acid (0.1M) and determined spectrophotometrically with Thoron-1 at 540 nm. The method permits separation of thorium from lanthanum, cerium, neodymium, samarium and uranium from binary mixtures and is applicable to the analysis of monazite sand. The method is precise, accurate and selective.  相似文献   

6.
微色谱柱分离-光度法测定高稀土铁矿石中的微量钍   总被引:3,自引:0,他引:3  
采用HD-8微色谱柱对高稀土铁矿石样品(白云鄂博矿)中的钍进行分离富集,探讨了影响其分离富集的条件。实验表明,在4 mol/L HCl介质中钍可被树脂完全吸附,用3 mL 40 g/L草酸铵溶液可以从吸附柱上完全解吸钍,并结合偶氮胂Ⅲ分光光度法进行测定。所建立的方法适合于含铁、稀土量高的矿石样品中微量钍的分离与测定。  相似文献   

7.
A very rapid method for the estimation, of trace amounts of thorium up to 0.01 per cent. or thereabouts even in complex minerals like ilmenite and columbitetantalite has been described. Thorium is collected in an acid solution with phosphates of zirconium and titanium without prior separation of silica, after decomposition of the mineral with sodium peroxide. Thorium is next collected as fluoride with lanthanum as a carrier, precipitated as thorium iodate in potassium iodate-oxalic acid mixture and finally titrated against 0.01N sodium thiosulphate. Accurate results are obtained within a short time of two working days.  相似文献   

8.
Thorium forms a pinkish-violet coloured complex with dinitrosochromotropic acid, which has been used as an indicator in the titrimetric determination of thorium with EDTA. The method is based on the fact that this coloured complex is less stable than the thorium-EDTA complex and breaks down after a bulk of thorium has reacted with EDTA; this marks the end-point, which is the change from pinkish-violet to red. am little as 3.1 mg of thorium present in 50 ml volume of solution may be accurately determined within a pH range from 2.2 to 3.5. The study of interferences revealed that quite a number of elements do not interfere; iron may be masked with ascorbic acid. Thorium may be determined by the same method, after separating it from many interfering ions by precipitating it with o-anisilic acid.  相似文献   

9.
Preetha CR  Gladis JM  Rao TP 《Talanta》2002,58(4):701-709
The preparation of solid reagent 5,7-dichloroquinoline-8-ol modified benzophenone for preconcentration of thorium is described. The thorium-5,7-dichloroquinoline-8-ol complex is quantitatively retained on benzophenone in the pH range 6.0-6.5. The solid mixture consisting of the metal complex together with benzophenone is dissolved in 5 ml of acetone and thorium content was established spectrophotometrically by using Arsenazo III procedure. Calibration graphs are rectilinear over the thorium concentration range 0.001-0.2 mug ml(-1). Five replicate determinations of 20 mug of thorium present in 1 l of sample solution gave a mean absorbance of 0.320 with a relative standard deviation of 2.9%. The detection limit corresponding to three times the standard deviation of the blank was found to be 0.0005 mug ml(-1). The developed procedure has been successfully utilized for the estimation of thorium content of pure Rare earth chloride solution collected from Indian Rare Earths (IRE) Limited, Alwaye.  相似文献   

10.
Thorium has been determined volumetrically. It has been precipitated with m-nitrobenzoic acid according to the method of Neish. Thorium m-nitrobenzoate has been then dissolved in sulphuric acid and titrated with titanous chloride to determine the NO2-group which gives the amount of thorium directly.  相似文献   

11.
A method for the isolation from siliceous materials of carrier-free chemically and radiochemically pure thorium is described. The method was applied and tested on several shale and deep-sea sediment samples used in the application of the Thorium Isotopes Method to the Dating of Marine Sediments. The chemical procedure consistently produces pure thorium in good yields. Several samples can be prepared simultaneously in a few hours.  相似文献   

12.
Das M  Heyn AH  Hoffman MZ  Agarwal RP 《Talanta》1970,17(10):925-935
Thorium was precipitated from homogeneous solution by exposing solutions of thorium and periodate in dilute perchloric acid to 253.7 nm radiation from a low-pressure mercury lamp. Periodate is reduced photochemically to iodate which causes the formation of a dense precipitate of the basic iodate of thorium(IV). The precipitate was redissolved, the iodate reduced, the thorium precipitated first as the hydroxide, then as the oxalate and ignited to the dioxide for weighing. Thorium(IV) solutions containing 8-200 mg of ThO(2) gave quantitative results with a standard deviation (s) of 0.2 mg. Separations from 25 mg each of iron, calcium, magnesium, 50 mg of yttrium and up to 500 mg of uranium(VI) were quantitative (s = 0.25 mg). Separations from rare earths, except cerium, were accomplished by using hexamethylenetetramine rather than ammonia for the precipitation of the hydroxide. Cerium(III) was similarly precipitated and converted into CeO(2) for weighing. Quantitative results were obtained for 13-150 mg of CeO(2) with a standard deviation of 0.2 mg. Separations from 200 mg of uranium were quantitative. Other rare earths and yttrium interfered seriously. The precipitates of the basic cerium(IV) and thorium iodates obtained are more compact than those obtained by direct precipitation and can be handled easily. Attempts to duplicate Suzuki's method for separating cerium from neodymium and yttrium were not successful.  相似文献   

