A gas-jet system for the study of short-lived,light fission products

A selective method for the solvent extraction and spectrophotometric determination of uranium(VI) is described. Uranium can be extracted into chloroform at pH 6.0 with N-m-chlorophenyl-2-theno-hydroxamic acid (N-m-CPTHA) and determined by spectrophotometry using 1-(2-pyridylazo)-2-naphthol (PAN). The molar absorptivity is 1.50·10⁴ 1·mol^–1·cm^–1 at 560 nm. The system obeys Beer's law within the range 0.95–20.00 ppm of uranium. Alternatively, a back-extraction procedure was also developed in which uranium is back-extracted by nitric acid and estimated spectrophotometrically using Arsenazo III. The molar absorptivity is 2.0·10⁴ 1·mol^–1·cm^–1 at 665 nm. The parameters concerning the optimum conditions for the analytical method are discussed. The proposed method is applied precisely for the determination of uranium in rock and sea water samples.     

Analysis of trace uranium in Indian tobacco samples

The trace uranium concentrations have been determined in tobacco obtained from different brands of commercially available cigarette, beedi, chewing tobacco and also in pan masala, using fission track registration technique. Consumption of tobacco orally or by smoking may result in the intake of radioactive elements into the human body causing hazardous effects. External detector method was employed for the determination of uranium using Makrofol-KG as the fission track detector. The range of uranium was found to vary between 0.066–0.106 ppm, 0.042–0.079 ppm and 0.043–0.092 ppm, in tobacco from samples of cigarette, beedi and chewing tobacco, respectively, and between 0.073–0.203 ppm in pan masala samples.     

Determination of uranium by fluorescence method

The paper describes a procedure for the determination of uranium in dilute solutions by fluorescence method. Factors influencing the determination in a phosphoric acid medium were studied. The detection limit of uranium determination is 0.04–0.05 ppm.     

Neutron activation determination of the uranium content of the primary coolant of water-water nuclear reactors

A neutron activation method for determination of uranium dissolved in the coolant of the first cycle of nuclear power stations is proposed. The method is based on preliminary concentration on activated carbon, irradiation with epithermal neutrons and gamma-spectrometry of²³⁹Np. The detection limit amounts to 1,3·10^–8 U/l. The method was sucessfully applied for the determination of uranium in the coolant of a nuclear power station.     

Extraction and spectrophotometric determination of uranium in phosphate fertilizers

An extraction and spectrophotometric method for determination of trace amounts of uranium in phosphate fertilizers is described. It is based on the extraction of uranium with trioctylphosphine oxide in benzene and the spectrophotometric determination of uranium with Arsenazo III in buffer-alcoholic medium. The maximum absorbance occurs at 655 nm with a molar absorptivity of 1.2·10⁴ l·mol^–1·cm^–1. Beer's law is obeyed over the range 0.6–15.0 g·ml^–1 of uranium(VI). The proposed method has been applied successfully to the analysis of phosphate fertilizers with phosphate concentrations of 45% P₂O₅.     

Spectrophotometric determination of uranium in sea water with thiocyanate and rhodamine B

Summary Spectrophotometric Determination of Uranium in Sea-Water with Thiocyanate and Rhodamine B In the presence of a large excess of thiocyanate uranium(VI) forms a violet colour with Rhodamine B. The complex can be stabilized by addition of poly (vinyl alcohol). The calibration graph for measurement at 600 nm is linear in the range 0.5–10g of uranium per 25ml, the molar absorptivity being 3.56×10⁵1-mole^–1·cm^–1. The effect of foreign ions has been studied and the method can be applied to the determination of uranium in sea-water, with reliable results. Uranium is preconcentrated from sea-water by a flotation procedure with toluene in presence of benzoate and Safranine T, with nitrilotriacetic acid as masking agent. The method is highly selective for uranium, with a recovery of 97.9–99.2%.     

