Method for the determination of thorium and uranium in urine by ICP-MS

ICP-MS (inductively coupled plasma mass spectrometry) is shown as a very sensitive method for quantitative determination of Th and U concentration and excretion analysis in urine without any sample pretreatment. The current standard method for incorporation monitoring applies alpha-spectrometry, a very tedious and time consuming technique. ICP-MS offers an attractive alternative for monitoring of thorium and uranium body burdens in occupationally exposed subjects and also larger groups of the general population. A limit of determination of 0.5 ng/L in aqueous solutions and 1 ng/L in urine samples for both elements was achieved, with a precision of about ± 10% in the concentration range of appr. 10 ng/L. Due to the lack of a suitable reference material, the accuracy of the method was tested by comparing some of the results with those obtained by -spectrometry, especially for U. There was a sufficient agreement on both results.     

Determination of uranium, thorium and plutonium isotopes by ICP-MS

Quantitative and isotopic measurement of actinide elements is required in many circumstances in the nuclear industry. For example, determination of very low levels of these alpha emitters in human urine samples is used to assess the internal committed dose for nuclear workers. Quantifying actinide isotopes in radioactive waste from nuclear processing and nuclear facility decommissioning provides important information for waste management. Accurate determination of the uranium isotopic ratios in reactor fuels provides fuel burnup information. Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of Th, U, and Pu in various samples including urine, nuclear waste, and nuclear fuel in our laboratory. In order to maximize the capability of the technique and ensure quality analyses, ICP-MS was used to analyze samples directly, or after pre-treatment to separate complicated matrices or to concentrate the analyte(s). High-efficiency sample introduction techniques were investigated. Spectral interferences to minor isotopes caused by peak tails and hydride ions of major actinide isotopes were studied in detail using solutions prepared with light and heavy waters. The quality of the isotopic ratio measurement was monitored using standard reference materials.     

Flow injection extraction chromatography with ICP-MS for thorium and uranium determination in human body fluids

A method based on flow injection extraction chromatography coupled to on-line ICP-MS (FI-EXC-ICPMS) has been developed and validated for simultaneous thorium and uranium determination in human body fluids. By using extraction chromatography, the limits of detection achieved for ²³²Th, ²³⁵U and ²³⁸U were 0.06 ng^.l^-1, 0.0014 ng^.l^-1 and 0.05 ng^.l^-1, respectively. The accuracy of the FI-EXC-ICPMS method was 102.4% and 101.5% with overall precision (RSD_max at 95% CI) of 5.3% and 4.9% for ²³²Th and ²³⁸U, respectively. The ²³⁵U/²³⁸U atom ratio is measured with 1.8% precision. The technique was employed for simultaneous thorium and uranium analyses in human urine and blood samples after microwave digestion. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of uranium, thorium and rare-earth elements in zircon samples using ICP-MS

Zircon is an accessory mineral, which occurs at low concentrations in a wide variety of rocks and is a host for hafnium, rare-earth elements (REE) and radio active elements like uranium and thorium. The presence of uranium in zircon has led to its increased use in the age determination of rocks. Zirconium is also considered as a strategic, hi-tech element because of its various applications, especially in the manufacturing, nuclear and aerospace industries. Analysis of zircon constitutes one of the tough tasks in analytical chemistry as it is a highly resistant mineral and it is extremely difficult to achieve its complete decomposition. In the present work, inductively coupled plasma mass spectrometry has been applied to the determination of hafnium, REE, uranium and thorium in zircon samples using two different sample dissolution procedures, one employing sodium peroxide fusion and another using a fusion mixture of KHF₂ and NaF in 3:1 ratio. Some selected zircon samples originating from different places on the eastern coast of India have been analysed by both the methods and values obtained by both methods were found to be in good agreement with each other. Though a number of international zircon reference materials are available, certified or even proposed values are available only for a very few elements in them. Two zircon reference materials have also been analysed by both methods and usable values have been proposed in this paper. The values obtained by both methods were found to compare well with each other and as well with those reported in literature. The % RSD for all the estimated elements varied from 1.0 to 12.0% at different concentration levels.     

