Determination of trace and toxic elements in Korean rice CRM by INAA, ICP and AAS

Trace and toxic elements in Certified Reference Material (CRM) made of Korean rice at the Korea Research Institute of Standards and Science have been analyzed by Instrumental Neutron Activation Analysis (INAA). Data intercomparison from the measurement with those of Atomic Absorption Spectrometry (AAS) and Induced Coupled Plasma Spectrometry (ICPS) has been studied. The powdered samples were sterilized at 1.5·10⁶ rad in the bottles using a⁶⁰Co source after sieving and spiking to specific elements such as As, Cd, Cr, Cu and Hg and then the homogeneity of samples was assessed. Rice flour (SRM 1568a) and standard solutions made by the National Institute of Standards Technology (NIST) were used to construct the calibration curves for the INAA and the chemical methods, respectively. The uncertainties and concentration of constituent elements were determined and the possibility of their use for analytical quality control was considered.     

Determination of essential and toxic elements in Libyan foodstuff using instrumental neutron activation analysis (INAA)

Since there is no database in Libya defining the intake of the individuals from different essential (minor and trace) and toxic elements provided through food, drinking water and aerosol, a project has been proposed with the cooperation of IAEA to determine the concentration of a number of elements such as Cs, Fe, Cr, Rb, Sc, Se, Co, Zn in the three mentioned sources. Emphasis was placed on the use of nuclear and nuclear-related techniques. In this paper, the primary results are presented for the concentration of minor and trace elements in some vegetables, spices and other foods which are widely used in the Libyan meals. Instrumental neutron activation analysis utilizing a 10 MW water pool reactor and a γ-ray spectroscopy facility was employed. For quality control, certified reference materials were analyzed simultaneosly with the samples which show good agreements compared with the certified data. Emphasis was given to both elements iron and zinc for their importance.     

INAA multielemental analysis of Nigerian bituminous coal and coal ash

Instrumental neutron activation analysis (INAA) was used to analyzed Nigerian bituminous coal and ash. Good statistical agreement (p0.05) between the literature and reported elemental values of USGS AGV-1 sample was found. Many elements were determined in the coal with some enrichment in the coal ash. Arsenic was measured only in the ash while Hg was present only in the coal. Coal ashing at 800°C contributed to a loss of Hg in the ash. Al, Na, Mg, Ti, Fe, which are major elements were found in the coal as expected, with slight enrichment in the ash. Ca and Si were only obtained in the ash. High ash Al (14.9±0.19%) and Si (25.3±4.11%) levels are of concem due to possible cases of pneumononiosis from inhalation of the particulates. Graphical illustration of the lanthanide concentrations peaked at Ce with a decrease from Sm to Lu. U and Th were also present in the samples showing slight enhancement in the ash. Comparatively low coal elemental values, notably S(1.8%), highly advocate this coal as a good quality fuel-coal.     

Analysis of selected fertilizers imported to Libya for major, minor, trace and toxic elements using ICP-OES and INAA

The concentration of 35 elements (Al, As, B, Ba, Be, Ca, Cd, Co, Cl, Cr, Cu, Fe, K, Mg, Mn, Mo, N, Na, Ni, P, Pb, Rb, S, Sb, Sc, Si, Sr, Tb, Th, Ti, U, V, Yb, Zn and Zr) in six different imported, NPK, NP and K fertilizers were determined by ICP-OES in two different laboratories and by INAA. The fertilizers were labeled as 24/12 (Belgium), 46/18 (Morocco), 50% ammonium sulfate 50% K₂O (Belgium), New 24/12 (Belgium), 16.8.24 (France) and 17.17.17 (France). It is clear that these fertilizers vary widely in their heavy metals and uranium content, and the accumulation of certain elements in vitally important media such as water, soil and food is undesirable from the medical point of view. The results obtained were acceptable and intercomparison between various methods was carried out.     

