Application of fission track technique for estimation of uranium concentration in drinking waters of Punjab

Drinking water samples were collected from four different districts, namely Bhatinda, Mansa, Faridkot and Firozpur, of Punjab for ascertaining the U(nat.) concentrations. All samples were preserved, processed and analyzed by laser fluorimetry (LF). To ensure accuracy of the data obtained by LF, few samples (10 nos) from each district were analyzed by alpha spectrometry as well as by fission track analysis (FTA) technique. For FTA technique few μl of water sample was transferred to polythene tube, lexan detector was immersed in it and the other end of the tube was also heat-sealed. Two samples and one uranium standard were irradiated in DHRUVA reactor. Irradiated detectors were chemically etched and tracks counted using an optical microscope. Uranium concentrations in samples ranged from 3.2 to 60.5 ppb and were comparable with those observed by LF.     

Estimation of uranium in geological rock samples by beta–gamma method and its comparison with pellet fluorimetry method

Geological rock samples collected from Narwapahar uranium mines, UCIL, Jaduguda were analysed for the estimation of uranium concentration (U₃O₈) by beta–gamma method which is a physical technique and same set of samples were analysed by pellet fluorimetry technique which is a chemical technique. 28 samples were analysed by beta–gamma method and values varied between 240 and 2,500 ppm. Samples were analysed by pellet fluorimetry and values varied between 260 and 2,300 ppm. The results obtained were well comparable by both the techniques.     

Advances in technologies for the measurement of uranium in diverse matrices

An overview of the advances in technologies, which can be used in the field as well as in a laboratory for the measurement of uranium in diverse matrices like, waters, minerals, mineralized rocks, and other beneficiation products for its exploration and processing industries is presented. Laser based technologies, ion chromatography, microsample X-ray analysis method followed by energy dispersive X-ray fluorescence technique (MXA-EDXRF), sensors for electrochemical detection followed by cyclic voltammogram and alpha liquid scintillation counting techniques are the most promising techniques. Among these techniques, laser fluorimetry/spectrofluorimetry, in particular, is the technique of choice because of its high performance qualification (PQ), inherent sensitivity, simplicity, cost effectiveness, minimum generation of analytical waste, rapidity, easy calibration and operation. It also fulfills the basic essential requirements of reliability, applicability and practicability (RAPs) for the analysis of uranium in solution of diverse matrices in entire nuclear fuel cycle. A very extensive range of uranium concentrations may be covered. Laser fluorimetry is suitable for direct determination of uranium in natural water systems within the μg L⁻¹ and mg L⁻¹ range while differential technique in laser fluorimetry (DT-LIF) is suitable for mineralized rocks and concentrates independent of matrix effects (uranium in samples containing >0.01% uranium). The most interesting feature of TRLIF is its capability of performing speciation of complexes directly in solution as well as remote determination via fiber optics and optrode. Future trend and advances in lasers, miniaturization and automation via flow injection analysis (FIA) has been discussed.     

Determination of uranium concentration in urine of workers in an Iraqi phosphate mine and fertilizer plants

Precise determination of uranium concentration in human urine is quite important in assessment of occupational and public exposure to uranium. In the present work, a pulsed dye nitrogen laser-induced kinetic phosphorescence analysis (KPA) was used to determine uranium in urine of Iraqi phosphate mine and fertilizer plant workers and in the population living near the mining region. A total of 92 urine samples were collected from workers of the Akashat phosphate mine, the Al-Qaim fertilizer complex, and the Akashat residential region. Uranium concentration in urine of all samples ranged between 0.49 to 5.26 μg L^?1 with a total average of 1.47 ± 0.01 μg L^?1. For comparison, all samples were also analyzed using a completely different technique; the nuclear fission track analysis using CR-39 SSNTD. Both techniques were capable of such measurements, although not with an equal degree of uncertainty. KPA technique is found to be more suitable for analysis of urine samples having high concentrations of uranium.     

