Determination of trace uranium in thorium matrix by laser induced fluorimetry after separation of thorium by its fluoride precipitation using NH4HF2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Susanta Kumar Pradhan ◽  
Balram Ambade
Keyword(s):  
Solvent Extraction ◽  
Certified Reference Materials ◽  
Chelating Agent ◽  
Cost Effective ◽  
Mineral Acid ◽  
Single Step ◽  
Sample Digestion ◽  
Extraction Separation ◽  
Thorium Fluoride

Abstract Thorium, a major element in thorium matrix, quenches uranium fluorescence when it is present above the ratio (Th/U) of 2000 in conventional pellet fluorimetry determination of uranium. A single step ‘sample digestion cum thorium fluoride precipitation’ with NH4HF2 has been developed for separation of bulk thorium as hydrated thorium fluoride precipitates. Uranium in aqueous solution is extracted into ethyl acetate and stripped into pyrophosphate medium (pH ∼ 7), prior to its laser induced fluorimetry determination. Optimizations of certain parameters such as the effects of fluoride flux, mineral acid, temperature and time, stripping solution, diverse ions etc. are discussed in detail. The method has been validated by analyzing a set of synthetic mixtures and certified reference materials of rock samples such as SY-2, SY-3, GSP-2, NKT-1 and CG-2 doped with a large excess of thorium. This method has been applied for the determination of microgram to nanogram uranium in thorium rich rocks and synthetic nuclear grade ThO2 with high degree of accuracy and precision. This is the improvement of the existing method which involves two liquid-liquid solvent extraction separation of thorium and uranium using the chelating agent 2,3-dihydroxynaphthalene at the different pH, compared to one solvent extraction separation of uranium in the present method, because separation of thorium by precipitation as its fluoride has already been carried out during sample digestion step itself. The proposed method involving ammonium hydrogen fluoride in combination with laser induced fluorimetry is simple, rapid, cost effective and more eco-friendly.

scholarly journals Cost-effective Method of Analysis for the Determination of Cadmium, Copper, Nickel and Zinc in Cocoa Beans and Chocolates

2014 ◽  
Vol 4 (1) ◽  
pp. 193 ◽  
Author(s):  
Gideon Ramtahal ◽  
Ivan Chang Yen ◽  
Isaac Bekele ◽  
Frances Bekele ◽  
Lawrence Wilson ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Reference Materials ◽  
Certified Reference Materials ◽  
Control Sample ◽  
Cost Effective ◽  
Cocoa Beans ◽  
Copper Nickel ◽  
Flame Atomic Absorption

<p>The determination of heavy metals in cocoa beans and chocolates is of great importance, due to increasingly stringent regulations being implemented by international legislative bodies and chocolate manufacturers, to protect the health of their consumers. While various techniques exist for heavy metal analyses in cocoa, this study developed a cost-effective, accurate and precise method capable of processing up to 120 samples per batch for the determination of cadmium, copper, nickel and zinc. For sample extractions, a normal laboratory hot plate and locally fabricated high-capacity digestion blocks were used, instead of dedicated block digestion or microwave digestion systems. In addition, only concentrated nitric acid was used, instead of mixed reagents used in standardized methods, for metal extractions from samples, with a sample: extractant ratio of 0.5 g : 10 mL, digestion at 130 ºC, followed by filtration and analysis by flame atomic absorption spectrophotometry. The method was validated with Certified Reference Materials, with heavy metal recoveries generally &gt;95%. Additionally, an in-house quality control sample of ground cocoa nib analyzed together with the Certified Reference Materials was used to monitor the consistency of analyses of heavy metals in cocoa bean samples.</p>

Determination of uranium and thorium in complex matrices by two solvent extraction separation techniques and photon electron rejecting alpha liquid spectrometry

2001 ◽  
Vol 89 (11-12) ◽  
Author(s):  
Marin Ayranov ◽  
K. Wacker ◽  
Urs Krähenbühl
Keyword(s):  
Solvent Extraction ◽  
Marine Sediments ◽  
Alpha Spectrometry ◽  
Complex Matrices ◽  
Separation Techniques ◽  
Extraction Separation ◽  
The Matrix ◽  
Matrix Components

The separation of uranium and thorium from complex matrixes such as marine sediments using solvent extraction and determination by means of Photon-Electron Rejecting Liquid Alpha Spectrometry (PERALS®) has successfully been performed. Two extraction schemes, using TOPO and HDEHP, respectively, were compared for the separation of uranium and thorium from the matrix components. The results show recoveries between 73 and 92% for

scholarly journals Determination of Cadmium, Aluminium, and Copper in Beer and Products Used in Its Manufacture by Electrothermal Atomic Absorption Spectrometry

