Madan Lal

Elemental analysis of selected Indian monazite ores by energy dispersive X-ray fluorescence/EDXRF/spectroscopy

Analysis by Energy Dispersive X-ray Fluorescence spectroscopy of monazite ores from Kerala /Chavara and Manavalakurichi/, Orissa /Chattrapur/ and Tamil Nadu /Tirunelveli/ has been carried out for the determination of their elemental composition using109Cd /annular/ and241Am /disc/ radioisotope sources. The elements Y, Zr, Mo, Pb, Th and U were analyzed using a109Cd source, and the elements La, Ce, Pr, Nd, Sm, Gd and Dy were analyzed using the241Am source in side source geometry. Quntitative results on these 13 elements present in these ores were obtained by the EDXRF technique. It was seen that despite the diverse geological settings, there is remarkable similarity in the elemental composition of these ores, although some trace elements do show certain variations from sample to sample. These results are presented and discussed in this paper.

Trace element profiles in oesophageal neoplasms determined by proton-induced X-ray emission.

Trace element concentrations were determined in surgically resected, cancerous human oesophageal tissue by proton-induced X-ray emission (PIXE) analysis. Each sample was divided into six zones, E3 and E4 formed the central tumour region, E1 and E2 were proximal to the oesophagus and E5 and E6 distal to the oesophagus. Malignancy was confirmed histopathologically in all cases. Samples were dissolved in NaOH solution and pipetted onto a thin mylar film for analysis by a proton beam from a Van de Graaff accelerator. Titanium, Fe, Cu, Zn, As, Rb, Br and Pb were detected in varying concentrations. Of these, Ti, Fe, Cu, Zn and As showed specific behaviour in the six zones.

Characterization of gem stones (rubies and sapphires) by energy-dispersive x-ray fluorescence spectrometry

Trace elemental analyses of rubies and sapphires from different countries of origin were carried out by the EDXRF technique. It was found that K, Ti, Cr, Fe, Cu, Zn, Sr and Ba are generally present in natural rubies and Cr, Ni, Cu and Zr in synthetic ruby. The synthetic ruby shows a clean spectrum devoid of iron whereas the presence of Fe is seen in all the naturally occurring rubies irrespective of the country of origin. The elements present in Indian sapphires are Ca, Fe, Sr and Mo and their estimated concentrations are 0.10, 0.18, 0.029 and 0.006%, respectively. Further, preliminary XRD studies showed patterns of synthetic rubies different from those of the naturally occurring rubies. The results demonstrate that EDXRF can be used to distinguish between natural and synthetic rubies. Copyright

Studies of blood lead levels in children by proton-induced X-ray emission (PIXE)

Blood lead levels of children admitted to Sion Hospital, Bombay (India), from the adjoining Dharavi slum areas have been determined by proton-induced X-ray emission (PIXE). Blood samples were collected from 36 children with suspected lead poisoning and from 20 control children. The analysis showed that the lead concentration of the patients varied from 0.1 to 6.0 micrograms ml-1. In addition to lead, K, Ca, Fe, Cu, Zn, Se, Br and Rb were also detected simultaneously, of which the concentrations of Fe, Cu, Zn, Se, Rb and Pb were determined. The high blood lead levels of the children from this area may be ascribed to environmental pollution due to heavy vehicular traffic and industrial sources.

STUDY OF TRACE ELEMENT ABNORMALITIES IN BLOOD OF CHRONIC RENAL FAILURE (CRF) PATIENTS BY PROTON-INDUCED X-RAY EMISSION (PIXE)

A study of trace element abnormalities in serum of uremic patients has been carried out by Proton-induced X-ray emission (PIXE) in the case of non-dialysed, hemodialysed and post-transplantation. Forty two patients and eight healthy controls selected for this study were grouped on the basis of their Serum Creatinine (SC) levels. Serum samples of these subjects were converted into solution by acid digestion and the solutions were micropippetted and dried on a thin mylar sheet to be mounted on a sample holder of the PIXE chamber. Proton beam from Van de Graaff accelerator (Trombay, India) of 2.5 Mev energy was employed for exciting the characteristic X-rays of the elements present in the samples and their X-rays were detected by a Si(Li) detector. The results obtained showed significant abnormalities in the concentration levels of Ni, Cu, Br, SrandPb amongst various groups. Ni was found to be significantly higher in all the groups compared to controls. Concentration of Cu was also found to be high in the sera of patients on hemodialysis as compared to controls and non-dialysed uremics. Cu levels returned to normal after transplantation. Br was lower in patients undergoing hemodialysis which returned to normal after transplantation. Sr was found to be higher in all groups of renal failure as compared to controls. Patients on hemodialysis accumulated significant quantities of Pb which was found to decrease after transplantation. No significant abnormalities were observed in the case of the elements Zn, Se and Rb.

