Authors:R. Dybczyński, M. Wasek, and H. Maleszewska
A highly accurate and precise procedure deserving the name of definitive method has been devised for the determination of copper in biological materials. The method is based on combination of neutron activation and very selective and quantitative post-irradiation separation of copper from other radionuclides by extraction chromatography, using columns with LIX 70 on Bio-Beads SM-1, followed by gamma-ray spectrometric measurement. All potential sources of errors were carefully examined and eliminated or appropriate corrections were introduced into the procedure. The method contains several warning mechanisms safeguarding against making gross errors. Limit of detection for rather short irradiation time (tir
1 h) (which enables radiochemical work without sophisticated shielding) amounts to 15 g/kg. Results for copper concentration in several NBS, IAEA and other certified reference materials are presented and a new recommended value for IAEA's Milk Powder (A-11) is proposed.
A new method for the selective radiochemical separation of cadmium from other elements, present in biological materials, using amphoteric ion exchange resin Retardion 11A8 has been elaborated. Cadmium can be taken up by the resin either as anionic chloride complexes or cationic ammine complexes, depending on the composition of the eluent, exploiting both cation and anion exchange functions of the ion exchanger. The conditions in which Cd is quantitatively retained and eluted from Retardion 11A8 were established. The method of selective isolation of cadmium was further used for the determination of Cd in three biological certified reference materials by neutron activation analysis. Analytical results obtained with the use of the proposed separation procedure show good agreement with the certified values.
Authors:M. Carmo Freitas, L. Moens, P. De Paepe, and J. Seabra E Barros
A 7 kg stone of a Carrara marble was reduced to grains smaller than 100 m, mixed and homogeneized in order to prepare a marble reference material. The homogeneity was tested for 16 elements by instrumental neutron activation analysis (INAA). Through a one-way analysis of variance based on several analyses of each of 15 bottles and within the same bottle, it was concluded that the inter-bottle heterogeneity is not greater than the intra-bottle heterogeneity. Results on the concentration of major and trace elements in the marble reference material, obtained by different laboratories and different techniques, are given. The limestone certified reference material KALKSTEIN KH was used to evaluate measurement accuracy, to intercalibrate laboratories, and to provide compatibility of measurement data.
Chromium is one of the most difficult elements to accurately determine at the naturally occuring, ultratrace levels normally found in uncontaminated biological samples. In view of the importance of Cr, both as an essential and as a toxic element, efforts have focused on developing a simple, yet reliable, radiochemical procedure for Cr determination using neutron activation analysis. A number of problem areas have been identified in earlier methods, and an improved radiochemical separation procedure, based upon the liquid/liquid extraction of Cr(VI) into a solution of tribenzylamine/chloroform, has been developed. The fast neutron interference from Fe has been evaluated for the highly thermal RT-4 facility of the NBS Research Reactor, and Cr concentrations have been determined in samples of whole human blood collected under clean conditions and in two certified reference materials.
A new assembly dedicated for the low-level ψ-ray spectrometric measurements of environmental samples have been installed recently
at the International Atomic Energy Agency's Laboratories, Seibersdorf. Calibration of the detection efficiency was performed
by a set of 14 IAEA Certified Reference Materials, a standardized solution of134Cs, solutions of 2 pure potassium salts, and 2 mixed radionuclide gamma reference standard solutions. These materials, in
1.3 liter Marinelli beakers, were measured by a large HPGe detector. The high precision and accuracy of the calibration procedure
is shown by the high significance achieved in the linear fits of the efficiency results, which are traceable to certified
and standard reference materials. Small biases between some calibrands were detected. A new corrected result is the 1.37±0.05
Bq/kg activity concentration of137Cs in IAEA-A-14 Milk Powder.
Authors:M. Oladipo, J. Lori, J. Bonire, and O. Ajayi
Instrumental neutron activation analysis (INAA) technique has been employed viak0 approximation method to determine elemental composition of five shaving powders commonly marketed in Nigeria. Fe displayed the highest concentrations in the range 1000–2000 g·g–1. Na and Zn concentrations were established in the range 200–400 g·g–1. Heavy elements like Ga, La, Cr, Co, Ag, Ce and Nd concentrations were noted in the lower range of 1–10 g·g–1 Br, As, Sb, Sm, Eu, W, Cs, Tb, Yb, Hf, Ta, Th and U concentrations were established in even lower traces in the <1 g·g–1 range. Results obtained for a certified reference material, CANMET BL-1 and CERT (in house) Kaolin standard compared favourably with the literature values thus establishing the results presented for the shaving powders.
The assessment of environmental pollution of the coastal areas of the Malaysian Peninsula was done by analyzing the contents of the heavy and trace elements in the bivalves blood clams (Anadara granosa) and green mussels (Perna viridis) and sediments at twenty-two sampling stations to look for prevailing trends. Heavy and trace elements analyzed in this study were As, Cd, Cr, Cu, Pb, Se and Zn. Two techniques, namely the neutron activation analysis (NAA) and atomic absorption spectrophotometry (AAS) were used in the quantitative determination of the heavy metals while Marine Sediment Reference Material (BCSS) and Lobster Hepatopancreas (TORT-1) provided the certified reference materials in the quality assurance control. The potential use of these bivalves as suitable bio-indicators was evaluated from correlation tests based on the concentrations of heavy and trace elements in the sediment-metals system to those in the bivalves.
Authors:M. Menezes, C. Sabino, M. Franco, G. Kastner, and E. Rossi
Since 1995 the k0 instrumental neutron activation analysis has been applied at Radiochemical Laboratory, CDTN/CNEN, Brazil, by means of TRIGA MARK I IPR-R1 research reactor. At that time , f, and Tn were determined and the most recent determination of these parameters confirmed the great stability of the reactor along these years. In order to verify the efficiency and accuracy of the method, several certified reference materials have been systematically analyzed. Participating in Intercomparison Exercises organized by IAEA has been an important, essential and useful procedure to quality control. CDTN is the only Brazilian Institute to apply the k0-INAA to determine elements by means of their isotopes through short, medium and long half life using its own nuclear reactor.
Authors:E. G. Moreira, M. B. A. Vasconcellos, and M. Saiki
Instrumental neutron activation analysis was applied to evaluate the chemical composition of metallic materials, namely iron, steel, silicon and ferrosilicon certified reference materials. As, Co, Cr, Mn, Mo, Ni, V and W concentrations were analyzed in the iron and steel samples whereas 21 elements were determined in silicon and ferrosilicon samples. Accuracy and precision results of about 10% were achieved for most elements, indicating that the technique is suitable for the analysis of metallic materials. Interferences of Cr and Mn in V; Fe and Co in Mn; Co in Fe and Cr in Ti were quantified and only the last one was critical to the analysis of the materials employed in this work.
Foods collected for radionuclide analysis under the Food and Drug Administration's (FDA's) Total Diet Study (TDS) Program were analyzed by the Center for Food Safety and Applied Nutrition (CFSAN) as quality assurance (QA) for analyses performed at FDA's Winchester Engineering and Analytical Center (WEAC). 200-ml QA portions were analyzed for gamma-ray emitting fission products and naturally occurring radionuclides. Efficiency, pileup correction, absorption effects, and accuracy were determined by analyzing a variety of certified reference materials and KNO3 and KCl solutions. 40K results agreed well with those from WEAC and with total K results from other techniques. Count times as low as 2 minutes were sufficient to confirm that radioactivity concentrations were below regulatory limits.