Elemental characterization of a candidate lichen research material — IAEA-336

A lichen research material, prepared from the species Evernia prunastri, was produced by a co-operation between the International Atomic Energy Agency (IAEA) and the Instituto de Ciencias e Engenharia Nucleares (INETI) in Sacavém, Portugal. An international intercomparison study was carried out, with 42 independent sets of results being reported from participants in 26 countries. The statistical evaluation of the collected data resulted in recommended values for 17 elements and information values for 15 elements. The criteria for assigning the values are provided, including the use of information obtained through the parallel analysis of a second material, IAEA-359, Cabbage.     

Participation in IAEA proficiency test exercise on major,minor and trace elements in ancient Chinese ceramic (IAEA-CU-2006-06) using low power research reactor

A proficiency test (PT) exercise was offered by the International Atomic Energy Agency (IAEA) for major, minor and trace elements in Chinese ceramic reference material (IAEA-CU-2006-06). Neutron activation analysis (NAA) laboratory at PINSTECH, Pakistan participated in the exercise and submitted the results for 28 elements. The aim of participation was to develop a suitable methodology for accurate measurement of as many elements as possible in ceramic material using a low power reactor (PARR-2) as this would help future investigation in a project on the authenticity of art objects, for provenance, conservation and management of ancient cultural heritage of the country. After receiving the final report of the PT exercise, a critical review of our data and final scoring of each element is made to check the suitability of our methodology and reliability of the acquired data. Most of the reported results passed different statistical evaluation criterion such as relative bias, z-score and u-scores and ratio of our results and IAEA target values. One element (Yb) falls in the unacceptable range of relative bias and z-scores. Hf and Tb showed slightly high z-scores within the questionable range. Ho, Mo and Sn were determined during this study but their results were not submitted to the IAEA. The confidence of accuracy observed for most of the elements in ceramic material has made it mandatory to report their results as information values.     

Certification of trace and major elements and methylmercury concentrations in a macroalgae (Fucus sp.) reference material, IAEA-140

A marine reference material, IAEA-140, prepared with a macroalgae (Fucus sp.) was recently produced by the International Atomic Energy Agency and certified for trace and major elements and for methylmercury (MeHg). Certification of this material was achieved as an outcome of an international analytical intercomparison study which resulted in 116 independent sets of results reported by participants from 54 countries. The statistical evaluation of the collected data and the criteria used for assignment of the mean and uncertainty values are described. The analysis of data allowed to certify concentration values for 24 elements and MeHg, and to provide information values for another 10 elements. Regarding the elements which could be given certified values, between two and eight different instrumental methods were used to measure metal concentrations, and four independent analytical procedures were used to measure MeHg concentrations. In order to assess the results of the certification procedure, a comparison was made between the certified values obtained from the world-wide intercomparison results and the values obtained from a small subgroup of well-qualified laboratories. The means and 95% confidence intervals for reference values obtained by the two methods are similar for most elements showing that the usual method of certification used by the IAEA, based on large groups of participants, is indeed pertinent.     

Simultaneous metal adsorption on tannin resins

Vegetable tannin sorbent is evaluated as ion exchange resin using a multitracer study on the adsorption behavior of various elements. Lisiloma latisiliqua L. tannins, polycondensated into spherical pellets were chosen as sorbent resin material. Sorption evaluation of Ce, Cu(II), U(VI), Eu, Fe(III), Th, Nd as representatives of different classes of metal ions were done at different pH values. The distribution ratio of the studied elements was calculated from laboratory experiments. Tannic ion exchange material shows excellent ability for actinides and rare earth elements adsorption from waters. Using radiotracers, the number of catechins subunits involve in each tannin-metal complex was determined.     

An accurate and simple universal curve for the energy‐dependent electron inelastic mean free path

The values of inelastic mean free paths (IMFPs) calculated from optical data for the three material categories of elements, inorganic compounds and organic compounds are re‐assessed to provide a simple equation giving an estimate of the IMFP, knowing only the identities of the elements in an analysed layer and the atomic density of that layer. This simple equation is required for quantification of the thicknesses for layers of mixed elements in which the required parameters for use of the popular equation, TPP‐2M, are insufficiently known. It describes the published values, calculated from optical data for energies above 100 eV, to a similar root mean square (RMS) deviation as that for TPP‐2M in the three material categories. The RMS deviation for all three categories averages 8.4%, provided the inorganic data are ‘corrected’ for the published sum rule errors. If, in an analysed layer, only elements are identified and the atomic density is unknown, i.e. only the average Z value of the layer is known, a simpler relation is provided for the IMFP in monolayers with only one unknown parameter Z that exhibits an RMS deviation from the IMFPs calculated from optical data of 11.5%. Copyright © 2011 Crown copyright.     

