Determination Of Uranium In Water Research Articles

Serious interference of dissolved organic compounds in the laser induced fluorimetric determination of uranium in water: a selective & sensitive method for the laser induced fluorimetric determination of uranium in water

In this report, serious negative interference of Dissolved Organic Compounds (DOCs) in the laser/LED fluorimetric determination of uranium in natural and waste waters has been amply demonstrated.

Determination of uranium in aqueous solutions by the time-of-flight mass-spectrometry with a pulsed glow discharge after its accumulation on the oxidized carbon nanotubes

The pollution of the environment with uranium dictates the need to control the concentration of this element in natural waters to the permissible limits for the stability of the ecosystems and public health. In 2011, WHO set maximum permissible concentration of uranium in water to 0.03 ppm due to the strong toxicity and radioactivity of uranium in water. Therefore, the continuous monitoring of uranium content is an important task for the safety and health of the citizens. To determine the low uranium content in natural waters, the conservation of the studied solutions is necessary. However, this method of storage and transportation is not always simple. In the current paper, as a convenient method of concentrating uranium, preserving the sample and transporting it, we used the method of sorbing uranium on sorbents. Single-layer carbon nanotubes were used as sorbents. Their surfaces were modified using wet chemical oxidation and synthesis with Aerosil A-380 silica. Two schemes were considered for concentrating the uranium on the surface of the sorbent: individual carbon nanotubes and nanotubes modified with silica. The direct analysis was used to determine the content of uranium in the sorbent, namely, time-of-flight mass spectrometry with the pulsed glow discharge (GDMS). The most effective approach for the determination of uranium in water was the sorption of uranium on the tablet consisting of oxidized nanotubes modified with silica. The limit of detection in this case was 0.2 ppb. Keywords : mass-spectrometry, pulsed glow discharge, environment, direct analysis, uranium, carbon nanotubes DOI: http://dx.doi.org/10.15826/analitika.2020.24.2.001 T itova A.D 1 , Postnov V.N. 1 , Savinov S.S. 1 , Stolyarova N.V. 2 , Ivanenko N.B. 2 , Chuchina V.A. 1 , Gubal A.R. 1 , Ganeev A.A. 1,2 1 Saint-Petersburg State University (SPBU), Universitetskaya emb., 7/9, Saint-Petersburg, 199034, Russian Federation 2 Institute of Toxicology of Federal Medico-Biological Agency, ul. Bekhtereva, 1, Saint-Petersburg, 192019, Russian Federation

Trace determination of uranium preconcentrated using graphene oxide by total reflection X‐ray fluorescence spectrometry

A new method based on dispersive microsolid phase extraction using graphene oxide (GO) as a solid adsorbent and total reflection X‐ray fluorescence (TXRF) spectrometry is proposed for trace determination of uranium. In the developed methodology, a suspension of GO was injected into uranium‐spiked multielement solutions including rubidium; after filtration, the membrane filter with collected GO was placed in a small volume of internal standard acid solution and the eluent containing uranium was deposited onto a fluorine resin‐coated slide glass, which is a disposable sample stage. Using GO was effective for removal of rubidium from the measurement solution to avoid interference between Rb Kα peak and U Lα peak. The high enrichment factor of 150 enables obtaining uranium detection limits of 0.042, 0.087, and 0.12 μg L−1 for ionic strength of 0.01, 0.1, and 1 mol L−1, respectively. Such low detection limits were obtained by using a benchtop TXRF spectrometer with 5‐min measurement. The proposed method is suitable for trace uranium determination in water, including high salinity samples.

Optimization of the arsenazo-III method for the determination of uranium in water and plant samples

This work reports a reliable, fast and optimized photometric technique based on the specific chemical complexation of uranyl ion with arsenazo-III. In the case of solid samples (plant samples), for which mineralization under acidic and oxidative conditions was used, addition of ascorbic acid led to stabilization of the arsenazo–uranyl complex over time. The results, in total agreement with data obtained from α and γ spectrometries, demonstrate that the present technique is able to precisely quantify uranium in water as well as in plant samples, within the μg/L and mg/g ranges respectively.