Separation and determination of uranium(VI) with calixarene hydroxamic acids

A new calixarene hydroxamic acid, 5,11,17,23-tetra-(N-p-chlorophenyl hydroxamate c-phenyl-25,26,27,28-tetrahydroxycalix[4]arene (CPCHA) was synthesized and used for the extraction and spectrophotometric determination of uranium(VI). The molar absorptivity of the uranium(VI)-CPCHA-thiocyanate complex was 9.9·10³ 1·mol^–1·cm^–1 at 436 nm. The system obeyed Beer's law in the range of 1.78–23.1 ppm of uranium. The uranium(VI)-hydroxamate-ethyl acetate complex was directly aspirated for graphite furnace atomic absorption spectrometry measurements (GFAAS) which increased the sensitivity by about a factor of fifty. Uranium was determined in various standard and environmental samples.     

A potentiometric method for the determination of uranium by stannous chloride reduction

A potentiometric method has been developed for the determination of uranium using stannous chloride as reductant. The oxidation of excess stannous chloride was accomplished with an excess of sodium nitrite, the excess of which was destroyed by sulfamic acid. The U(IV) was then determined by potentiometric titration with standard potassium dichromate. For 3–5 mg amounts of uranium the precision obtained was better than 0.3%.     

Determination of nitrate in thorium,uranium and plutonium solutions

A potentiometric titration method and a conductometric titration method were standardized for the determination of nitrate in thorium, uranium and plutonium solutions in the range of 2–10 mg, and 15–30 mg, respectively, with a precision and accuracy of 2% in both cases. The results were compared with those of other methods like Devarda's alloy reduction method and volumetric titration method. The procedures standardized have been recommended for the determination of nitrate in heavy element solutions used for the preparation of oxide and mixed oxide microspheres by the sol-gel technique.     

Liquid-liquid extraction and spectrophotometric determination of uranium with n-phenyl-3-styrylacrylohydroxamic acid (PSAHA)

A rapid, selective and sensitive liquid-liquid extraction and spectrophotometric method for the separation and microgram determination of uranium using PSAHA is described. Uranium is extracted with PSAHA into chloroform at pH 6.0–6.8. The U-PSAHA chelate is orange red in color having maximum absorbance at 410 nm and molar absorptivity 1.2·10⁴l·mol^–1·cm^–1. The system obeys Beer's Law in the range of 1.2 to 22.00 ppm of uranium. The uranium is determined in sea water and rock samples.     

Spectrophotometric determination of uranium with 5-(2′-carboxyphenyl)azo-8-quinolinol in the non-ionic micellar medium of Triton X-100

Triton X-100, a non-ionic surfactant, has been used to sensitize the reaction of 5-(2-carboxyphenyl)azo-8-quinolinol with uranium in aqueous medium at pH 5.2–6.1 to form a wine red coloured complex. The micellar sensitization results in two and a half-times enhanced molar absorptivity enabling the determination of uranium in rock samples at ppm level, stability of the complex enhanced from 4 hours to at least 72 hours. Extraction of the complex is avoided making the procedure simple, rapid and easy in operation. The molar absorptivity and Sandell's sensitivity of the complex are 1.50·10⁴l·mol^–1·cm^–1 and 15.9 ng·cm^–2, respectively, at _max=568 nm. Beer's law is obeyed over the range 0–3.3 g·ml^–1 of uranium. An amount as low as 0.19 g·ml^–1 of uranium could be determined satisfactorily within a relative standard deviation of ±1.3%. The limits of determination and practical quantitation are 0.29 and 1.80 ppm, respectively. The method was applied to the determination of uranium in soil, stream sediment and rock samples.     

