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- Author or Editor: A. Garg x
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Abstract
A radiochemical solvent extraction method has been developed for the determination of Cr(III) using51Cr tracer. It is based on the complexation of Cr(III) with 8-hydroxyquinoline (oxine) and acetylacetone as mixed ligands at pH 3.8 and extraction in chloroform. Effect of various parameters such as pH, time of equilibration, nature of solvent, quantitative nature, effect of diverse ions has been studied. The method can be used up to 200 ng of Cr.
Abstract
Instrumental neutron activation analysis (INAA) has been used for the determination of 27 elements (Ag, Au, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Ga, Hg, Hf, K, La, Mn, Na, Sb, Sc, Se Sr, Th, P, Ta, Tb, Zn and Zr) in 15 water samples collected from different sources (reservoirs, well, borewell, sewage tank, river, rain) in and around Nagpur city (central India) including doubly distilled and a sea water sample from Bombay. Sample residues after evaporation were irradiated at a thermal neutron flux of 1012–1013 n·cm–2·s–1 for 10 min, 1d and 1wk and counted using a HPGe detector and an 4k MCA at different intervals. Several environmental standards from NIST (USA), NIES (Japan) and USGS rock were also analysed for quality assurance. Wide variations in elemental concentrations have been observed in water samples from different sources. Most elemental concentrations in drinking water from various sources, are within ISI/WHO limits. Sea water showed very high concentrations of Ba, Cr, Co, Fe, Hg, Sb, Se and Zn. For doubly distilled and rain waters, however, very low elemental concentrations of Ba, Ce, Fe, Sc, Hg, Se, Sr and Th were observed.
Abstract
A radiochemical solvent extraction method has been developed for the micro determination of Mo/VI/ using99Mo tracer. It involves removal of99mTc by ethyl methyl ketone /EMK/ and extraction of Mo with tri-n-butyl phosphate /TBP/ from 5M HCl. Different parameters affecting the extraction such as pH dependence, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 2 
g of Mo.
Abstract
Short-term reactor irradiation followed by successive counting over long periods has been used for the nondestructive determination of more the 20 elements in geological and biological samples. The samples, along with USGS standards and NBS SRMs, were irradiated for 5 m, 10 m, 15 m, 1 h, 2.5 h, and 10 h, followed by counting on a Ge/Li/ gamma-ray spectrometer. The technique has been employed for the determination of several major, minor, and trace constituents in geological, biological and environmental samples.
Abstract
Fast neutron-activation methods have been developed for the determination of iron and silicon in USGS and Indian standards and bauxites. Nuclear reactions56Fe/n, p/56Mn and28Si/n, p/28Al were carried out using241Am-Be neutron source and cutting off thermal neutrons with a Cd shield. For Si a cyclic method was adopted due to short half life of28Al /2.3 min/. The methods are non destructive, fast, economic and ideal for bulk analysis of rocks and process control.
Abstract
A precise, sensitive and rapid analytical technique has been developed for the simultaneous determination of Zr and Hf in natural silicate matrices. The technique is based on radiochemical neutron activation analysis and employs a rapid fusion dissolution of the sample and simultaneous precipitation of the Zr−Hf pair with p-hydroxybenzene arsonic acid in an acidic medium. The indicator radionuclides,95Zr and181Hf, are counted with a pair of high resolution Ge(Li) detectors and the95Zr activity is corrected for the contribution from U fission. The chemical yields of the radiochemical separation are based on Hf carrier, which quantitatively carries both Zr and Hf. The yield is determined by reactivation of the processed samples and standards with a252Cf isotopic neutron source and by counting the 18.6 sec half-life179mHf. The sensitivity, precision and accuracy of the procedure are demonstrated by replicate analyses of several standard rocks, meteorites and lunar samples which exhibit a wide range of Zr and Hf abundances.