Trace elements in natural drugs determined by INAA

Natural drugs are widely used for diuretic, phlegm elimination and stomach invigoration purposes. Seventy-five of the most common remedies used by Chinese people have been subjected to trace element survey analysis by instrumental neutron activition. Within this large number of different natural products, fourteen trace elements (K, Sc, Cr, Fe, Co, Zn, Br, Rb, Cs, La, Sm, Eu, Au and Th) are commonly detected. Among these elements, Fe had the highes: concentration followed by Zn, and Rb, Sm, Eu and Au were found to have the lowest concentations. Although the three groups of natural drugs exhibit a widely different therapeutic action, the concentration ranges of the fourteen elements were very similar. While this suggests no apparent specific role for the trace elements in the drug function, parallels are drawn between the known drug related functions of Rb, Zn, Br, Fe, Co and K and the levels of elements found in the natural drugs. It is concluded that the various natural drugs also provide human benefits through supplements of essential elements such as Fe, Zn, Cr, Sc, Rb and Co.     

Determination of toxic elements in coal by ICP-MS after digestion using microwave-induced combustion

A microwave-induced combustion (MIC) procedure was applied for coal digestion for subsequent determination of As, Cd and Pb by inductively coupled plasma mass spectrometry (ICP-MS) and Hg using cold vapor (CV) generation coupled to ICP-MS. Pellets of coal (500 mg) were combusted using 20 bar of oxygen and ammonium nitrate as aid for ignition. The use of nitric acid as absorbing solution (1.7, 3.5, 5.0, 7.0 and 14 mol L⁻¹) was evaluated. For coal samples with higher ash content, better results were found using 7.0 mol L⁻¹ HNO₃ and an additional reflux step of 5 min after combustion step. For coal samples with ash content lower than 8%, 5.0 mol L⁻¹ nitric acid was suitable to the absorption of all analytes. Accuracy was evaluated using certified reference material (CRM) of coal and spikes. Agreement with certified values and recoveries was better than 95 and 97%, respectively, for all the analytes. For comparison of results, a procedure recommended by the American Society of Testing and Materials (ASTM) was used. Additionally, a conventional microwave-assisted digestion (MAD) in pressurized vessels was also performed. Using ASTM procedure, analyte losses were observed and a relatively long time was necessary for digestion (>6 h). By comparison with MAD procedure, higher sample mass can be digested using MIC allowing better limits of detection. Additionally, the use of concentrated acids was not necessary that is an important aspect in order to obtain low blank levels and lower limits of detection, respectively. The residual carbon content in digests obtained by MAD and MIC was about 15% and <1%, respectively, showing the better digestion efficiency of MIC procedure. Using MIC it was possible to digest completely and simultaneously up to eight samples in only 25 min with relatively lower generation of laboratory effluents.     

Determination of trace elements in honey by INAA in Turkey

Instrumental neutron activation analysis was applied to the determination of As, Cr, Sb, K, Br, Zn, Fe, Co in Turkish honey. Irradiation time was 6 h underwater at a thermal flux of 10¹³ n cm^–2 s^–1; cooling times of 100 h and 3–4 weeks and counting times of 5000 s and 80.000 sec were used. The detection limit for As is 0.01 ppm for honey matrix under these conditions. A technique was developed for sealing the quartz tube containing the honey with flame.     

Determination of rare earth elements in rice by INAA and ICP-MS

In order to improve the accuracy of reactor neutron activation analysis, flux gradients and spectrum changes in the irradiation capsule have been studied at the Kyoto University Reactor (KUR). The flux and spectrum monitoring samples of Fe, Co, Au, Sb, U and Ni were placed at several positions in a polyethylene irradiation capsule of 24 mm inner diameter and 98 mm length, and were irradiated in a pneumatic irradiation facility (Pn-2). The flux gradients were found to be rather negligible in the vertical (axial) direction while they were considerable in the radial one. The flux gradient was around 5%/cm for thermal neutrons and 10%/cm for epithermal and fast neutrons. The spectrum changes were dependent on the materials (polyethylene and silica) filled in the capsule. Based on these observations, the effect of the flux gradients and spectrum changes on the accuracy of reactor neutron activation analysis was discussed.     