Determination of uranium in water based on enzyme inhibition using a wireless magnetoelastic sensor

The aim of this paper is to develop a wireless magnetoelastic sensing method for the determination of uranium in water based on the inhibitory effect of uranyl cation to α-amylase. In this method, a wireless sensor used for detecting uranium was fabricated by immobilizing a layer of starch gel on the surface of a magnetoelastic foil. When the sensor was in a solution containing α-amylase, the α-amylase catalyzed the hydrolyzation of starch, causing a resonance frequency shift of the sensor. Meanwhile, the catalytic hydrolyzation of starch was inhibited by uranium presented in the above solution, resulting in a decrease in the resonance frequency shift of the sensor. Consequently, the amount of uranium could be determined by measuring the resonance frequency shift. The influence of manifold variables on the determination was investigated in details. A linear range was found to be 9.2 to 103.5 µg L−1 under optimal conditions with a detection limit of 3.6 µg L−1. The method was applied to the determination of uranium in environmental water samples with satisfactory results.

Application of different types of resins in the radiometric determination of uranium in waters

The aim of this study is to compare different resins regarding their separation and pre-concentration efficiency for uranium from aqueous solutions and its subsequent radiometric determination by liquid scintillation counting (LSC). The different types of the investigated resins include: (a) a pure cation-exchange resin (Dowex Marathon C), (b) a complex forming resin (Chelex 100) and (c) an impregnated resin (5% diethylene glycol succinate on Chromosorb W-H). The radiometric measurements were performed after mixing of the pre-concentrated aqueous phase with the liquid scintillation cocktail. The effect of experimental conditions such as pH, salinity (e.g. [NaCl]) and the presence of other chemical species (e.g. Ca2+ and Fe3+ ions or humic acid and silica colloids) on the separation recovery have been investigated at constant uranium/radioactivity concentration. According to the experimental results the maximum chemical recovery differs significantly from one resin to another as a function of either, pH or the other chemical parameters. The optimum pH is found to be 8, 4 and 8 for Marathon C, Chelex-100 and diethylene glycol succinate, respectively. On the other hand, generally Ca2+ and Fe3+ ions as well as the presence of colloidal species in solution (even at low concentrations) result in a significant decrease of the chemical recovery of uranium, particularly for Marathon C and the diethylene glycol succinate impregnated resins. Generally, among the studied resins Chelex 100 was superior regarding chemical recovery, selectivity, regeneration and reuse.

Uranium determination in water samples by liquid scintillation counting after cloud point extraction

The aim of this study is the radiometric determination of uranium in waters by liquid scintillation counting (LSC) after pre-concentration of the element by cloud point extraction (CPE). For CPE, tributyl phosphate (TBP) is used as the complexing agent and (1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol (Triton X-114) as the surfactant. The measurement is performed after phase separation by mixing of the surfactant phase with the liquid scintillation cocktail. The effect of experimental conditions such as pH, reactant ratio (e.g. m(TBP)/m(Triton), ionic strength (e.g. [NaCl]) and the presence of other chemical species (e.g. Ca2+ and Fe3+ ions as well as humic acid and silica colloids) on CPE has been investigated. According to the experimental results the total method efficiency is (13 ± 2)% and the chemical recovery (50 ± 10)% at pH 4 and reactant ratio (V(TBP)/V(Triton) = 0.1). Regarding the other parameters, generally Ca2+ and Fe3+ ions as well as the presence of colloidal species in solution (even at low concentrations) results in significant decrease of the chemical recovery of uranium. On the other hand increasing NaCl concentration leads to enhancement of chemical recovery. The detection limit under optimum experimental conditions has been found to be 0.5 Bq L−1 indicating that the method could be applied only to waters samples with increased uranium concentration. Moreover, the negative effect of the chemical species found in natural waters limits the applicability of the method with the respect to environmental radioactivity measurements.