Presentation of differential laser-induced fluorimetry as a reference measurement procedure for determination of total uranium content in ores and similar matrices

The metrological principle of ‘differential technique in laser-induced fluorimetry’ analysis is discussed and recommended as a reference measurement procedure for determination of total uranium content in ores and similar matrices. The estimated relative expanded uncertainty values obtained for uranium content in standard IAEA samples are, S 1, 0.04 g/kg, S 2, 0.06 g/kg, S 3, 0.04 g/kg, and for S 4, 0.10 g/kg, respectively. These low uncertainty values obtained for uranium show high metrological quality of differential technique. This reference measurement procedure guarantees the quality of an analytical result (accuracy, high precision, reliability, comparability, and traceability). Laser-induced fluorimetry will be useful for the analysis of uranium in ores, certification of reference materials, borehole core assay, and other diverse applications in nuclear fuel cycle. Differential technique in spectrophotometry/laser fluorimetry has inherent high metrological quality. In principle, laser-induced fluorimetry is an ideal technique for the very accurate determination of uranium by the use of appropriate fluorescence-enhancing reagents and methodology depending upon the concentration of uranium and sample matrices.     

Uranium concentration measurements in human blood for some governorates in Iraq using CR-39 track detector

The sensitive and simple technique of fission track etch has been applied to determine trace concentration of uranium in blood samples for occupational and non-occupational workers, male and female, using CR-39 track detector that is employed for registration of induced fission tracks. The results show that the highest recorded uranium concentration in human blood of workers in the ministry of Science and Technology were 1.90 ppb (male, 36 years old, 12 years' work experience, and living in Basrah governorate) and minimum concentration 0.26 ppb (female, 40 years old, 10 years' work experience, and living in Baghdad), while for non-occupational worker, the maximum uranium concentration was 1.76 ppb (female, 63 years old, and living in Al-Muthana) and minimum concentration was 0.28 ppb (female, 20 years old, and living in Baghdad). It has also been found that the uranium concentration in human blood samples of workers in the ministry of Science and Technology are higher than those of non-occupational workers, and the uranium concentrations for female workers and for non-occupational workers were higher than those for male workers and non-occupational workers.     

Determination of uranium at ultratrace levels by time-resolved laser fluorimetry

Uranium at ultratrace levels in the pelleted cake from a NaF/Na₂CO₃/K₂CO₃ (10:45:45) fusion is determined by laser fluorimetry. Light scattering and fluorescence from impurities are greatly reduced by time-resolved fluorimetry. The optimum excitation wavelength is shown to be 360 nm from the signal-to-background ratio spectrum; emission is measured at 555 nm. The detection limit is 9 ng kg^?1 for a standard uranium sample. Relative standard deviations in the determination of ca. 50 ng kg^?1 uranium in silica samples are about 10%.     

A comparative analysis of uranium in potable waters using laser fluorimetry and ICPMS techniques

The main objective of this work is the accurate measurement of uranium in the potable water sources of Muktsar district of Punjab, India. In the present work, a laser fluorimetry technique was used for the analysis of uranium. Inductively coupled plasma mass spectrometry (ICPMS) technique was also applied to verify and compare the uranium content analyzed using laser technique. About 16 samples from waterworks, bore wells, and hand pumps that supply the drinking water to local population were collected for this purpose. An indigenous laser fluorimeter supplied by RRCAT, Indore was employed for the analysis. Uranium concentrations obtained were in the range from 0 to 10???g?L^?1 in ten samples, 11?C30???g?L^?1 in three samples, and more than 100???g?L^?1 in three samples namely Channu ground water, Warning Khera pump, and Killanwale village hand pump. The USEPA guideline value for uranium in safe drinking water is 30???g?L^?1. Also, a data comparison with similar studies carried out in other countries is presented.     

