Results 1 - 10 of 19184
Results 1 - 10 of 19184. Search took: 0.04 seconds
|Sort by: date | relevance|
[en] Uranium content of coal samples from seven areas in the Philippines, i.e. Cebu, Semirara, Bislig, Albay, Samar, Malangas and Polilio Is. was found to contain trace quantities of uranium. The mean value of 0.401 ppm U is lower than reported mean uranium contents for coal from other countries. (ELC)
[en] This initial report on the plutonium concentration in lungs of Filipino adults is based on four samples. The data obtained suggest that the average of concentration in lungs of Filipinos is similar to that observed in other countries. This could be attributed to fallout resulting from nuclear test explosions conducted by neighboring countries. The result of this study will be useful in initiating the establishment of plutonium burden of Filipinos. (ELC). 2 tabs
[en] To screen the plants in Elsaraf dam (Gedaref-Sudan ), for their ability to uptake metal ions and the effect of seasonal rain on the availability of these metal ions for plants , trace elements in plant roots and the associated soil were studied in two seasons using atomic absorption spectroscopy and X-ray fluorescence. The nutrient elements, (Fe, Mn, Zn, Cu, Co) showed higher concentrations than toxic elements (Cr, Ni, Cd) in both plant and soil samples.Iron has the highest concentration 5490/5660 and 3358/3680 mg/100g, manganese has shown the second highest concentration followed by nickel and zinc. Copper, cobalt and chromium have shown relatively similar concentrations, while cadmium has shown the lowest concentration. In general, almost for all elements the soils have shown higher concentration followed by the plant. Estimation of soil/plant transfer factor (CR) that Cyperus rotandus has the highest affinity towards accumulating most of the metal ions, while the rest of plants have shown almost similar affinity.
[en] The laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) system (Nd-YAG laser: 266nm, 20Hz, 5ns) is used to determine the concentration of trace element in three different Egyptian geological raw gem stones (Tourmaline, Zircon and Beryl). The powdered geological samples are melted together with a lithium borate mixture (90% Li2B4O7, 10% LiBO2) in a muffle furnace at 1050C degree to homogenize the chemical distribution. In order to determine the relative sensitivity coefficients of the elements, different geological standard reference materials (SRM) (NIM-G, NIM-L, NIM-N and NIM-S) (coming from National Institute of Metallurgy (NIM), South Africa) are prepared by the same procedure. Furthermore calibration curves have been measured on the geological SRMs. The developed analytical methods for trace element analysis of investigated geological samples by LA-ICP-MS is discussed. The analytical results are verified by additional ICP-MS measurements on digested samples.
[en] A novel methodology for extraction and preconcentration of trace metals based on cloud point phenomenon was optimized and applied to the analysis of Co(II) and Cu(II) in a certified reference material (CRM), using Triton X-100 as nonionic surfactant, and AAS for the determination. Different parameters that can influence the extraction efficiency were studied, such as pH and ionic strength of the solution. The precision, accuracy and detection limits of the method were determined using a CRM from the Environmental Analysis Laboratory. The analysis showed the linearity of the method, for the concentration levels of Cu(II) and Co(II), with high precision and low variability indices . The recoveries were around 94% for both metals. The data obtained presented in this work is part of the validation file of the proposed analytical procedure for the determination of heavy metals. (Author)
[en] A sensitive linear-sweep polarographic method for the determination of thorium is described. It is based on the thorium complex with Xylidyl Blue I (XBI) in a medium containing ethylenediamine, 1, 10-phenanthroline, oxalic acid and ninhydrin, at pH 10.5-11.5. The complex has been proved to be Th(XBI)2, with log β'=9.6. The method can be used to determine trace amounts of thorium over the range 3.5x10-8-3x10-6M. The detection limit is 1x10-8M. A solvent extraction procedure is necessary to eliminate interference from several cations. The method has been applied to determination of traces of thorium in minerals, with good results. (author)
[en] The authors performed radiochemical separation either from metals (metals as targets or analyzed matrices) or using metals (metal collectors). Therefore, the theoretical part of this paper will be devoted to the study of chemical interactions of metals in open-quotes melted metal-trace elementclose quotes systems at high temperatures; the melted metal was either a collector or a matrix element. These studies, important for the practical use of radiochemical analysis, were conducted using tracer technique and autoradiography. The experiments were performed with master alloys labeled with radionuclides. The authors adopted the technique described earlier. The labeled master alloys were also directly used in the development of procedures for separating and concentrating radionuclides
[en] The introduction briefly discusses some theoretical and practical problems of the spectrophotometric determination of trace elements. Among other subjects, the possibilities of spectrophotometric methods in determination of traces, the sensitivity of methods and its increase, preconcentration of trace elements, blank, the purity of reagents and vessels, precision and accuracy are referred. The second section discusses absorbing systems as a base of the sensitive spectrophotometric methods: complexes with organic and inorganic reagents, ternary complexes, amplification reactions, various organic reactions, and the role of the extraction. The third section contains the critical selection of the sensitive methods for individual elements. The following sections are devoted to the determination of the trace elements in samples of various types, such as biological materials, foods, waters and effluents, air, minerals, semiconductor materials, high purity chemicals, and metals. 738 references, 18 tables