An online preconcentration system for the determination of uranium in water and effluent samples

Amberlite XAD-4 resin functionalized with β-nitroso-α-naphthol was applied to an online system for the preconcentration and determination of uranium. U (VI) ions were retained on the minicolumn at an appropriate pH and then desorbed with acid solution. The amount of uranium in the eluate was measured spectrophotometrically at 650 nm using Arsenazo III as a colorimetric reagent. The limit of detection and the preconcentration factor were 1.8 μg L(-1) and 10, respectively. The chemical and flow variables affecting the preconcentration were studied. The influence of several ions on the system was also investigated. The method was successfully applied for the evaluation of uranium in water and in effluent samples.

Determination of Uranium in Water Accumulated in the Shelter by the X-Ray Fluorescence Method

A procedure was developed for determining U in LRW of the Shelter, involving isolation of U in the form of a solid “thin” source (density under 5 mg cm−2) on a neutral substrate, suitable for direct X-ray fluorescence analysis. An optimal system was chosen for concentrating microamounts of U by isolation on standard membrane filters from dilute aqueous solutions in the form of complexes with 1-(2-thiazolylazo)-2-naphthol (TAN). The procedure was tested with real LRW samples taken inside the Shelter.

Determination of uranium in water by neutron activation and a low energy photon spectrometer

Ground and drinking water samples were analyzed for uranium by neutron activation analysis and a low energy photon spectrometer. Two methods were used: direct irradiation of water and pre-concentration by evaporation. The concentrations varied from 0.1 to 21 µg/l. The lowest detection limit obtained by pre-concentration was 0.01 µg/l while for the direct irradiation of water it was 0.04 µg/l. With these methods, we were able to determine the U concentration in all samples which were submitted for analysis.

Comparison of different methods for uranium determination in water

Photometry, laser photometry, liquid scintillation (LSC), gamma spectrometry and alpha spectrometry were used for estimating waterborne uranium concentration. The chemical procedures applied were pre-concentration, liquid extraction, chromatographic resin extraction and precipitation. Our results show that laser photometry is an easy and accurate method capable of estimating low uranium concentrations, parts of micrograms per litre. It is not applicable for higher concentrations, difficult water matrixes and isotope determination. The classical photometry is complementary, resolving the problem related to high concentrations, practically up to 10 mg/l. Alpha and gamma spectrometry resolve the problem of precise isotope determination, but with the disadvantage of hard chemical preparation and long measurement times. An intermediate method is LSC, with the problem of isotope estimation, due to poor energy resolution.

Preconcentration of trace amounts of uranium in water samples on octadecyl silica membrane disks modified by bis(2-ethylhexyl) hydrogen phosphate and its determination by alpha-spectrometry without electrodeposition

A simple and reliable method for the selective extraction and determination of uranium in water using octadecyl-bonded silica membrane disks modified with bis (2-ethylhexyl) hydrogen phosphate and alpha-spectrometry is described. Extraction efficiency and influence of sample matrix, optimum amount of extractant, type and minimum amount of organic eluent and flow rates were evaluated. The limit of detection of the proposed method is 40 ng per 1000 ml. The influence of potential interfering cations in water samples on the recovery of U(VI) was investigated. The method was successfully applied to the extraction and determination of uranium in natural water.

On-Line Trace Enrichment and Determination of Uranium in Waters by Flow Injection Inductively Coupled Plasma Mass Spectrometry

A flow injection system incorporating a microcolumn of activated alumina was combined with inductively coupled plasma mass spectrometry for on-line trace enrichment and determination of uranium in surface waters and sea water. Deposition of uranium was effected with the use of a basic alumina microcolumn, and injection of nitric acid (250 μL, 2M) served to elute retained species to the ICP. A sample volume of 14 mL resulted in a preconcentration factor of 40, and precision at the 50-ng 1−1level was 4.5% (RSD). The procedure was applied to mineral waters, river water, and sea water, and accuracy was assessed through either analysis of certified reference waters or recovery experiments.

A computerized spark counter

This paper describes a computerized spark counter used for the determination of uranium in water. By using a solution D2000 to distribute uranium-containing residues from drops of water and a special circuit to prevent possible smaller spark pulse from following a normal one, a reproducibility of 3 per cent, a detection limit of 5×10-12 and an analysis speed of 1 sample per two or three minutes is reached.