Simultaneous determination of uranium and thorium in high grade thorium ores

A routine procedure has been developed for the simultaneous determination of uranium and thorium in high concentration thorium ores. INAA is used to determine the uranium and thorium concentration. However, for very low concentrations of uranium a radiochemical procedure based on the use of NPy/benzene as an extractant has to be employed. The precision and accuracy of the method has been determined by analyzing IAEA and NBL standard thorium/uranium ores.     

Flow-injection technique for determination of uranium and thorium isotopes in urine by inductively coupled plasma mass spectrometry

A sensitive and efficient flow-injection (FI) preconcentration and matrix-separation technique coupled to sector field ICP–mass spectrometry (SF-ICP–MS) has been developed and validated for simultaneous determination of ultra-low levels of uranium (U) and thorium (Th) in human urine. The method is based on selective retention of U and Th from a urine matrix, after microwave digestion, on an extraction chromatographic TRU resin, as an alternative to U/TEVA resin, and their subsequent elution with ammonium oxalate. Using a 10 mL sample, the limits of detection achieved for ²³⁸U and ²³²Th were 0.02 and 0.03 ng L^–1, respectively. The accuracy of the method was checked by spike-recovery measurements. Levels of U and Th in human urine were found to be in the ranges 1.86–5.50 and 0.176–2.35 ng L^–1, respectively, well in agreement with levels considered normal for non-occupationally exposed persons. The precision obtained for five replicate measurements of a urine sample was 2 and 3% for U and Th, respectively. The method also enables on-line measurements of the ²³⁵U/²³⁸U isotope ratios in urine. Precision of 0.82–1.04% (RSD) was obtained for ²³⁵U/²³⁸U at low ng L^–1 levels, using the FI transient signal approach.     

Direct determination of thorium in uranium oxide by X-ray fluorescence

Summary Thorium in uranium is determined directly at trace levels by an XRF method. Uranium oxide samples are put in the form of double layer pellets and analysed by using Philips PW-1220 X-ray spectrometer. The typical value of the precision of the method at 200 ppm level is ±10% and estimation range is 50–1000 ppm of thorium in uranium.

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Direkte Bestimmung von Thorium in Uranoxid durch Röntgenfluorescenz-Spektrometrie

Zusammenfassung Mit Hilfe der beschriebenen Methode kann Th in Spurenkonzentrationen direkt bestimmt werden. Die Uranoxidproben werden als Doppelschicht-Tabletten eingesetzt und mit Hilfe eines Philips PW-1220 Röntgenspektrometers analysiert. Die Genauigkeit im Bereich von 200 ppm beträgt ±10%. Der Anwendungsbereich liegt bei 50–1000 ppm.

     

Rapid analysis technique for strontium,thorium, and uranium in urine samples

The electronic properties of the metal atoms encaged in a fullerence cage were investigated using synchrotron X-ray photoelectron spectroscopy. Systematic variations in photoemission of valence band of Gd@C₈₂, Gd@C₈₂(OH)₁₂, and Gd@C₈₂(OH)₂₂ were observed in Gd 5p levels. The results suggest that the electronic properties of the inner metal atom can be efficiently modulated by surface chemistry of the fullerene cage.     

Leaching of uranium,radium and thorium from vertisol soil by ground water

Shallow land burial is routinely used for the disposal of low-level radioactive waste. Natural processes causing leaching of radionuclides can lead to contamination of surrounding ground water and soil by the radionuclides. The comparative leachability of radionuclides U_(nat), ²²⁶Ra, ²²⁸Ra and Th_(nat) from the soil of a radioactive waste disposal site, by ground water was evaluated. The probability of leaching was obtained in the following order Ra (≈77%) > U (≈40%) > Th (≈20%). Observed ratios (OR) were calculated to correlate leachability of radionuclides to that of major cations Ca²⁺ and Mg²⁺. The leaching of the radionuclides was seen to be dependent on Ca²⁺ and SO₄²⁻ leached from the soil. This study provides sitespecific leachability of radionuclides, that can be used as indicator of the tendency for migration or retention in soil. It can play an important role during an unforeseen accident like breach of containment at the waste disposal site leading to contamination of soil and ground water and causing hazard to public via drinking water route.     