A resonance light scattering method for the determination of uranium based on a water-soluble salophen and oxalate

A resonance light scattering (RLS) method for the direct detection of uranium (VI) or uranyl in aqueous solution without separation procedure has been reported in this paper. Sulfo-salophen, a water-soluble tetradentate Schiff base ligand of uranyl, reacted with uranyl to form a complex. The complex reacted further with oxalate to form supramolecular dimer with large molecular volume, resulting in a production of strong RLS signal. The amount of uranium (VI) was detected through measuring the RLS intensity. A linear range was found to be 0.2–30.0 ng/mL under optimal conditions with a detection limit of 0.15 ng/mL. The method has been applied to determine uranium (VI) in environmental water samples with the relative standard deviations of less than 5 % and the recoveries of 98.8–105.8 %. The present technique is suitable for the assay of uranium (VI) in environmental water samples collected from different sources.     

Health risks associated with the exposure to uranium and heavy metals through potable groundwater in Uttarakhand state of India

The present work aims to assess health risks associated with the exposure to uranium and heavy metals via potable groundwater in Uttarakhand state of India. For this purpose, potable groundwater samples were collected from the area and analyzed using LED fluorimetry and inductively coupled plasma mass spectrometry (ICPMS). The radiological (carcinogenic) and chemical (non-carcinogenic) risks associated with the exposure to uranium in majority of locations were observed below the safe limits suggested by WHO and USEPA. The levels of heavy metals present in potable groundwater were found well below the permissible limits recommended by WHO. An inter-comparison exercise between the results obtained with LED fluorimetry and ICPMS techniques was performed for the assurance of reliability and accuracy of results. The results were found in good agreement with each other.

     

Determination of uranium isotopes in urine samples from radiation workers using 232U tracer, anion-exchange resin and alpha-spectrometry

Bioassay technique is used for the estimation of actinides present in the body based on the excretion rate of body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha-spectrometry requires pre-concentration of large volumes of urine. This paper deals with standardization of analytical method for the determination of U-isotopes in urine samples using anion-exchange resin and ²³²U tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of uranium along with calcium phosphate. Separation of U was carried out by Amberlite, IRA-400, anion-exchange resin. U-fraction was electrodeposited and activity estimated using tracer recovery by alpha-spectrometer. Eight routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range of 51% to 67% with a mean and standard deviation of 60% and 5.4%, respectively.     

A novel method of synthesizing solid phase adsorbent silica modified with xylenol orange: application for separation, pre-concentration and determination of uranium in calcium rich hydro-geochemical samples and sea water—Part 1

A novel, single-step route has been developed for the synthesis of solid phase adsorbent silica modified with xylenol orange. The addition of cationic surfactant cetyl tri-methylammonium bromide during the synthesis of the adsorbent supports the formation of a stable coating of xylenol orange on silica. The adsorbent showed no signs of degradation in contact with organic solvents and with solutions of varying pH between 1 and 9. This adsorbent has been used for separation and pre-concentration of uranium from hydro-geochemical samples with high calcium content and from sea water. Quantitative sorption of uranium was observed above pH 3 and complete desorption can be achieved using 0.2 M sodium pyrophosphate solution. The uranium content in the extract was determined by laser fluorimetric technique. The equilibration time is 30 min. The sorption capacity of the adsorbent for uranium is 10 mg g^?1. An enrichment factor of 50 was obtained by this procedure taking 500 mL of sample solution. Uranium concentrations down to 0.05 ng mL^?1 can be determined after pre-concentration using this method. The relative standard deviation at an 0.1 ng mL^?1 level is ±15%.     

Relevance of ICRP metabolic model of Th in bio-assay monitoring

This paper compares the urinary excretion levels of Th obtained in bio-assay monitoring using the neutron activation technique with those predicted by applying the ICRP metabolic model to the measured Th activity in chest and total body of a group of Thorium plant workers. The results indicated much lower urinary Th excretion as compared to what was expected on the basis of the ICRP model. Lower urinary excretion in occupational subjects is explained in terms of negligible contribution of skeleton and soft tissue to the activity excreted in urine. It is suggested that the existing model should be modified to enable it to be applicable to the bio-assay monitoring of occupational workers.     