Certification of trace and major elements and methylmercury concentrations in a macroalgae (Fucus sp.) reference material, IAEA-140

A marine reference material, IAEA-140, prepared with a macroalgae (Fucus sp.) was recently produced by the International Atomic Energy Agency and certified for trace and major elements and for methylmercury (MeHg). Certification of this material was achieved as an outcome of an international analytical intercomparison study which resulted in 116 independent sets of results reported by participants from 54 countries. The statistical evaluation of the collected data and the criteria used for assignment of the mean and uncertainty values are described. The analysis of data allowed to certify concentration values for 24 elements and MeHg, and to provide information values for another 10 elements. Regarding the elements which could be given certified values, between two and eight different instrumental methods were used to measure metal concentrations, and four independent analytical procedures were used to measure MeHg concentrations. In order to assess the results of the certification procedure, a comparison was made between the certified values obtained from the world-wide intercomparison results and the values obtained from a small subgroup of well-qualified laboratories. The means and 95% confidence intervals for reference values obtained by the two methods are similar for most elements showing that the usual method of certification used by the IAEA, based on large groups of participants, is indeed pertinent.     

Analysis of FDA in-house food reference materials with anticoincidence INAA

In-house reference material (IRM) cocoa powder (CCP) has been in use at US Food and Drug Administration laboratories for about 15 years. A single lot of commercial material was originally characterized for 32 elements by several laboratories and five techniques. A unique approach for basis weight determination based upon ambient relative humidity was developed for CCP, eliminating the need for dry weight determinations. The CCP Reference Sheet is updated by incorporating new results approximately every 5 years. The last update occurred in 2006. As part of an effort to revalidate and update values for CCP, anticoincidence instrumental neutron activation analysis (INAA) was used to determine mass fractions for 16 of the originally characterized elements, as well as to provide information on 16 other elements. Results were in very good agreement with 2006 Reference Sheet values. A new candidate IRM, fresh-frozen swordfish (FFSF) powder, was produced by adding inorganic As, Cd, Cr, Hg, Pb, Sb, and Se to liquid nitrogen-frozen commercial swordfish filets which were then homogenized. Portions of FFSF were analyzed by INAA to provide mass fraction and homogeneity information for As, Cd, Cr, Hg, Sb, and Se as well as for eight other elements occurring naturally in the material. Non-homogeneities were ≤2.5 % for As, Br, Cd, and Cs, and ≤1.8 % for Cr, Hg, Rb, Sb, and Se. Certified reference materials DORM-3 Fish Protein powder and fresh-frozen SRM 1947 Lake Michigan Fish Tissue were analyzed as controls.     

Colon tissue concentrations of copper, iron, selenium, and zinc in colorectal carcinoma patients

Concentration of four trace elements (copper, zinc, iron, and selenium) was determined in colon tissue from twenty-three patients with colorectal cancer. The tissue samples were dried and dissolved using microwave-assisted digestion technique. The content of trace elements was determined using atomic absorption spectrometry. No significant differences between Zn levels in normal and cancerous tissues were observed. However, the levels of Cu, Fe, and Se were significantly higher in cancerous tissues than in the control samples. The results obtained sing microwave-assisted technique were compared to those obtained via alkaline digestion with tetramethylammonium hydroxide. Both techniques were used for the digestion of certified reference material of pork liver. Very good agreement with the certified values of Cu, Fe, and Zn in the reference material was achieved using alkaline digestion procedure. This technique seems to be an efficient alternative to decomposition of biological samples.     

Preparation and certification of hijiki reference material, NMIJ CRM 7405-a, from the edible marine algae hijiki (Hizikia fusiforme)

A certified reference material, NMIJ CRM 7405-a, for the determination of trace elements and As(V) in algae was developed from the edible marine hijiki (Hizikia fusiforme) and certified by the National Metrology Institute of Japan (NMIJ), the National Institute of Advanced Industrial Science and Technology (AIST). Hijiki was collected from the Pacific coast in the Kanto area of Japan, and was washed, dried, powdered, and homogenized. The hijiki powder was placed in 400 bottles (ca. 20 g each). The concentrations of 18 trace elements and As(V) were determined by two to four independent analytical techniques, including (ID)ICP-(HR)MS, ICP-OES, GFAAS, and HPLC-ICP-MS using calibration solutions prepared from the elemental standard solution of Japan calibration service system (JCSS) and the NMIJ CRM As(V) solution, and whose concentrations are certified and SI traceable. The uncertainties of all the measurements and preparation procedures were evaluated. The values of 18 trace elements and As(V) in the CRM were certified with uncertainty (k = 2).     

Determination of Trace Elements in Super Alloy by ICP-MS

 A method is described for determination of 14 trace elements in super alloy certified reference material. Inconel 718 by ICP-MS. The interferences were investigated in detail. By using appropriate settings of the operational parameters and correcting interferences the elements without interference free isotopes were also analyzed. Non-spectral interference to the analytes was studied. No matrix separation or any other sample pretreatment but acid dissolution was made. 14 trace elements (B, Sc, Ga, Ge, In, Sn, Sb, Te, Hf, Ag, Ce, Tl, Pb and Bi) were analyzed by matrix matched standard solution calibration and using Rh as internal standard. Good agreement was achieved between the found levels and the certified values for most of the elements. The RSD (n = 4) of the determination values of Ce was lower than 20%, and RSD of the other 13 elements was lower than 10%. Received July 21, 2000. Revision May 29, 2001.