Determination of uranium and thorium in complex samples using chromatographic separation, ICP-MS and spectrophotometric detection

The paper describes a research of possible application of UTEVA and TRU resins and anion exchanger AMBERLITE CG-400 in nitrate form for the isolation of uranium and thorium from natural samples. The results of determination of distribution coefficient have shown that uranium and thorium bind on TRU and UTEVA resins from the solutions of nitric and hydrochloric acids, and binding strength increases proportionally to increase the concentration of acids. Uranium and thorium bind rather strongly to TRU resin from the nitric acid in concentration ranging from 0.5 to 5 mol L⁻¹, while large quantities of other ions present in the sample do not influence on the binding strength. Due to the difference in binding strength in HCl and HNO₃ respectively, uranium and thorium can be easily separated from each other on the columns filled with TRU resin. Furthermore, thorium binds to anion exchanger in nitrate form from alcohol solutions of nitric acid very strongly, while uranium does not, so they can be easily separated. Based on these results, we have created the procedures of preconcentration and separation of uranium and thorium from the soil, drinking water and seawater samples by using TRU and UTEVA resins and strong base anion exchangers in nitrate form. In one of the procedures, uranium and thorium bind directly from the samples of drinking water and seawater on the column filled with TRU resin from 0.5 mol L⁻¹ HNO₃ in a water sample. After binding, thorium is separated from uranium with 0.5 mol L⁻¹ HCl, and uranium is eluted with deionised water. By applying the described procedure, it is possible to achieve the concentration factor of over 1000 for the column filled with 1 g of resin and splashed with 2 L of the sample. Spectrophotometric determination with Arsenazo III, with this concentration factor results in detection limits below 1 μg L⁻¹ for uranium and thorium. In the second procedure, uranium and thorium are isolated from the soil samples with TRU resin, while they are separated from each other on the column filled with anion exchanger in alcohol solutions. Anion exchanger combined with alcohol solutions enables isolation of thorium from soil samples and its separation from a wide range of elements, as well as spectrophotometric determination, ICP-MS determination, and other determination techniques.     

A titrimetric method for the sequential determination of thorium and uranium

A method for the sequential determination of thorium and uranium has been developed. In the sample solution containing thorium and uranium, thorium is first determined by complexometric titration with ethylenediaminetetraacetic acid (EDTA) and then in the same solution uranium is determined by redox titration employing potentiometry. As EDTA interferes in uranium determination giving positive bias, it is destroyed by fuming with HClO₄ prior to the determination of uranium. A precision and accuracy of better than ±0.15% is obtained for thorium at 10mg level and uranium ranging from 5 mg to 20 mg in the aliquot.     

A simple method for the determination of uranium and thorium by delayed neutron counting

A simple method for the determination of uranium and thorium by delayed neutron counting is described. One portion of the sample is irradiated in a reactor and the delayed neutrons are counted. Another portion of the sample is mixed with B₄ C powder absorbing the thermal neutrons, and irradiated in the same position. From those data, both uranium and thorium can be calculated when a quantitative calibration has been made beforehand. The detection limits for the pure elements are 0.07 ppm for uranium and 2 ppm for thorium with the minimum analyzing time being 2 min. The accuracy of the method is investigated by comparing results obtained by the method described here with results obtained by epithermal activation analysis.     

Separation and determination of uranium and thorium in zircon sands by extraction chromatography

An extraction chromatography method with a column of microporous polyethylene supporting tri-n-octylamine /TNOA/ was used to separate uranium and thorium from zircon sands. The two elements were determined both by physical-chemical techniques /fluorimetry and colorimetry/ and by radiometric techniques /alpha spectrometry/ after electrodeposition: their respective contents agreed well; furthermore, uranium and thorium isotopes resulted in secular equilibrium in the analyzed material.     