Uranium and thorium exposures associated with conventional mining

Internal contamination with radioactive materials of mining workers is a common problem in Brazil. This is caused by the presence of uranium, thorium, and their natural decay series associated with the mined ore. The clear examples are the workers at the niobium mine located in the state of Goiás. The niobium is associated with considerable quantities of uranium and thorium, but the mine is not legally subject to radiation protection requirements.Twenty mine workers were evaluated using in vitro bioassay techniques (urine and feces). The fecal samples were analyzed by alpha spectrometry using the method developed in the Bioassay Laboratory of the Instituto de Radioproteção e Dosimetria/CNEN which evaluates thorium and uranium isotopes simultaneously. Minor modifications were introduced to measure a higher level of activity, around 1 Bq of uranium per sample. The urine samples were analyzed by alpha spectrometry for thorium and by fluorimetry for uranium. The results obtained show that a control of the occupationally-exposed workers is necessary.     

Application of laser-induced optical fiber fluorimetry to the analysis of ultralow level of uranium

A laser-induced optical fiber fluorimetry has been reported for the analysis of ultralow level of uranium. The fluorescence spectrometer includes five major components: a pulsed nitrogen laser, optical fibers, an optrode, a detector, and a boxcar. The fluorescence intensity of uranyl ions is linear with respect to the concentration of uranium. The detection limit of uranium in 1M phosphoric acid is 24 ppb. This technique can be used for the remote, on-line measurement of low level uranium.     

The use of LA-SF-ICP-MS for nuclear forensics purposes: uranium isotope ratio analysis

This work describes the utilization of the laser ablation sector field inductively coupled plasma mass spectrometry (LA-SF-ICP-MS) technique for the determination of uranium isotopic composition in a highly enriched uranium sample. The measurements were performed on a continuous ablation with low energy density and defocusing, which demonstrated to be the optimum to reach the best signal stability. The measurements were improved by adjusting the following parameters: RF power, laser beam diameter, defocusing of laser beam, laser energy, laser energy density, auxiliary gas and sample gas. The ²³⁵U/²³⁸U isotope ratio with its respective uncertainty was 16.36 ± 0.15 and its precision was 1.12 % relative standard deviation. The uncertainties were estimated following the ISO GUM, with a confidence level of 95.45 % (k = 2.00). When compared the isotope abundances to the Round Robin Exercise Number 3’s average results a difference of 0.46 % has been found and when compared to supplier’s value, the difference was 0.41 %. The results presented by the measurements revealed that the LA-ICP-MS technique offers a rapid and accurate alternative to measure uranium isotope ratios without any sample preparation, since it allows carrying out the measurements straight on the sample. Moreover, it preserves the testimony—very important for safeguards and nuclear forensics purposes.     

Determination of plutonium isotopes in urine samples from radiation workers using <Superscript>236</Superscript>Pu tracer,anion exchange resin and alpha spectrometry

Bioassay technique is used for the estimation of actinides present in the body based on their excretion rate through body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha spectrometry requires pre-concentration of large volumes of urine. This paper deals with standardization of analytical method for the determination of Pu-isotopes in urine samples using anion exchange resin and ²³⁶Pu tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of plutonium along with calcium phosphate. Separation of Pu was carried out by Amberlite, IRA-400, anion exchange resin. Pu-fraction was electrodeposited and activity estimated using tracer recovery by alpha spectrometer. Twenty routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range 74–96% with a mean and standard deviation of 85 and 6% respectively.     