4-(21-thiazolylazo) resacetophenone oxime. A new analytical reagent for the spectrophotometric determination of uranium (VI)

4-(2¹-Thiazolylazo) resacetophenone oxime forms a pink colored soluble complex with uranium(VI) in buffer solutions of pH 6.0. The colored complex has a maximum absorbance at the wavelength 572 nm and the color is stable for about 48 h. The system obeys Beer's law over the concentration range 0.2–6.0 g of uranium cm^–3. The molar absorptivity and the Sandell sensitivity of the complex are 6.2×10⁴ dm³.mol^–1.cm^–1 and 0.0038 g cm^–2, respectively. Effect of various diversions has been studied and the method was successfully applied for the determination of uranium in rock samples.     

A precise uranium assay using solvent extraction and spectrophotometry

The uranium spectrophotometric measurement using the uranylnitrate-quaternaryamine solvent extraction method is investigated to identify factors that affect precision and accuracy of the uranium determination. The inherent spectrophotometric precision was measured with neutral density filters in the sample light path and was found to be <0.1% relative standard deviation (RSD). Under selected experimental conditions, temperature instability has a –0.02% effect on the extraction, and a –0.4% effect on the absorbance of the uranium extract in 2-nitropropane (2-NP) or methyl isobutyl ketone (MIBK) solvents. Under optimum conditions at the 10 mg uranium level, RSDs of 0.1% resulted.     

X-ray fluorescence method for the determination of rare earths, uranium and thorium in allanites

Summary An X-ray fluorescence (XRF) method for the determination of La, Ce, Pr, Nd, Sm, Gd, Th and U in allanites is described. The estimation limits for different impurity elements are La 0.5–10%, Ce 2–20%, Pr 0.1–2.0%, Nd 0.5–10%, Sm 0.1–2%, Gd 0.1–2.0%, Th 0.2–4% and U 0.2–4%. The sample is diluted in the ratio of 19 by boric acid and double layer pellets are prepared. The precision of the method which varies from 0.2–15% has been determined for every element in each standard. Accuracy of the method is assessed by comparison of the values for rare earth, thorium and uranium content with those obtained by optical emission spectroscopic method and the values for uranium and thorium with those obtained by neutron activation analysis.

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Röntgenfluorescenzmethode zur Bestimmung von Seltenen Erden, Uran und Thorium in Allaniten

Zusammenfassung Das beschriebene Verfahren eignet sich zur Bestimmung von La, Ce, Pr, Nd, Sm Gd, Th und U in Allaniten. Die Bestimmungsgrenzen für die einzelnen Elemente betragen: La 0,5–10%; Ce 2–20%; Pr 0,1–2%; Nd 0,5–10%; Sm 0,1–2%; Gd 0,1–2%; Th 0,2–4%; U 0,2–4%. Die Probe wird mit Borsäure im Verhältnis 19 vermischt und zu Doppelschicht-Tabletten gepreßt. Die Reproduzierbarkeit beträgt 0,2–15% und wurde für jedes Element im jeweiligen Standard bestimmt. Die Richtigkeit des Verfahrens wurde durch Vergleich mit Ergebnissen der Emissionsspektralanalyse (SE, U) sowie der Neutronenaktivierungsanalyse (U, Th) beurteilt.

     

Direct Determination of Uranium in the D2EHPA-TOPO Organic Phase Using EDXRF Spectrometry

The determination of uranium in liquid samples using energy dispersive X-ray fluorescence was investigated. The organic phase di-(2-ethyl hexyl) phosphoric acid and trioctyl phosphine oxide (D2EHPA-TOPO)/kerosene, which resulted from first and second cycles of uranium extraction from commercial phosphoric acid, was directly analyzed using ¹⁰⁹Cd as a primary excitation source. Copper was used as an internal standard, which led to a linear relation between relative intensity of uranium and its concentration. Three calibration curves, 0–100, 100–1000 and 1000–6500 g· ml^–1, according to uranium concentration in the studied samples, were constructed. The effect of different molarities of D2EHPA and TOPO was considered. The detection limit, precision and accuracy were 1.1 g · ml^–1, 3% and 1.4%, respectively. The obtained results were compared with other techniques such as -ray spectroscopy, UV spectrometry and volumetry.     

