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  • Author or Editor: S. Kayasth x
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Abstract  

The combination of neutron activation analysis (NAA) and electrochemistry has been used to study the deposition behavior of rare earth elements, as it is reported that excepting La, no other rare earths are electrodeposited. The radiotracers of rare earth elements were electrolyzed in an aqueous medium on a graphite electrode by varying the voltage and time of electrodeposition, thereby optimizing the final experimental conditions for quantitative deposition of rare earth elements. The observations are reported in this work.

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Abstract  

A simple preconcentration approach for quantitative separation and determination of traces of rhenium in geological matrix using neutron activation analysis is presented in this work. Anionic species of rhenium were collected on small amounts of anion-exchange resin beads from a large-size geological sample solution followed by neutron irradiation of the resin beads and measurements of rhenium activity for its quantification. ∼200 mg of resin beads were used to concentrate rhenium from 0.5 to 5 gram of the borehole samples. Radioactive tracers of the analyte directly and in the presence of the matrix were used to establish the separation process. During the present work the detection limit of rhenium was found to be 10 ng/g.

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Abstract  

Appreciable amounts of different arsenic compounds are used in the manufacture of glass and glass ampoules (injection vials and bottles) used to store drugs. Exposure/intake of arsenic to human beings may result in skin ulceration, injury to mucous membranes, perforation of nasal septum, skin cancer and keratoses, especially of the palms and soles and may cause detrimental effects. Considering the toxicity of arsenic, even if traces of arsenic from such glass containers/ampoules are leached out, it can impart damage to human beings. To check the possibility of leaching of arsenic from glass ampoules, a simple methodology has been developed. Different makes and varieties of glass ampoules filled with de-ionized water were subjected to high pressure and temperature leaching for varying amount of time using autoclave to create extreme conditions for the maximum leaching out of the analyte. Subsequently, the determination of the arsenic contents in leached water using neutron activation analysis is reported in this paper in detail with observations.

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Abstract  

Basic aspects of pollution and the role of analytical chemistry in environmental monitoring are highlighted and exemplified, with emphasis on trace elements. Sources and pathways of natural and especially man-made polluting substances as well as physico-chemical characteristics are given. Attention is paid to adequate sampling in various compartments of the environment comprising both lithosphere and biosphere. Trace analysis is dealt with using a variety of analytical techniques, including criteria for choice of suited techniques, as well as aspects of analytical quality assurance and control. Finally, some data on trace elements levels in soil and water samples from India are presented.

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Abstract  

During the present work rare earth elements (REEs) in Periyar River water and in seawater from the region of Mumbai, India, have been measured via neutron activation analysis. To separate and concentrate REEs a pre-irradiation separation approach via ion exchange was adopted. Standard addition and radiotracer studies were carried out to validate the analytical methodology including the recoveries of the separations. The measured REE concentrations in the water samples are presented and discussed.

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Abstract  

A method has been developed for the determination of Re, Se, As, Sb, Pt, Au, Te and Rare Earth elements in samples collected at various stages during the production of copper. Instrumental neutron activation analysis, along with a multielement sequential procedure for radiochemical separation of these analytes has been worked out and the results for various samples are discussed.

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Abstract  

Radiochemical neutron activation analysis /RNAA/ has been applied for the determination of individual rare earth elements /REE/, except Tm, in 8 Indian monazites and one each from Malaysia and Thailand. Because of the very low amounts of heavy rare earths /HREE/ compared to light rare earths /LREE/ in monazite, HREE from Ho onwards have been determined only after the separation of the heavy and light rare earth fractions in the irradiated monazite samples. The results indicate significant variations in REE contents from Eu to Lu among different monazite samples. The chondritic normalized REE patterns of all the samples show a prominent negative Eu anomaly with different slopes at the heavy rare earth end. All the individual REE, except Tm, have been reported for the first time in various Indian monazites.

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Abstract  

Various methods of preparing standards for activation analysis have been reported in the literature. This paper describes the feasibility of preparing ion exchange resin based standards containing predetermined levels of ions. Using a solution of known initial concentration of the ion, and given the value of its distribution coefficient, it is possible to predict the resin concentration that will be obtained. Resins containing ppm levels of copper and manganese have been prepared and their stabilities evaluated over a period of time. The feasibility of preparing a multielement standard has been studied with five rare earth elements (La, Ce, Sm, Eu and Dy).

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Abstract  

A simple separation scheme for the analysis of As, Mn, Mo, Cu and Zn using neutron activation is described. It has been checked using three standard reference materials, A-11 milk powder (IAEA) and bovine liver and orchard leaves (USNBS) and found to give acceptable results. This scheme was applied for determination of these trace elements in mature human milk samples. The concentrations of As, Mn, Mo, Cu in samples obtained from two socio-economic groups—low and middle incomes—were not significantly different. However, Zn levels in samples obtained from the poor income group were significantly lower than in those obtained from the other group.

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Abstract  

Radioactive elements like 232Th and 238U along with their daughter products, form part of all environmental matrices and are getting transferred to living beings by different pathways, leading to a continuous radiation exposure and need to be monitored. This paper presents an analytical methodology, highlighting the need to separate interfering beta- and gamma-emitters from the analytes, when neutron activation analysis is employed for the determination of traces of uranium and thorium in soil and plant materials. The method has been applied to the soil and plant materials from selected regions of India, along with standard reference materials to verify the validity of the proposed separation scheme. The overall reproducibility of the procedure was 2–10%. The concentration values of uranium and thorium so obtained, have been used to calculate transfer factors from soil to various parts of wheat plant.

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