Determination of rare-earth eleemnts in rock samples by neutron activation analysis

A Ge(Li) detector combined with cation exchange separation has been used for the determination of 12 rare-earth elements (La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu) in rock samples by neutron activation analysis. After purification by the conventional hydroxide-fluoride precipitation, the rare-earth elements are separated into two fractions, light (La-Tb) and heavy (Ho-Lu), by EDTA cation exchange, and the γ-activities of the two fractions are measured by a Ge(Li) detector. The heavy rare-earths, such as Ho, Er, and Tm, can be easily γ-counted without serious interference from the intense Compton background and photopeaks due to the light rare-earths such as¹⁴⁰La,¹⁵³Sm,¹⁵²Eu, and¹⁶⁰Tb. The chemical yields (60%) for the individual rare-earths are determined by a reactivation technique. The results obtained for the U.S. Geological Survey standard rocks G-1 and W-1 are compared with the previously reported data.     

Determination of elements in bovine tissues by instrumental neutron activation analysis

Instrumental neutron activation analysis was carried out to obtain the normal concentration of trace elements in bovine tissues (heart, liver, kidney, spleen, lymph nodes) and serum. Concentrations of 17 elements were determined. In this paper, concentrations of Al, Br, Cs, In and Rb are given and correlations of concentrations are discussed between Cl and Br and between K and Cs or Rb. Significant positive correlations have been found between Cl and Br concentrations in all tissues, between K and Cs concentrations in tissues excluding kidney, and between K and Rb concentrations in tissues excluding liver.     

Determination of pollutants in dwellings by neutron activation analysis and X-ray fluorescence

Metallic pollutants were measured in dwellings in Mexico City by instrumental neutron activation analysis (INAA) and X-ray fluorescence techniques. Monitoring was performed in the west side of the city and in the winter season. In general the average concentration of contaminants collected, when compared with the average concentrations reported in a previous paper, have increased with time and in the particular case of lead and mercury some samples are above the indicative WHO maximum levels.     

Determination of Sc in rock samples by substoichiometric thermal neutron activation analysis

A rapid, selective and simple method has been developed for the determination of Sc in rock samples by thermal neutron activation analysis, employing substoichiometric solvent extraction of Sc(III) with alizarin into 1-octanol. Two samples and a standard can be processed and counted within three hours.     

Determination of lanthanum in phosphate rock and in its products by neutron activation analysis

Lanthanum was determined in phosphoric rock and in its products obtained in the process of production of phosphoric acid and fertilizers in Mexican plants. The method used for the determination of lanthanum was neutron activation analysis. It is observed that the concentration of lanthanum is higher in the fraction of calcium salts.     

Determination of iridium and gold in rock samples by using pre-concentration neutron activation analysis

Nickel sulfide (NiS) fire assay was used for the pre-concentration of Ir and Au in rock samples. The beads obtained after fire assay were irradiated directly with neutrons to determine Ir and Au. To suppress the reaction of ⁵⁸Ni(n,p)⁵⁸Co, the fire assay was carried out by using a small amount of Ni (0.0625 g) and the NiS bead samples were irradiated by neutrons with high Cd ratios. Analytical results of Ir and Au for rock samples were close to literature values, confirming that our procedure of INAA with pre-concentration can be applied to rock samples for the determination of ppb to sub-ppb level of Ir and Au.     

Determination of chlorine, bromine and iodine in rock samples by radiochemical neutron activation analysis

Chlorine, bromine and iodine (hereafter, halogens) were detemined for rock samples by radiochemical neutron activation analysis. The powdered samples and reference standards prepared from chemical reagents were simultaneously irradiated for 10 to 30 minutes with or without a cadmium filter in a TRIGA-II reactor at the Institute for Atomic Energy, Rikkyo University. The samples were subjected to radiochemical procedures of halogens immediately after the irradiation. Iodine was firstly precipitated as PdI₂, and chlorine and bromine were successively precipitated as Ag-halides at the same time. In this study, geological standard rocks, sedimentary rocks and meteorites were analyzed for trace halogens. In some Antarctic meteorites, iodine contents were observed to be anomalously high. Chlorine contents also are somewhat high. The overabundance of iodine and chlorine must be caused by terrestrial contamination on the Antarctica.     

