Radiochemical neutron activation determination of phosphorus in high pure germanium

A radiochemical procedure for determination of ultra low concentrations of phosphorus in germanium has been developed. The method involves application of multicells autoclaves for matrix distillation and extraction chromatography with dioctyltin diacetate for final phosphorus purification. The detection limit is 40 ppt for a 1-g sample.     

Radiochemical determination of As,Cr, Mo,Sb and Se in foods

A radiochemical neutron activation analysis procedure was applied to the analysis of foods for As, Cr, Mo, Sb and Se. The elements are retained on an inorganic chromatographic resin of hydrated managanese dioxide while interfering elements are removed. Activities from Br, K, Na and P interferences are reduced by up to six orders of magnitude, and detection limits for food analysis are reduced by factors of 100–2000, compared with those normally found for instrumental neutron activation analysis. Detection limits for the foods analyzed are 0.1–0.3 ng/g for As and Sb and 1–10 ng/g for Cr, Mo and Se. Results are presented for various foods and several National Bureau of Standards Standard Reference Materials.     

Radiochemical multielement neutron activation analysis of tungsten

A radiochemical neutron activation technique for the detemination of 19 elements in high purity tungsten has been developed. It is based on extraction with diantipyrylmethane (for tantalum and antimony), substoichiometric extraction of molybdophosphate (for phosphorus) and anion-exchange chromatography (other elements) in hydrofluoric acid medium. The results obtained and achievable limits of detection are given. The effects of self-shielding and nuclear interfering reactions are discussed.     

Radiochemical determination of antimony

A radioanalytical method based on substoichiometric principles has been developed for the extraction and determination of antimony/III/ with 1-/2-pyridylazo/-2-naphthol /PAN/. Antimony/III/ forms a red complex with PAN in the presence of I^– or Br^–, which is extractable into benzene from sulphuric acid media.     

Radiochemical determination of technetium-99

The radiochemistry of technetium-99 is reviewed and the different measurement techniques are compared. Experimental results on sorption of technetium on two different types of ion exchange resins using^99mTc and^95mTc as chemical yield tracers are presented. Spectra calibrations of liquid scintillation counter using^95mTc as chemical yield tracer of⁹⁹Tc are discussed.     

Radiochemical determination of ruthenium-106 in urine

The method is based on volatilization of Ru in the form of RuO₄ by distillation of wetashed urine with KMnO₄, precipitation of Ru hydroxide, and β-counting. Before the distillation, most of the organic compounds are destroyed by wet-ashing with H₂SO₄ and 30% H₂O₂ at 140°C, with subsequent evaporation until fuming. The chemical recovery is determined photometrically at 430 nm using the solution of β-counted Ru hydroxide in KIO₄/KOH reagent. The mean recovery is about 70%.     

Radiochemical determination of low unsaturations in polyisobutene

A radiochemical technique involving the use of ³⁶Cl has been described previously for the measurement of butyl rubber unsaturations. This method has now been applied to the estimation of the much lower concentration of double bonds present in polyisobutene prepared by the cationic polymerization of isobutene at a low temperature. The nature of the reaction of polyisobutene with radiochlorine in the absence of air is examined, and the experimental results are discussed in relation to present theories of the mechanisms of chain termination in cationic polymerization.     

Radiochemical determination of oxygen traces in selenium

A sensitive method for determination of oxygen in selenium is described. Oxygen is converted into the gaseous compound sulfur dioxide labelled with³⁵S. The β-radiation of³⁵S is measured by liquid scintillation counting. The detection limit is 0.02 ppm. The efficiency of vacuum distillation in the purification of selenium, and the influence of air, dry oxygen and water on the absorption of oxygen by selenium have been investigated.     

Radiochemical determination of caesium-137 in liquid milk

Summary A simple and rapid method is described for the radiochemical determination of a caesium-137 in liquid milk. After the addition of caesium carrier the milk sample is deproteinized with nitric acid, filtered and alkaline earths removed by oxalate precipitation. From the decanted solution caesium is precipitated with sodium cobaltinitrite, separated from potassium as caesium silicotungstate and finally counted as dipicrylaminate by an anticoincidence beta counter. The radiochemical yields for caesium amount to about 65%. Good agreement is found between results obtained by the present method and by the gamma spectrometry. The results for caesium-137 content may be obtained within 6 hours.

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Zusammenfassung Es wird eine einfache und schnelle Methode zur radiochemischen Bestimmung von Caesium-137 in flüssiger Milch beschrieben. Die zu untersuchende Milch wird nach Zusatz des Caesiumträgers mit Salpetersäure enteiweißt. Aus der dekantierten Lösung werden die Erdalkalien als Oxalate abgeschieden. Das Radiocaesium wird mit Natriumnitritocobaltat gefällt, von Kalium mit Silicowolframsäure getrennt und endlich als Caesiumdipikrylaminat in einem Beta-Antikoinzidenzzähler gemessen. Die Caesiumträgerrückgewinnung beträgt durchschnittlich 65%. Die nach der beschriebenen Methode erhaltenen Resultate stehen in guter Übereinstimmung mit denen der gammaspektrometrischen Bestimmung. Der Radiocaesiumgehalt in Milch kann innerhalb von 6 Std bestimmt werden.