Abstract
Transition metal dithiocarbamate complexes, [M(S2CN(C2H5)(CH2CH2OH)] (M=Co, Ni, Cu, Zn and Cd) have been prepared and characterized by elemental analysis and infrared spectra. Thermal decomposition of all the complexes occurs in two or three stages. The first stage in all the complexes is always fast with 65-70% mass loss. In all cases the end product is metal oxide except in the case of cobalt complex which gives Co metal as an end product. During decomposition of copper complex, first CuS is formed at ~300C which is converted into CuSO4 and finally CuO is formed. However, decomposition in helium atmosphere yields CuS. SEM studies of transition metal dithiocarbamates reveal needle shape crystalline phase at room temperature and formation of metal sulphide/oxide at higher temperatures. The activation energy varies in a large range of 33.8-188.3 kJ mol-1, being minimum for the Cu complex and maximum for the Zn complex possibly due to d 10 configuration. In the case of Ni, Zn and Cd complexes the order of reaction is two suggesting bimolecular process involving intermolecular rearrangement. However, in other cases it is a unimolecular process. Large negative values of ΔS # for all the complexes suggest that the decomposition process involves rearrangement.
Abstract
Instrumental Neutron Activation Analysis (INAA) has been employed for the multielemental determination of an IAEA intercomparison standard Hay Powder, V-10 and some edible plant leaves consumed in India. The samples were irradiated with thermal neutrons at a flux 
1012 n·cm–2·s–1 in a reactor for 5 minutes, 1, 2, 5, 10 and 15 hours and counted by high resolution 
-ray spectrometry. Nearly 18 elements have been determined. Good agreement is observed for most of the elements in several NBS standards and the proposed CRM V-10. Some edible vegetable plant leaves have also been analyzed.
Abstract
The process of urbanization and industrialization during las two decades has resulted in increased level of air pollution causing hazards to human health. Instrumental neutron activation analysis (INAA) using short and long term irradiation has been employed for the determination of more than 30 elements in suspended particulate matter (SPM) from six metropolitan cities and three industrial surroundings. A comparison of mean elemental contents in dust particulates from commercial, industrial and residential zones of Delhi, Calcutta, Madras, Cochin, Bombay and Nagpur cities has shown wide variation in toxic pollutant (As, Br, Cr, Cu, Hg and Sb) concentrations. Coastal areas have shown higher concentrations of Na, K, Cl and Br. Highly industrialized Bombay showed highest levels of Br, Cl, Cr, Fe, Mg, P, Rb and Sc. Mean elemental contents in fugitive and ambient dust of a cement factory and thermal power station (both in central India) are widely different. SPM levels in fugitive dust of the two industrial surroundings are higher by an order of magnitude compared to ambient air. Analysis of ambient air dust from a paper mill showed highest concentrations of Hg, Sb and Zn. Elemental data have been compared with those of Urban Particulate Matter (SRM 1648), Coal Fly Ash (SRM 1633a) and Vehicle Exhaust Particulate (NIES No. 8) which were analysed for quality control. An attempt has been made to attribute the elemental contents to possible sources of origin.
Abstract
Four plant parts (leaves, roots, fruits and seeds) of twenty samples of sixteen antidiabetic herbs including three commercially marketed capsules have been analyzed for 6 minor (Na, K, Ca, Cl, Mg, and P) and 21 trace (As, Ba, Br, Ce, Co, Cr, Cs, Cu, Eu, Fe, Hg, La, Mn, Rb, Sb, Sc, Se, Sm, Th, V and Zn) elements by instrumental neutron activation analysis (INAA). Further, Ni, Cd and Pb contents were determined by AAS. Elemental data were validated by simultaneously analyzing reference material (RM), MPH-2 Mixed Polish Herbs. Several elements such as Cr and V (1–2 μg/g), Rb (10–40 μg/g), Cs (80–300 ng/g), Se (∼100 ng/g) and Zn (25–60 μg/g) play an important role in diabetes mellitus. Interelemental linear correlations have been observed for Cu vs. Zn (r = 0.89) and Rb vs. Cs (r = 0.87). K/P ratio varies in a narrow range with a mean value of 6.2 ± 1.4. Toxic elements As and Hg were found in <1 μg/g whereas Cd and Pb were in ∼5 μg/g and <10 μg/g, respectively.