INAA for the determination of trace elements and evaluation of their enrichment factors in lichens of high altitude areas

Sorption of lead(II) on very poorly soluble hexacyanoferrates(II) of transition metals: Cu^II, Ni^II, Zn^II, Co^II and on the ion-exchange composite obtained by mixing of nickel(II)-potassium hexacyanoferrate(II) with sulfonated phenolic resin serving as matrix was studied. Sorption was performed from solutions of hydrochloric acid at concentrations ranging from 10^–4 to 10^–1 mol·dm^–3. Analytical distribution coefficients for lead(II) sorption on these adsorbents were determined. Lead(II) sorption on Dowex 50 and the composite resin was studied as well.     

14 MeV INAA nitrogen determination in coal conversion liquids

Fast neutron activation analysis has been used for the direct determination of nitrogen in coal conversion liquids. In our previous work on coals, solid standards such as N-1-naphthylacetamide. NBS SRM 912 urea and NBS SRM 148 nicotinic acid were used for nitrogen determinations. In this work, a set of organic liquids was selected and evaluated for use as nitrogen standards in the analysis of coal-derived liquids. The use of the liquid standards minimizes problems associated with maintaining uniform irradiation and counting geometries and self absorption differences related to varying matrix densities. The standard liquids were selected using criteria of high boiling point, well-defined stoichiometry, high-purity, non-hygroscopic nature and simple C−H−N elemental compositions. Excellent agreement between the 14 MeV INAA data and calculated stoichiometric values has been demonstrated for liquids with nitrogen contents from 1.89 to 39.95%. The liquid standards have been used to determine nitrogen in a set of typical coal conversion liquids and several international standards.     

Determination of trace elements in Wuxi fallen ice by INAA

The concentrations of 14 elements, including Ir, Au, Co, Cr, Fe, Sr, Rb, K, Ta, Zn, Sb, Ba, Sc and Se, in the Wuxi fallen ice were determined by neutron activation analysis. The experimental results show that the relative concentration ratios of Ir/Co, Ir/Cr and Ir/Sc etc. in the ice water (0.0069, 0.00024 and 0.11, respectively) are quite close to those of Type C1 chondrite (0.0102, 0.00021 and 0.092, respectively), which implies that the fallen ice might be a piece of extraterrestrial substance.     

INAA and ETAAS of toxic element content of fruits harvested and consumed in Pakistan

Instrumental neutron activation analysis (INAA) and electro-thermal atomic absorption spectrometry (ETAAS) were employed to determine the toxic elements in fourteen fruits harvested in Pakistan. As, Br, Hg, Sb and Se were determined using INAA. Cadmium and Pb were determined using ETAAS. The intake levels of all toxic elements have been calculated. The data show that dates supply the maximum amount of most of the toxic elements. Peels of apple and pear have also been investigated and were found to contain higher concentration of toxic elements than their edible parts. The reliability of the techniques has been established by the use of standard reference materials. This study shows that all investigated fruits cultivated and consumed in Pakistan are safe for human consumption.     

Trace elements in the hair of new-born infants by INAA

Hair has been used as a bioindicator, as a means to measure environmental and occupational contamination, and a a tool for individualization in the forensic field. Because hair is a product of human metabolic activities, its elemental content is of interest in the examination of normal (healthy) metabolism and abnormal (diseased) metabolism. Employing hair analysis, sources of environmental pollution can be identified. Some recent INAA hair measurements were carried out in our laboratory. Hair samples of six new-born infants and their mothers were collected, washed, and analyzed according to standard procedures. By 5-minute irradiation (flux 2.5×10¹¹ n·cm^–2·s^–1) and gamma spectrometric analysis of hair and standard samples, elemental concentrations of Mg, Mn, Cu, Na, V, S, Al, Ca, and the halides were determined. Hair analysis of new-born infants should be of special interest, because it most likely represents endogeneous contribution. Hair assays of mothers and babies may prove to be clear mirrors which reflect observations pertaining to environmental metal mobilization and internal metabolic conditions. This work presents, along with a review of the subject, the results of a case study and identifies areas where further research is needed.     