Determination of trace siderophile elements in rock and meteorite samples by radiochemical neutron activation analysis

A simple and effective radiochemical procedure for radiochemical neutron activation analysis (RNAA) of ultra-trace siderophile elements (Ru, Re, Os and Ir) and rare earth elements (REEs) in rock and meteorite samples is presented. To design the procedure, several separation schemes of siderophile elements were examined by using radioactive tracers. By applying the procedure to rock and meteorite samples, we have determined Ru, Re, Os, Ir and REEs, and confirmed that our values were in agreement with the literature values. Our detection limits for Ru, Re, Os, La, Sm and Eu are significantly low compared with those for ICP-MS.     

Determination of tungsten in ores by X-ray fluorescence technique and X-rays in neutron activation analysis

Two distinct analytical methods have been described for analysis of W in tungsten ores. For the proposed study, thick and thin samples were analyzed by using X-ray fluorescence technique with great accuracy. Standard comparison method is based on the measurement of K line for tungsten. Also, W has been determined in similar ore samples by neutron activation analysis followed by X-ray spectrometry employing a²³⁸Pu-Be neutron source. The measured Re K-X rays are emitted in internal conversion of¹³⁷W produced during thermal neutron activation.     

Determination of nanogram quantities of gold in biological tissues by nondestructive neutron activation analysis

We describe a method for gold analysis in kidney and liver. The technique is simpler than other methods in that it does not require ashing or acid digestion of the sample. The tissue is dried, placed into a polyethylene vial and diluted with a 2 ml sodium chloride solution. Gold concentration is determined by neutron activation analysis. Samples are irradiated for two hours at a thermal neutron flux of 10¹²n·cm⁻²·s⁻¹ and are then allowed to decay for 3–4 days before counting. The detection limit (20 ng Au/ml) and precision (±6.1%) permits the accurate analysis of gold in these tissues. This technique could aid in a re-examination of gold metabolism.     

Determination of elemental and ionic compositions for diesel exhaust particles by particle induced X-ray emission and ion chromatography analysis.

The purpose of this study is to clarify the chemical characterization of PM2.5 and PM10 in diesel exhaust particles (DEP). Sampling of PM2.5 and PM10 in DEP was carried out in November 1999 using an automobile exhaust testing system at the National Traffic Safety and Environment Laboratory, with a diesel truck (engine type: direct injection, displacement: 7,961 cc, carrying weight: 2,020 kg, equivalent inertia weight: 5,600 kg) placed on a chassis dynamometer. Sampling conditions included idling, constant speed of 40 km/h, M-15 test pattern and 60%-revolution/40%-load of maximum power. Samples were collected on a polycarbonate membrane filter (Nuclepore, pore size: 0.8 microm) using a MiniVol Portable Air Sampler (Airmetrics Co., Inc.). The concentrations of several elemental and ionic species in the PM2.5 and PM10 samples were determined by particle induced X-ray emission (PIXE) and ion chromatography analysis. PIXE analysis of the PM2.5 and PM10 samples revealed 15 elements, of which Na, Mg, Si, S, Cl, Ca, Fe and Zn were found to be the major components. Ionic species were Cl-, NO2-, NO3-, SO4(2-), Na+, NH4+, K+ and Ca2+. Concentrations of elements and ionic species under the sampling condition of 60%-revolution/40%-load were highest in comparison with those of the other sampling conditions. The elemental and ionic species data were compared for PM2.5 and PM10; PM2.5 concentrations were 70% or more of PM10 concentrations for the majority of elements, and concentrations of ionic species in PM2.5 and PM10 were almost identical.     