     

Radiochemical determination of cadmium isotopes in radioactive debris

(109)Cd and (113m)Cd were produced in a high altitude nuclear explosion during 1962. Analysis of filters from aircraft and balloon samplers enables the products of this single detonation to be traced. A radiochemical procedure is presented which allows determination of the cadmium radionuclides in the course of a sequential analysis for fission products and activation products from nuclear weapons tests. The sensitivity, recovery and decontamination from other radionuclides are adequate.     

Radiochemical determination of cobalt-60 in environmental samples

A procedure for the radiochemical determination of (60)Co in low-activity samples of sediment and biological material is described. Cobalt recovery is high and decontamination from tervalent lanthanides and naturally-occurring radionuclides is complete. Cobalt is precipitated with 1-nitroso-2-naphthol, decontaminated from iron by precipitation of the iron as ferric phosphate, extracted into methyl isobutyl ketone, and finally precipitated as cobalt mercury(II) thiocyanate for yield determination and beta-counting.     

Radiochemical determination of fission products of uranium

An analysis has been elaborated to determine the long-living γ-emitting fission products of uranium. It consists of a sodium bisulphate melt of the fission product solution or the U-fuel, followed by liquid-liquid extractions. Afterwards the isotopes are absolutely counted with a standardized 3″×3″ NaI crystal. The total γ-spectrum of the original fission product solution, taken with a NaI crystal or a Ge−Li detector, is also analyzed mathematically by mixed γ-spectrometry. From a short post-irradiation of the fission product solution the concentrations of both²³⁵U and²³⁸U are determined. The absolute amount of fission products related to the U-concentration allows the calculation of the percent atomic burn-up, the irradiation time, the cooling period, the flux of the reactor and the original degree of enrichment of the uranium. Research associate of the I. I. K. W.     

Extraction-spectrophotometric determination of tungsten as tungsten blue

Tri-n-butyl phosphate (TBP) is used to extract tungsten(IV) from 0.5 M hydrochloric acid containing molybdenum(VI) and other metals. Tungsten(VI) in the TBP solution is reduced by tin(II) chloride and n-butyl acetate is used for dilution. The tungsten blue formed in the TBP/n-butyl acetate medium (1:1) is measured at 615 nm. The apparent molar absorptivity is about 1000 1 mol^?1 cm^?1; calibration graphs are linear in the range 0.1–1.5 mg of tungsten.     

Radiochemical determination of trace noble metals in silver artefacts

Radiochemical separations are essential for the determination of trace elements in silver artefacts by neutron activation analysis due to the high levels of both short and long-lived activities produced by the matrix, but the sensitivity of the technique permits the examination of small samples. The noble metals are considered most significant from a diagnostic standpoint, and radiochemical techniques have been developed for their determination in samples of a few milligrams. Methods have been investigated for the determination of Pd, Rh, Ir and Pt in samples removed from museum specimens of known provenance.     

Radiochemical determination of chromium in biological tissues by ion-exchange

A simple ion exchange procedure has been developed for the separation of chromium from the other chemical elements in biological tissues. This procedure combined with neutron activation analysis has been applied successfully to the determination of chromium in a reference biological material. The precision was ±11%, the accuracy 3% and the sensitivity found was 10 ng with only 20 hrs irradiation at 2.8·10¹³ n·cm⁻²·sec⁻¹ flux The main steps of the procedure are: wetdigestion of the irradiated tissue, oxidation to chromium (VI), fixation onto an anion resin in sulfate form, washing of the resin with 1N H₂SO₄, collection of chromium by reductive elution for counting and finally determination of the chemical yield by reactivation.     

Spectrographic determination of impurities in ultrapure tungsten and tungsten oxide

The effects of an external magnetic field and of the diameter of the anode on the spectroscopic line intensity of the impurity elements in ultrapure tungsten and tungsten oxide have been studied. The results obtained are used for the development of a more sensitive method for the determination of these impurities (Mn, Pb, Fe, Ni, Al, Mo, V, Cu, Cr).     

Radiochemical separation of rhenium(VII) from tungsten(VI)

The absorption of rhenium(VII) and tungsten(VI) ions on Al₂O₃ from HCl, HClO₄, HNO₃, H₂SO₄, H₃PO₄, NaOH, NH₄OH, NaCl, NaF, and Na-tartarate solutions by batch equilibration, as well as by passage through a chromatographic column, has been studied. The results show that rhenium(VII) can be effectively separated from tungsten(VI) using any of the acid or salt solutions investigated. The experimental data allowed to develop a simple procedure for the radiochemical separation of rhenium isotopes from an irradiated WO₃ sample.     

Radiochemical solvent extraction of molybdenum/VI/ using99Mo tracer

A radiochemical solvent extraction method has been developed for the micro determination of Mo/VI/ using⁹⁹Mo tracer. It involves removal of^99mTc by ethyl methyl ketone /EMK/ and extraction of Mo with tri-n-butyl phosphate /TBP/ from 5M HCl. Different parameters affecting the extraction such as pH dependence, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 2 g of Mo.