A sensitive spectrophotometric method for the determination of trace amounts of uranium(VI) using 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone

The reaction between uranium(VI) and 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone (2HNAINH) has been investigated in HCl-sodium acetate buffers and a highly sensitive and simple procedure for the determination of uranium(VI) is suggested. The orange red colored complex showed maximum absorption at 430 nm in buffer solutions of pH 3. Beer's law is obeyed in the range of 0.2 to 33 g ml^–1. The molar absorptivity and Sandell's sensitivity are found to be 9.6×10³ mol·l^–1 and 0.025 g cm^–2, respectively. The composition of the complex between metal and reagent is found to be 11. The effect of diverse ions is also studied and the method is successfully applied for the determination of uranium in synthetic mixtures.     

Synergistic extraction and separation studies of uranium(VI)

A method is described for the extractive separation and spectrophotometric determination of uranium(VI) from an aqueous solution of pH 5.0–7.0 using benzoylacetone (bzac) and pyridine (py) dissolved in toluene as extractants. The extracted species are UO₂(bzac(₂·2py. The method provides separation of uranium(VI) from lanthanum(III), samarium(III), neodymium(III), cerium(III) and thorium(IV). The method is precise, accurate, fast and selective.     

Potassium ferrocyanide as a spectrophotometric reagent for the determination of uranium

Potassium ferrocyanide gives a colour reaction with U(VI), which is suitable for its determination. The complex absorbs in the wavelength range of 390–397 nm. The optimum pH range for colour development was 1.5–3.5. The molar absorptivity was found to be 4.65·10³ 1·mol^–1·cm^–1. Most of the anions up to 1000 g did not interfere. The method was made selective by extracting U(VI) first with DOSO from the mixture of interfering cations from 1–2M HNO₃ medium and then determining uranium in the back-extracted solution by developing the colour with ferrocyanide. 20 g/10 ml of U(VI) in the final solution could be satisfactorily determined within an RSD of ±2%.     

Extraction of uranium with 2,3-dihydroxynaphthalene and cetyltrimethylammonium bromide, and its fluorimetric determination in silicate rocks

A novel procedure for the extraction of uranium has been described. UO₂ ²⁺ forms a 1:3 anionic complex with 2,3-dihydroxynaphthalene in the pH range, 4–12. This anionic complex is best extracted into ethyl acetate at pH 11–12 under the influence of a counter cation, cetyltrimethylammonium bromide. This extraction technique has been extended to the separation of uranium from silicate rock matrices for its determination by fluorimetry. Except Co, Cr, and Fe, most elements present in silicate rocks do not interfere. While the interferences of Co and Cr are suppressed by the addition of EDTA, iron is removed by prior extraction at pH 4–5 as its neutral complex with 2,3-dihydroxynaphthalene. The results compare favourably with those obtained from the conventional technique, i.e., extraction of uranium in ethyl acetate from NHO₃ medium under the influence of Al(NO₃)₃ ^.9H₂O as salting out agent. The extraction system under study is capable of separating even ultra-trace amounts of uranium quantitatively from complex matrices of rock samples. Besides, the method is simple, rapid, cost effective and precludes the use of reagents like nitric acid and aluminum nitrate (salting out agent) required in bulk quantities in the conventional system.     

Simultaneous determination of uranium(IV) and iron(II) with a stopped-flow inductive kinetic spectrophotometric method

A kinetic method for simultaneous determination of multielements is proposed, and a procedure for simultaneous determination of uranium(VI) and iron(II) is established based on their inductive effect on the chromium(VI)-iodide redox reaction in weak acidic medium. The reaction was monitored with the stopped-flow spectrophotometric technique by using I ₃ ^– -starch complex as indicator. The calibration graphs are linear for 0–3.6 g.cm^–3 U(IV), and 0–2.5 g.cm^–3 Fe(II), respectively. Most foreign ions, except for V(IV), Sb(III), do not interfere with the determination.