Direct Determination Of Uranium Research Articles

Direct Detection of Uranyl in Urine by Dissociation from Aptamer-Modified Nanosensor Arrays.

An ever-growing demand for uranium in various industries raises concern for human health of both occupationally exposed personnel and the general population. Toxicological effects related to uranium (natural, enriched, or depleted uranium) intake involve renal, pulmonary, neurological, skeletal, and hepatic damage. Absorbed uranium is filtered by the kidneys and excreted in the urine, thus making uranium detection in urine a primary indication for exposure and body burden assessment. Therefore, the detection of uranium contamination in bio-samples (urine, blood, saliva, etc.,) is of crucial importance in the field of occupational exposure and human health-related applications, as well as in nuclear forensics. However, the direct determination of uranium in bio-samples is challenging because of "ultra-low" concentrations of uranium, inherent matrix complexity, and sample diversity, which pose a great analytical challenge to existing detection methods. Here, we report on the direct, real-time, sensitive, and selective detection of uranyl ions in unprocessed and undiluted urine samples using a uranyl-binding aptamer-modified silicon nanowire-based field-effect transistor (SiNW-FET) biosensor, with a detection limit in the picomolar concentration range. The aptamer-modified SiNW-FET presented in this work enables the simple and sensitive detection of uranyl in urine samples. The experimental approach has a straight-forward implementation to other metals and toxic elements, given the availability of target-specific aptamers. Combining the high surface-to-volume ratio of SiNWs, the high affinity and selectivity of the uranyl-binding aptamer, and the distinctive sensing methodology gives rise to a practical platform, offering simple and straightforward sensing of uranyl levels in urine, suitable for field deployment and point-of-care applications.

Comparison of four analytical techniques for determining uranium in different rock samples

Four different analytical techniques were compared for their performance in direct determination of uranium in seven rock samples. These methods include: ion chromatography, laser fluorimetry, UV–Vis spectrophotometry and gamma spectrometry. The samples under study were six ore samples beside an international reference sample (GBWO4115). The results obtained from the comparison study reported a method accuracy of 98%, 90%, 65% and 86% for ion chromatography, laser fluorimetry, UV–Vis spectrophotometry and gamma spectrometry techniques respectively. Also, on the converse of the other three techniques, ion chromatography technique using DX-500 ion chromatograph achieves superior agreement with the certified sample with only 2% bias.

Direct determination of uranium in sintered deeply depleted uranium oxide pellets by wavelength dispersive X-ray fluorescence spectrometry

This paper presents studies on direct non-destructive determination of uranium in sintered deeply depleted (DD) uranium oxide (UO2) pellets by wavelength dispersive X-ray fluorescence (WDXRF) spectrometry. A special collet was designed and fabricated for holding the sintered DDUO2 pellets for direct analysis, thus avoiding the sample preparation steps. The samples were analyzed using a calibration plot obtained from WDXRF spectra of matrix matched calibration standards. The WDXRF determined uranium values were found to be in very close agreement with titrimetric values and has reproducibility better than 0.05% (RSD, 1 s, n = 10) for the sintered DDUO2 pellets having U: 86.81–88.04 wt%.

Comments on: Studies on Effective Decomposition of Monazite Minerals by Variety of Phosphate Fluxes for Simple and Direct Determination of Uranium by LED Fluorimeter

This paper presents my comment on the published article, studies on effective decomposition of monazite minerals by variety of phosphate fluxes for simple and direct determination of uranium by LED Fluorimeter. Monazite is a refractory REE-mineral. These REE-bearing minerals contain inclusions of monazite/xenotime. The findings have previously published elsewhere without proper cross referencing /justification in the cited manuscript. It constitutes citation manipulation including plagiarism as well as scientific misconduct. A separate publication and claim by authors dealing with uranium determination in monazite by pulsed fluorimetry (LED fluorimeter) has no novelty/ originality/improvements in the manuscript. Monazite sample decomposition using concentrated sulphuric will be the best option for uranium measurement in such matrices using laser/LED fluorimetry, as it eliminates matrix matching of calibration standards.

Direct determination of uranium and thorium in minerals by time-of-flight mass spectrometry with pulsed glow discharge

A direct method of uranium and thorium determination in non-conducting geological samples using time-of-flight mass spectrometry with pulsed glow discharge was proposed.

Studies on effective decomposition of monazite minerals by variety of phosphate fluxes for simple and direct determination of uranium by LED fluorimeter

Studies on effective decomposition of monazite minerals by variety of phosphate fluxes for simple and direct determination of uranium by LED fluorimeter

Rapid and interference free determination of ultra trace level of uranium in potable water originating from different geochemical environments by ICP-OES

Direct determination of uranium in the concentration range of 8 μg L−1 to mg L−1 in water samples originating from different geochemical environments has been done using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Uranium detection with 2–3% RSD (relative standard deviation) has been achieved in water samples by optimizing the plasma power, argon and sheath gas flow. These parameters were optimized for three different emission lines of uranium at 385.958, 409.014 and 424.167 nm. Interference arising due to the variation in concentration of bicarbonate, sodium chloride, calcium chloride, Fe and dissolved organic carbon (DOC) on the determination of uranium in water samples was also cheeked as these are the elements which vary as per the prevailing geochemical environment in groundwater samples. The concentration of NaHCO3, CaCl2 and NaCl in water was varied in the range 0.5–2.0%; whereas Fe ranged between 1 and 10 μg mL−1 and DOC between 0.1–1%. No marked interference in quantitative determination of uranium was observed due to elevated level of NaHCO3, CaCl2 and NaCl and Fe and DOC in groundwater samples. Concentration of uranium was also determined by other techniques like adsorptive striping voltametry (AdSv); laser fluorimetry and alpha spectrometry. Results indicate distinct advantage for uranium determination by ICP-OES compare to other techniques.