2002 ◽  
Vol 85 (3) ◽  
pp. 736-743 ◽  
Author(s):  
Pilar Viñas ◽  
Nerea Aguinaga ◽  
Ignacio López-García ◽  
Manuel Hernández-Córdoba
Keyword(s):  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
Certified Reference Materials ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Absorption Spectrometry ◽  
Dihydrogen Phosphate ◽  
Ammonium Dihydrogen Phosphate ◽  
Sample Digestion ◽  
Low Concentrations

Abstract Procedures were developed for determining cadmium, aluminium, and copper in beer and the products used in its manufacture by electrothermal atomic absorption spectrometry. Beer samples were injected into the furnace and solid samples were introduced as suspensions after preparation in a medium containing hydrogen peroxide, nitric acid, and ammonium dihydrogen phosphate for cadmium atomization. Calibration was performed with aqueous standards, and characteristic masses and detection limits were, respectively, 1 and 0.3 pg for cadmium, 18 and 5.4 pg for aluminium, and 5.6 and 6.8 pg for copper. Different samples of beer, wort, brewer's yeast, malt, raw grain, and hops were analyzed by the proposed procedures. Cadmium was found in low concentrations (0.001–0.08 μg/g and 0–1.3 μg/mL); copper (3–13 μg/g and 25–137 μg/mL) and aluminium (0.6–9 μg/g and 0.1–2 μg/mL) were found at higher levels. The reliability of the procedure was confirmed by comparing the results obtained with others based on microwave oven sample digestion, and by analyzing several certified reference materials.

scholarly journals A general strategy for the voltammetric trace determination of tellurium in geochemical and environmental matrices after arsenic coprecipitation and critical assessment of digestion schemes

2020 ◽  
Vol 17 (2) ◽  
pp. 85 ◽  
Author(s):  
Marc Biver ◽  
Montserrat Filella
Keyword(s):  
Reference Materials ◽  
Limit Of Detection ◽  
Chemical Elements ◽  
Certified Reference Materials ◽  
Anodic Stripping Voltammetry ◽  
General Strategy ◽  
Environmental Matrices ◽  
Hypophosphorous Acid ◽  
Sample Digestion

Environmental contextAmong chemical elements classified as elements of strategic importance, tellurium is rapidly becoming an emergent contaminant. There is, however, no accurate and sensitive method for measuring tellurium concentrations in environmental and geological samples (e.g., soils, sediments), and thus it is not possible to determine whether an ecosystem is being polluted by human activities. This study provides a reliable answer to this problem. AbstractA general method is proposed for the determination of tellurium in environmental and geochemical samples. Samples may be digested by any technique (acid or fusion digestion). The tellurium in the resulting solution is reductively coprecipitated with added arsenite by hypophosphorous acid, and the precipitate is redissolved and analysed by catalytic anodic stripping voltammetry. Several sample digestion techniques (acid and fusion digestions) are critically assessed. The method is applied to ore certified reference materials, with tellurium concentrations spanning three orders of magnitude, and sediment certified reference materials (ocean, lake and estuarine). An overall limit of detection (LOD) of 5 ppb is achieved. Acid digestion by H2SO4 and by HClO4 or sintering with Na2O2 in glassy carbon crucibles are shown to be the most adequate sample digestion techniques.

scholarly journals Trace Analysis in End-Exhaled Air Using Direct Solvent Extraction in Gas Sampling Tubes: Tetrachloroethene in Workers as an Example

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Chris-Elmo Ziener ◽  
Pia-Paulin Braunsdorf
Keyword(s):  
Solvent Extraction ◽  
Cost Effective ◽  
Gas Analysis ◽  
Gas Sampling ◽  
Exhaled Air ◽  
Occupationally Exposed ◽  
Analytical Reliability ◽  
Exposure Levels ◽  
Gaseous Analytes

Simple and cost-effective analytical methods are required to overcome the barriers preventing the use of exhaled air in routine occupational biological monitoring. Against this background, a new method is proposed that simplifies the automation and calibration of the analytical measurements. End-exhaled air is sampled using valveless gas sampling tubes made of glass. Gaseous analytes are transferred to a liquid phase using a microscale solvent extraction performed directly inside the gas sampling tubes. The liquid extracts are analysed using a gas chromatograph equipped, as usual, with a liquid autosampler, and liquid standards are used for calibration. For demonstration purposes, the method’s concept was applied to the determination of tetrachloroethene in end-exhaled air, which is a biomarker for occupational tetrachloroethene exposure. The method’s performance was investigated in the concentration range 2 to 20 μg tetrachloroethene/L, which corresponds to today’s exposure levels. The calibration curve was linear, and the intra-assay repeatability and recovery rate were sufficient. Analysis of real samples from dry-cleaning workers occupationally exposed to tetrachloroethene and from nonexposed subjects demonstrated the method’s utility. In the case of tetrachloroethene, the method can be deployed quickly, requires no previous experiences in gas analysis, provides sufficient analytical reliability, and addresses typical end-exhaled air concentrations from exposed workers.

Sign in / Sign up

Export Citation Format

Share Document