The determination of trace elements in active charcoal by INAA

Neutron activation followed by X-ray spectrometry with magnetic deflection of -rays was applied to the nondestructive determination of Co, Cu and Br in active charcoal.     

Frequency of concentrations of some trace elements in serum by INAA

Concentration levels of eight trace elements in 120 samples of human blood serum were investigated by Instrumental Neutron Activation Analysis (INAA) for the purpose of medical research. The elements Co, Cr, Cs, Fe, Rb, Sc, Se, and Zn were simultaneously determined by the relative method in comparison with inorganic standards treated under identical conditions. The process of analysis and its reliability was checked using human serum and IAEA certified reference material. Statistical results are expressed in ppm or ppb. Both normal and, if necessary, log-normal frequency distributions of all elements determined are presented, types of distribution curves are verified statistically on 95% level of probability.     

Determination of trace elements in Na-bentonitic clay by INAA in Turkey

Instrumental neutron activation analysis was applied to the determination of trace elements in a Na-bentonitic clay. The irradiation was done in the Triga Mark II type reactor of ITU Nuclear Energy Institute. The sample was irradiated in two steps for short- and long- lived isotopes. After irradiation, spectra were taken using a germanium detector, multichannel analyzer Canberra System 100 and a fitting program called Sampo 90. The spectra of short-lived isotopes were analyzed to determine Al, Mg, Na, K, Ca, Ti elements and Mn, V trace elements. The spectra of long-lived isotopes were analyzed to determine Sc, Br, Sb, Cs, La, Ce, Sm, Yb, Hf, Pa, Np trace elements.     

Composition and origin of trace elements in fog water studied by INAA

Characterization of dilute solution of gamma-irradiated polymethyl methacrylate (PMMA) in acetone has been carried out. The polymer sample in form of natural beads was administered a gamma-ray dose of 30 kGy by a cobalt-60 radiationsource. Various types of viscosities, viscosity average molecular weight, shape and size of irradiated PMMA and its two fractions were calculated. The results were compared with those for unirradiated PMMA. Degradation of PMMA as a result of irradiation has been observed.     

Determination of some trace elements in the thyroid gland by INAA

Neutron activation analysis without radiochemical separation was used for simultaneous analysis of eight trace elements in thyroid glands, obtained as necroptic material from persons not suffering from diseases of this gland. Inorganic standard solutions were used for calculations of concentrations of measured elements. Concentrations are expressed in ppm, or ppb. IAEA reference materials were used for quality assurance of analyses. From analyses of 42 thyroids concentration levels of Se, Cs, Sc, Fe, Cr, Zn, Co, and Rb and their variances in the thyroids were calculated. These results might serve as comparison material for medical research of pathological and functional changes in thyroid glands.     

Analysis of toxic and radioactive components in sedimental type air particulates by INAA and XRF

The chemical composition of brown coal fuels and several sedimental type atmospheric particulate pollutants of industrial origin (e.g. fly-ash, bottom-ash, dust particulates from foundry-halls and casting-halls) was studied in relation to their toxic and their natural radioactive contents. In addition, some agricultural crops (e.g. soya bean, sunflower, rape, barley and luceme) sampled, in the near vicinity within a radius of about 10 km of the industrial centre were also analysed for significant distributions of any toxic components. Because of the high uranium and thorium concentrations in Hungarian coal fuels and, consequently, in various fly-ash particulate pollutants, the natural gamma activities of the samples were also measured and the relevant equilibriu states of the²³²Th and²³⁸U natural decay series were studied.     

Frequency of concentrations of some trace elements in scalp hair by INAA

126 samples of scalp hair from inhabitants of Central Bohemia were searched for content of zinc, cobalt, cesium, chromium, scandium, selenium, and iron, for the purpose of medical research. Simultaneous determination of the elements was made by INAA. Inorganic standards were used for calculation of concentrations of elements. Quality assurance was checked by IAEA certified reference material and by internal standard mixed human serum. Statistical results are expressed in ppm, or ppb. Both normal and, if necessary, log-normal distributions of elements are presented, and types of distribution curves are verified statistically on 95% level of probability.