Direct determination of uranium in seawater by laser fluorimetry

A method for estimation of uranium in seawater by using steady state laser flourimetry is described. Uranium present in seawater, in concentration of approximately 3 ng ml −1 was estimated without prior separation of matrix. Quenching effect of major ions (Cl −, Na +, SO 4 −, Mg +, Ca +, K +, HCO 3 −, Br −) present in seawater on fluorescence intensity of uranium was studied. The concentration of phosphoric acid required for maximum enhancement of fluorescence intensity was optimized and was found to be 5%. Similarly the volume of concentrated nitric acid required to eliminate the quenching effect of chloride and bromide completely from 5 ml of seawater were optimized and was found to be 3 ml. A simple equation was derived using steady state fluorescence correction method and was used for calculation of uranium concentration in seawater samples. The method has a precesion of 1% (1 s, n = 3). The values obtained from laser fluorimetry were validated by analyzing the same samples by linear sweep adsorptive stripping voltametry (LSASV) of the uranium–chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) complex. Both the values are well in agreement.

Direct and fast uranium determination in zirconium by time-resolved laser-induced fluorescence spectrometry

Fast and direct determination of uranium in zirconium is required for nuclear process control. Time-resolved laser-induced fluorescence spectrometry is a very selective and sensitive method that has been largely used for uranium(VI) analysis in the nuclear fuel cycle. Due to the very low quenching constant of zirconium, the uranyl fluorescence signal is weakly affected by this element. By using direct fluorescence signal measurement, the uranium concentration is obtained in less than a minute and the limit of detection is close to 10 ng 1 −1 which corresponds to 1 ng g −1 relative to the zirconium matrix. Moreover, the zirconium dissolution medium (nitric/hydrofluoric acid) is complexing enough to allow direct measurement with no use of other complexing reagent. Such procedure can also be used for uranium determination in hafnium.

二重収束型高分解能誘導結合プラズマ質量分析装置による隆水中のウランの直接分析

二重収束型高分解能誘導結合プラズマ質量分析装置による隆水中のウランの直接分析

Direct Determination of Uranium in Seawater by Absorption Spectrophotometry

Direct Determination of Uranium in Seawater by Absorption Spectrophotometry

Investigation of the direct determination of uranium in plasma and urine by inductively coupled plasma mass spectrometry

Investigation of the direct determination of uranium in plasma and urine by inductively coupled plasma mass spectrometry

Direct determination of uranium in water by cathodic stripping voltammetry

Direct determination of uranium in water by cathodic stripping voltammetry

Spectrophotometric method for the direct determination of uranium in carbonate solution

A spectrophotometric method for direct determination of uranium in carbonate solution has been developed. No extraction or decomposition steps are necessary. The highly sensitive (4-2-pyridylazo) resorcinol, as well as 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, producing very stable uranium(VI) complexes, were used for its spectrophotometric determination.

Spectrophotometric determination of uranium(VI) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in a flow-injection system

The direct determination of uranium(VI) by a flow-injection procedure is based on spectrophotometric measurement with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the present of fluoride. The interfering effects of many commonly occuring elements were studied. The calibration curve was linear over the range 0.5–20 mg 1 −1 uranium(VI). The relative standard deviation obtained on a leach liquor containing 10 mg 1 −1 uranium(VI) was 1.9%. The procedure is rapid and convenient, and up to 40 samples can be analysed per hour.

Determination of low uranium concentration in carbonate-bicarbonate solutions by X-ray fluorescence

A method has been developed for the direct determination of uranium in carbonate solutions by X-ray fluorescence. Uranium, in the concentration range 0.2–50 ppm, is first absorbed as the carbonate complex on an anion exchange resin and then determined by X-ray fluorescence. A sensitivity corresponding to 20 ppb in 250 ml solution and a precision of ±6.5% was obtained. The sensitivity was 100-fold greater than that obtained by the direct determination in solution by X-ray fluorescence.

A polarographic method for the direct determination of uranium(Vl) in trialkylamine sulphate extracts

A polarographic method for the direct determination of uranium(Vl) in trialkylamine sulphate extracts

The direct determination of uranium in concentrates by spectrophotometric titration with ferric sulphate

Summary A direct method is presented for the determination of uranium in concentrates by spectrophotometric titration with ferric sulphate, after a bismuth amalgam reduction. The oxidation of U(IV) by Fe(III) was found to be rapid and complete at room temperature, under suitable conditions. Copper, molybdenum and vanadium interfere to some extent, and their maximum permissible concentrations are discussed. A complete determination may be carried out in little over an hour with a precision of 2–3 parts per thousand. An Uvispek spectrophotometer was adapted for spectrophotometric titrations without modification of the instrument.

The direct determination of uranium in concentrates by spectrophotometric titration with ferric sulphate

The direct determination of uranium in concentrates by spectrophotometric titration with ferric sulphate