Atomic Absorption Spectrometric and Spectrophotometric Trace Analysis of Uranium in Environmental Samples with N-p-MEthoxyphenyl-2-Furylacrylohydroxamic acid and 4-(2-Pyridylazo) Resorcinol

Abstract Methods are presented for the determination of uranium in presence of various anions and cations which are usually associated with it in rocks, waters, minerals, nuclear fission products and biological materials. The methods are based on the solvent extraction of uranium(VI) as its complex with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform, or methyl isobutyl ketone (MIBK) at pH 4.5–5.1. The uranium in the orange-yellow chloroform extract is either directly determined spectrophotometrically or back-extracted into 0.01 M HCl solution and determined as its intensely red coloured complex (ϵ = 3.94 × 104 mol−1 cm−1 at 530 nm) with 4-(2-Pyridylazo) resorcinol (PAR). The metal in the MIBK extract is determined atomic absorption spectrometrically by the aspiration of the extract in nitrous oxide-acetylene flame and measuring the absorbance at 358.5 nm resonance line. Both the methods are highly sensitive and selective, and were applied to the determination of uranium in waters, plants and animal tissues.

Direct determination of uranium in water by cathodic stripping voltammetry

Direct determination of uranium in water by cathodic stripping voltammetry

Observations on the Determination of Uranium in Waters by Direct Current Argon Plasma Emission Spectrometry

Abstract This paper reports observations on the determination of uranium in ground and mine waters by direct current argon plasma emission spectrometry. An enhancement effect due to different concentrations of six sodium salts and calcium nitrate was characterized. When the salt concentration of the waters was greater than the aqueous uranium standards, an erroneous uranium signal was found. The method of standard additions showed that direct calibration with aqueous uranium standards containing 0.05M sodium acetate was satisfactory. The use of matrix matched uranium standards is recommended to compensate for large enhancements in the uranium emission signal that may result from the presence of naturally occurring salts. Concentrations of uranium in ground waters ranged from 5 ppm to 16 ppm depending on sampling site and in mine waters from 2 ppm to several hundred ppm.

Uranium determination in water using solid state nuclear track detectors

ABSTRACT A method for detecting low concentrations of Uranium in water is presented in this work. A CR-39 is used as detector, and as a process a consecutive preetching and an electrochemical etching. Concentration measurement of 1 p.p.m. are obtained with out the requirement of a neutron flux. The results show high sensitivity and reproducibility, with a linear response as a function of uranium contents in the water. Therefore, this technique results suitable for measuring of uranium concentrations in rivers lakes, water springs, etc.

Discharge counter for the determination of uranium in water by the fission track method

The circuit and mechanical design of a counter for electrical discharges through fission tracks etched through 10-μm Kimfol and a system for distributing uranium-containing residues from drops of water evaporated on Lexan disks which are covered with Kimfol and irradiated with neutrons are described. The resulting system is used to measure (0.1–10) ×10−9 of U in natural waters and would be able to measure at least 5×10−11 and produce 100–200 analyses per person per day.

Determination of uranium in natural waters after anion-exchange separation

A method is described for the determination of uranium by fluorimetry and spectrophotometry in samples of natural non-saline waters. After acidification with hydrochloric acid, the water sample is filtered and, following the addition of ascorbic acid and potassium thiocyanate, passed through a column of the strongly basic anion-exchange resin Dowex 1-X8 (thiocyanate form). On this exchanger uranium is adsorbed as an anionic thiocyanate complex. After removal of iron and other coadsorbed elements by washing first with a mixture consisting of 50 vol.% tetrahydrofuran, 40 vol.% methyl glycol and 10 vol.% 6 M hydrochloric acid, and then with pure aqueous 6 M hydrochloric acid, the uranium is eluted with 1 M hydrochloric acid. In the eluate, uranium is determined fluorimetrically or by means of the spectrophotometric arsenazo III method. The procedure was used for the routine determination of uranium in water samples collected in Austria.