Determination of trace elements in human brain tissues using neutron activation analysis

Neutron activation analysis was applied to assess trace element concentrations in brain tissues from normal (n = 21) and demented individuals (n = 21) of both genders aged more than 50 years. Concentrations of the elements Br, Fe, K, Na, Rb, Se and Zn were determined. Comparisons were made between the results obtained for the hippocampus and frontal cortex tissues, as well as, those obtained in brains of normal and demented individuals. Certified reference materials, NIST 1566b Oyster Tissue and NIST 1577b Bovine Liver were analyzed for quality of the analytical results.     

Multi-element determination in sandstone rock by instrumental neutron activation analysis

Summary Instrumental neutron activation analysis (INAA) was used for the qualitative and quantitative analysis of sandstone samples of Aswan area, in South Egypt. The samples were properly prepared together with standards and simultaneously irradiated by a neutron flux of 7 ^. 10¹¹ n ^. cm^-2.s^-1. in the TRIGA research reactor facilities in Mainz. The gamma-spectra from a hyperpure germanium HPGe detector were analyzed. The present study provides the basic data of elemental concentrations of a sandstone rock. The following elements have been determined: Na, K, Fe, Sc, Cr, Co, Zr, Ce, La, Nd, Sm, Eu, Yb, Lu, Hf, Ta, Th and U. Energy dispersive X-ray fluorescence (EDXRF) was used for comparison and to detect elements which can be detected only by this method.     

Instrumental neutron activation analysis of Obsidian rock

An instrumental neutron activation analysis technique has been developed for the simultaneous determination of up to 30 elements including major, minor and trace elements in Obsidian Rock (a proposed NBS-SRM-278). INAA method involves both short and long irradiations followed by gamma-ray activity measurement with a Ge(Li) detector. The accuracy of the procedure has been checked by analyzing IAEA Reference Materials.     

Reactor neutron activation analysis followed by characteristic X-ray spectrometry

The possibility of applications of characteristic X-rays from radioactive products of reactor neutron activation was investigated with particular emphasis on (n, ), n, n), (n, 2n), (n, p) and (n, ) products with long half-lives. The sensitivity and detection limits of silver, cerium, gadolinium, selenium, cadmium and europium have been investigated. The elements were studied both in a pure and in a matrix form, in both cases the samples were diluted with graphite (90%) to minimize matrix effects (absorption and enhancement).     

Determination of trace iodine in rock samples by epiterhmal neutron activation analysis involving rapid radiochemical separation

Applying rapid radiochemical separation of iodine coupled with epithermal neutron activation, we reliably determined trace amounts /6–95 ng/ of iodine in rock samples such as sedimentary rocks and chondritic meteorites. Our data on meteorites are in good agreement with literature values, but for sedimentary rocks the present data were systematically lower than the literature values. Based on the data from duplicate analyses of some sedimentary rocks and the results of tracer experiments employed parallel to the rock analyses, we concluded that the analytical results obtained in this work for sedimentary rocks were more reliable than the literature values.     

Determination of gold in platinum by neutron activation analysis

The determination of gold in platinum by neutron activation analysis is described. The possibility of screening out the influence of the nuclear reactions on the final result of the determination was studied. In the case of microamounts of gold in platinum, gold was separated previously by extraction chromatography with dithizone as organic stationary phase. Gold fixed on the column was irradiated and determined gamma-spectrometrically.     

Determination of chromium in blood by neutron activation analysis

A procedure for the determination of chromium in blood has been developed with a sensitivity of 5×10⁻³ μg Cr. Dried blood was irradiated with a neutron flux of 10¹² n·cm⁻²·sec⁻¹ in the VVRS reactor for 4 weeks, then the sample was mineralized and the chromium isolated by extraction as perchromic acid. The determination of the chromium content was accomplished by measuring the 0.32 MeV gamma energy of⁵¹Cr. In order to make correction for the interfering reaction⁵⁴Fe(n,α)⁵¹Cr, the formation of chromium from high-purity iron was investigated. The chromium content of the blood samples was between 1.03×10⁻² and 5.2×10⁻² ppm Cr.