Determination of Ultra Trace Amounts of Uranium (VI) by Adsorptive Stripping Voltammetry Using L-3-(3, 4-dihydroxy phenyl) Alanine as a Selective Complexing Agent

Abstract

The spectrophotometric behavior of uranium (VI) with L-3-(3, 4-dihydroxy phenyl) alanine (LDOPA) reagent revealed that the uranium can form a ML₂ complex with LDOPA in solution. Thus a highly sensitive adsorptive stripping voltammetric protocol for measuring of trace uranium, in which the preconcentration was achieved by adsorption of the uranium-LDOPA complex at hanging mercury drop electrode (HMDE), is described. Optimal conditions were found to be a 0.02 M ammonium buffer (pH 9.5) containing 2.0 × 10^?5 M (LDOPA), an accumulation potential of ? 0.1 V (versus Ag/AgCl) and an accumulation time of 120 sec.

The peak current and concentration of uranium accorded with linear relationship in the range of 0.5–300 ng ml^?1. The relative standard deviation (at 10 ng ml^?1) is 3.6% and the detection limit is 0.27 ng ml^?1. The interference of some common ions was studied. Applicability to different real samples is illustrated. The attractive behavior of this reagent holds great promise for routine environmental and industrial monitoring of uranium.     

Metabolism of levamisole and kinetics of levamisole and aminorex in urine by means of LC-QTOF-HRMS and LC-QqQ-MS

The antihelminthic drug Levamisole can enhance cocaine effects by conversion into the amphetamine-like drug aminorex. We describe an LC-MS method for the determination of levamisole and its metabolite aminorex in human urine. Selectivity is given, calibration curves were linear within the calibration range 2.5–250 ng/mL; limits of the method were LoD 0.51 ng/mL, LoQ 1.02 ng/mL for levamisole and LoD 0.65 ng/mL, LoQ 0.76 ng/mL for aminorex. Precision data was in accordance with the guidelines (intraday precision for aminorex ranged between 5.75 and 11.0 % for levamisole between 8.36 and 10.9 %; interday precision for levamisole 10.9–16.9 % and for aminorex 7.64–12.7 %; accuracy data for levamisole ?1.96 to –14.3 % and for aminorex?11.9 to–18.5 %). The validated method was successfully applied to study the urinary excretion of levamisole after the administration of 100 mg of levamisole orally. Levamisole and aminorex could be detected in post-administration urine samples. Levamisole could be detected up to 39 h after ingestion, while aminorex was detectable up to 54 h. Maximum aminorex concentrations were 45 ng/mL urine. Further metabolites of levamisole after oral ingestion by means of liquid chromatography hybrid quadrupole time-of-flight high-resolution mass spectrometry (LC-QTOF-HRMS) were identified. Only 0.5 % of the ingested drug was quantified as unchanged levamisole in urine. Besides aminorex, five isomers of aminorex and 4 hydroxy-metabolites of aminorex or its isomers were found. Furthermore, levamisole is also hydroxylated and eliminated free or conjugated with sulfate or glucuronide into urine.     

Modified respiratory tract model for uranium: Its implications on bioassay interpretations

The excretion of inhaled poorly transportable compounds of uranium relative to chest content has been measured in humans by a substantial number of measurements of urine, feces, andin vivo measurements over the chest. The use of these measurements have permitted us to compare the results predicted by the models with empirical observations in humans. The ICRP-30 model for inhaled class Y compounds of uranium along with the ICRP-30 systemic model, no matter what the particle size, grossly underpredicts urinary excretion over time than that observed in human occupationally exposed to poorly transportable compounds of uranium by inhalation. Conversely, if urinary excretion were to be used to estimate the contents of poorly transportable uranium compounds in the lung using ICRP-30 models, the results would be significantly overestimated. The new ICRP (ICRP-66) respiratory tract model also grossly underestimates urinary excretion of inhaled poorly transportable uranium compounds and exacerbates the problem, at least for the default values of the parameters of the model. A lung model derived from the original ICRP-30 lung model, which is named modified, has been proposed in this work. It predicts urinary excretion better, even though it is not entirely satisfactory in predicting urine/fecal ratio in excreta.