Separation and spectrophotometric determination of thorium contained in uranium concentrate

A method for the determination of thorium in uranium concentrate by spectrophotometry with Arsenazo III has been developed. Preliminary solvent extraction procedures were used to eliminate interfering species. Samples were dissolved in nitric, perchloric and sulfuric acid and the uranium extracted from the solution using tri-octylamine. The aqueous layer was evaporated to dryness and the residue re-dissolved with hydrochloric acid, thorium was extracted by tri-n-octyl phosphine oxide and stripped with oxalic acid. For a typical uranium concentrate produced from the phosphate rock of Itataia, Brazil, concentrations of thorium as low as 5 g·g^-1 can be determined.     

Biamperometric methodology for sequential determination of thorium and uranium

A biamperometric methodology for the sequential determination of thorium (Th) and uranium (U) was developed. In the sample solution containing Th and U, Th was first determined by complexometric titration based on the electrochemical behaviour of EDTA maintaining a potential of ≥200 mV between the twin Pt electrodes. This was followed by the redox titrimetric determination of U employing biamperometry to detect the end point. Prior to the determination of U, EDTA was destroyed by fuming with concentrated HClO₄ to eliminate its interference in the U determination. The method was tested for the determination of Th and U in (Th, U) O₂ samples containing 4 mg of Th and 2–8 mg of U, with precision and accuracy of better than 0.3 %.     

Simultaneous determination of uranium and thorium with Arsenazo III by second-derivative spectrophotometry

A derivative spectrophotometric method has been developed for the simultaneous determination of microgram quantities of uranium and thorium with Arsenazo III in hydrochloric acid medium. The second-derivative absorbances of the uranium and thorium Arsenazo III complexes at 679.5 and 684.4 nm are used for their quantification. Uranium and thorium, both in the range 0.1-0.7 mug/ml have been determined simultaneously with good precision. The procedure does not require separation of uranium and thorium, and allows the determination of both metals in the presence of alkaline-earth metals and zirconium, but lanthanides interfere.     

Simultaneous determination of trace uranium and thorium by radiochemical neutron activation analysis

A method for the simultaneous, radiochemical neutron activation analysis of uranium and thorium at trace levels in biological materials is described, based on a technique known as LICSIR, in which a double neutron irradiation is employed. In the first, long irradiation²³³Pa (27.0 d) is induced by neutron capture on²³²Th and then the sample is cooled for several weeks. A second short irradiation to induce²³⁹U (23.5 m) is followed by a rapid sequential radiochemical separation by solvent extraction of²³⁹U with TBP and²³³Pa with TOPO. Chemical yields of²³⁹U and²³³Pa were measured for each sample aliquot using added²³⁵U and²³¹Pa tracers from the -spectra of the separated fractions. The technique was validated by quality control analyses.     

A scheme for sequential separation of thorium,lanthanides, uranium in geo-materials and their ICP-OES determination

Journal of Radioanalytical and Nuclear Chemistry - Neutral complexes of thorium and lanthanides with 2,3-dihydroxynaphthalene and anionic complexes of uranium with the same chelating agent in...     

Feasibility of ICP-MS for the assessment of uranium excretion in urine

Inductively coupled plasma mass spectrometry (ICP-MS) has been applied to the assessment of urinary uranium excretion in non-exposed subjects. The sensitivity of the method is high enough to determine²³⁸U concentration in unprocessed urine in any subject. Data obtained so far show a significant increase of²³⁸U excretion with age and no differences between males and females.     

A neutron activation analysis procedure for the determination of uranium,thorium and potassium in geologic samples

A neutron activation analysis procedure was developed for the determination of uranium, thorium and potassium in basic and ultrabasic rocks. The three elements are determined in the same 0.5-g sample following a 30-min irradiation in a thermal neutron flux of 2·10¹² n·cm^?2·sec^?1. Following radiochemical separation, the nuclides²³⁹U (T=23.5 m),²³³Th (T=22.2 m) and⁴²K (T=12.36 h) are measured by β-counting. A computer program is used to resolve the decay curves which are complex owing to contamination and the growth of daughter activities. The method was used to determine uranium, throium and potassium in the U. S. Geological Survey standard rocks DTS-1, PCC-1 and BCR-1. For 0.5-g samples the limits of detection for uranium, throium and potassium are 0.7, 1.0 and 10 ppb, respectively.