13.
p-Aminosalicylic acid (PAS) can be successfully utilized as a reagent for gravimetric and volumetric determination of thorium. A quantitative precipitate of thorium is obtained by adding a hot 2% solution of PAS, in the presence of a little ammonium acetate at a pH range between 4 and 5.6. The thorium salt filters, washes and ignites readily. Thorium content of the salt can be determined directly by ignition to thoria, and indirectly by the quantitative bromination of the organic ligand with bromide-bromate mixture or by iodination with iodine monochloride in glacial acetic acid solution at 0° C. The processes give comparable results.  相似文献   

14.
Summary In the present work the adsorption behaviour of uranium and thorium was investigated on the strongly basic anion exchange resin Dowex 1 in ketone media containing hydrochloric or nitric acid. As a result of these studies two methods for the separation of uranium from thorium in acetone solution were developed.
Zusammenfassung In der vorliegenden Arbeit wurde das Adsorptionsverhalten von Uran und Thorium am stark basischen Anionenaustauscher Dowex 1 in salzs?ure- und salpeters?urehaltigen Ketonen untersucht. Es wurden zwei Methoden zur Trennung des Urans von Thorium in acetonhaltiger L?sung entwickelt.
  相似文献   

15.
Thorium-zirconium binary alloys are analysed by complexometric procedures. For alloys containing more than 20% thorium or 5% zirconium by weight, the sum of the constituents is obtained by a back titration procedure at pH 2.6–2.8 with bismuth nitrate using xylenol orange as indicator. Thorium is then masked with sulphate and the liberated EDTA is titrated with bismuth at pH 1.2–1.3. For alloys containing less than 20% of thorium, thorium fluoride is precipitated on lanthanum fluoride to effect its separation before titration. For alloys containing less than 5% of zirconium, the zirconium is separated by precipitation with p-bromo-mandelic acid.  相似文献   

16.
Toribara TY  Koval L 《Talanta》1967,14(3):403-407
A scheme for the isolation of subpicogram to microgram amounts of thorium from bone and soft tissue samples is described. Thorium is first collected by co-precipitation with iron(III) hydroxide and then adsorbed by a cation-exchange resin column from a concentrated hydrochloric acid solution of the precipitate. A double precipitation is necessary for bone samples whereas a single precipitation suffices for liver samples. The thorium is eluted from the column with an ammonium carbonate solution which is then evaporated to dryness to effect the isolation. Good recoveries of thorium from bone samples are obtained.  相似文献   

17.
Thorium was extracted from a mixture of nitric acid and NaNO3 of 0.01M each at pH 2.2 on a column of silica gel coated with TOPO. Thorium was separated from alkalis, alkaline earths, chromium, iron, cobalt, nickel, zinc, cadmium, mercury, lead, trivalent rare earths, platinum group metals, chloride, phosphate and acetate in binary mixtures by selective extraction of thorium. Thorium was separated from cerium (IV), zirconium, uranium and molybdenum by selective elution of thorium with 0.01M H2SO4. The method was extended for the analysis of thorium in monozite ore.  相似文献   

18.
A dioxan-antipyrine solvent mixture is used to separate thorium and uranium — on sheet chromatograms — from the monazite sand solution. Thorium is estimated by an indirect EDTA titration method, using pyrocatechol violet, Uranium is estimated spectrophotometrically by the hydrogen peroxide method.  相似文献   

19.
A method for the sequential determination of thorium and plutonium has been developed. In the sample solution containing thorium and plutonium, thorium is first determined by complexometric titration with EDTA and then in the same solution plutonium is determined by redox titration employing potentiometry. Prior to the determination of plutonium, EDTA is destroyed by fuming with concentrated HClO4. Thorium is determined at 10 mg level and plutonium at 1 mg level with precision and accuracy of better than ±0.5%.  相似文献   

20.
《Analytical letters》2012,45(19-20):2001-2009
Abstract

Thorium(IV)salts were found to act as catalysts for the alkylation of 4-(p-nitrobenzyl)pyridine by T-2 toxin. Using thorium(IV)chloride as the catalyst, a detection procedure for T-2 toxin was developed that required a heating step consisting of only 2 minutes at 90°C. The limit of detection of T-2 toxin with this procedure was found to be 1 microgram.  相似文献   

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