Determination of tungsten in ores by energy dispersive X-ray fluorescence analysis

The possible determination of tungsten in low grade ores from Northern India, Rajasthan State has been explored by energy dispersive X-ray fluorescence analysis /EDXRF/ technique using radioisotope based excitation of W L X-rays and high resolution Si/Li/ detector system. Finely powdered ore has been diluted with optimal quantity of cellulose and converted into pellets to make it suitable for X-ray analysis after homogenization. The experiments have shown the minimum detectable limit of 33 ppm in diluted matrix. The results are compared with the spectrophotometric stannous chloride-thiocyanate method. EDXRF appears to be encouraging for routine and precise analysis of tungsten in low grade ores.

Trace Elemental Analysis of Extracted Dust from Lungs and Lymph Nodes of Domestic Animals Using X-ray Fluorescence Technique

Samples of dust extracted from the lungs and lymph nodes of certain domestic animals from West Bengal, Orissa, Bihar provinces of India were quantitatively analysed using photon excited energy dispersive X-ray fluorescence technique. Thin specimens were prepared for analysis to minimize matrix enhancement and absorption effects. Amongst the various elements analysed, Hg, Fe, Cu, Zn and Pb were found to be present in appreciable amounts. An important finding was the presence of a very high concentration of Hg in extracted dust samples from West Bengal. The significance of the various results obtained in this investigation is discussed.

Elemental analysis by radioisotope-excited XRF during thermit smelting of ferrovanadium and niobium

The energy-dispersive x-ray fluorescence (EDXRF) technique was applied to the determination of major and trace elements present in aluminothermically smelted ferrovanadium and niobium. Rapid and multielemental analysis of thermit feed and product aided in the appropriate alterations of the charge constituents to obtain the optimum charge composition. The results of analysis by the EDXRF method were verified using wet chemical analysis for a few typical samples of the product and were found to be in close agreement.

Application of the radioisotope excited X-ray fluorescence technique in charge optimization during thermite smelting of Fe-Ni, Fe-Cr, and Fe-Ti alloys

A wide range of ferroalloys are used to facilitate the addition of different alloying elements to molten steel. High-carbon ferroalloys are produced on a tonnage basis by carbothermic smelting in an electric furnace, and an aluminothermic route is generally adopted for small scale production of low-carbon varieties. The physicochemical principles of carbothermy and aluminothermy have been well documented in the literature. However, limited technical data are reported on the production of individual ferroalloys of low-carbon varieties from their selected resources. The authors demonstrate her the application of an energy dispersive X-ray fluorescence (EDXRF) technique in meeting the analytical requirements of a thermite smelting campaign, carried out with the aim of preparing low-carbon-low-nitrogen Fe-Ni, Fe-Cr, and Fe-Ti alloys from indigenously available nickel bearing spent catalyst, mineral chromite, and ilmenite/rutile, respectively. They have chosen the EDXRF technique to meet the analytical requirements because of its capability to analyze samples of ore, minerals, a metal, and alloys in different forms, such as powder, sponge, as-smelted, or as-cast, to obtain rapid multielement analyses with ease. Rapid analyses of thermite feed and product by this technique have aided in the appropriate alterations of the charge constitutents to obtain optimum charge consumption.

Detection limits of high temperature superconducting materials on various substrates by energy dispersive X-ray fluorescence and proton induced X-ray emission methods

Application of energy dispersive X-ray fluorescence (EDXRF) and proton induced X-ray emission (PIXE) methods has been demonstrated for determining the elemental composition of thin film superconducting materials. The results of analysis carried out by EDXRF method have been compared with those obtained by PIXE method. Thin films of YBa2Cu3O7 superconducting material were deposited on various substrates such as thin mylar sheet and thick substrates of SrTiO3, MgO and Al2O3. In thin backing the minimum detection limits obtained for Cu, Y, Ba by the PIXE method are 20 ng, 70 ng and 800 ng respectively and the corresponding values by the EDXRF method are 3000 ng, 600 ng and 1000 ng. Detection limits for samples on thick backings deteriorated to a large extent by both methods.