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Summary  

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.

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Abstract  

The paper focuses on the validation of the k 0-method of instrumental neutron activation analysis (k 0-INAA) in the Tajura Nuclear Research Center (TNRC) via the analysis of several certified reference materials. The selected reference materials were: SRM 1572 Citrus Leaves, SRM 1575 Pine Needles, IAEA-A11 Milk Powder, IAEA-V-10 Hay Powder, RM IAEA-Soil-7 and RM IAEA-SL-1 Lake Sediment. The method is based on the PC version Kayzero/Solcoi software package issued by DSM. All the samples, reference materials and monitors were irradiated in various positions of the Tajura reactor with different f and α. The parameters f and α (f — thermal/epithermal neutron flux ratio, α — parameter accounting for the non-ideality of the 1/E epithermal neutron fluence rate distribution) were determined using the bare triple monitor method. The results obtained for all the reference materials are in good agreement with the certified values.

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Abstract  

The k 0-method of standardisation for instrumental neutron activation analysis (INAA) has been used at the OPAL research reactor to determine the elemental composition of three certified reference materials: coal fly ash (SRM 1633b), brick clay (SRM 679) and Montana soil (SRM 2711). Of the 41 certified elements in the three materials, 88 percent were within five percent of the certified values and all determinations were within 15 percent of the certified values. The average difference between the measured and certified values was 0.1 percent, with a standard deviation of 4.1 percent. Since these reference materials are widely used as standards in the analysis of archaeological ceramics by INAA, it has been concluded that the INAA facility in Australia is particularly well-suited for nuclear archaeometry.

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Abstract  

Cyclic neutron activation analysis method was conducted for determination of Se in food samples. High accuracy and good precision were proved by analyzing certified reference materials (CRMs) of chicken (GBW10018), rice (GBW10010) and cabbage (GBW10014). The detection limits for the three CRMs reached 0.16, 0.66 and 1.2 ng after 6 cycles at the 161.9 keV γ-peak from 77mSe, under a neutron flux of 9.0 × 1011 n cm−2 s−1 and the conditions of 30 s irradiation, 2 s decay, 30 s counting and 2 s waiting, significantly lower than those of conventional neutron activation analysis without any cycles, which were 0.94, 3.6 and 4.3 ng, respectively.

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Abstract  

A new Compton suppression system (CSS) for the gamma-ray spectrometer portion of the neutron activation analysis (NAA) was set up at the RPI/ITN. The pneumatic transfer system, SIPRA, for short-lived nuclides and cyclic irradiations was improved. A full calibration procedure of the CSS and SIPRA systems was performed. Two certified reference materials, NIST-SRM-1572 (Citrus Leaves) and NIST-SRM-1633a (Coal Fly Ash) were analyzed using the calibration factors. The CSS was instrumental in lowering the detection limits of Cr, Fe, Hg, Rb, Sr, Th and Zn by reducing background and/or spectral interference considerably. The analytical results were evaluated by comparison to the NIST certified values with deviations ranging from 2% to 8% for the above mentioned elements, except Zn ranging from 10% to 15% for biological and environmental samples, respectively.

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Abstract  

The three-stage BCR sequential step reference extraction procedure was applied to the reference material BCR CRM 601, especially developed for fractionation studies. Extracted fractions were analyzed for Cr, Ni, Zn, Cd, and Pb, by k 0-standardized instrumental neutron activation (k 0 INAA) and proton induced X-ray emission (PIXE), and flame atomic absorption spectrometry (FAAS). Sample preparation procedures were developed for both k 0 INAA and PIXE techniques, related to the evaporation of the solutions in order to get solid samples for neutron and proton irradiation. Quality control was assessed by intercomparison of the analytical results obtained by the applied techniques, which included results for a few certified reference materials. In the extracted fractions, chromium concentration was not determined accurately by both nuclear techniques. Concerning Cd, Ni, Pb, and Zn, the results were in general in good agreement with the certified values and FAAS. Some incomplete separation of the residue might have occurred.

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Abstract  

C, N, O, F and P can be analyzed by instrumental photon activation analysis (IPAA) including decay curve analysis. The interference of 30P (T 1/2 = 149.9 s) by 15O (T 1/2 = 122.2 s) can be ruled out by direct positron measurement making use of the largely different maximum β+-energies of both nuclides (3.24 MeV and 1.73 MeV, respectively). Interference by carbon (11C) can be avoided by sub-threshold activation with 17 MeV bremsstrahlung. The short half-life of 30P allows a high productivity of the method. Reliability was demonstrated in the range of 0.2%–2% P (detection limit = 40 μg/g). Analysis of a certified reference material (BCR-CRM 063) yielded excellent agreement with the certified data.

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Abstract  

Multielement determinations in the certified reference materials of soils (IAEA soil-5 and 7) have been studied fundamentally by instrumental photon activation analysis using the internal standard method coupled with the standard addition method. For the soil-5 sample, in the first place, the qualities of the comparative standards prepared by two processing methods were compared with each other. As a result, it was demonstrated that a highly accurate and precise multielement determination can be achieved easily by minor improvement in the processing method of the comparative standard to ensure homogeneity. The utility of this processing method for soil samples was proved further through a similar analysis in another soil sample (IAEA soil-7).

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Journal of Radioanalytical and Nuclear Chemistry
Authors: C. Chéry, S. Herremans, V. Van Lierde, F. Vanhaecke, M. Freitas, and R. Jasekera

Abstract  

Spices were analyzed by ICP-MS for determination of the ultra-micro trace elements in the human adult, Bi, Cd, Co, Ni, Pd, Pt, Se, Sn, Te, Tl, to complement previous results obtained by INAA and by EDXRF. The spices, originating from Sri Lanka, were curry, chilli powder and turmeric powders, coriander, cinnamon, black pepper, fennel, rampeh and curry leaves, and cumin. The analytical procedure was validated by analyzing the certified reference materials NIST SRM 1572 Citrus Leaves and NIST SRM 1573 Tomato Leaves. The results indicate that spices may contribute well to the daily optimal uptake of nutrients of a human adult. The adequacy of spices as a reference material with certified ultra micro trace elements is suggested.

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Simple and rapid analytical procedures for the AAS (Atomic Absorption Spectrometry) determination of Zn, Cd, Ni, Mo and Pb in biological, geological and soil samples are described. Special attention was paid to sample preparation, which is the step, most vulnerable to contaminants. Optimal conditions are presented for the wet digestion of plant matrices, products and waste for the coal treatment and soil matrices with different acids including: nitric, perchloric, hydrochloric, hydrofluoric, sulfuric and hydrogen peroxide along with optimal temperature programmes for subsequent electrothermal (ET)-AAS and flame (F)-AAS determination of Zn, Cd, Ni, Mo and Pb. Results of the analysis of all samples are discussed. The proposed method allows obviating the organic matrix (soil and plant) destruction stage, shortening the analyte dissolution time, reducing cost, and minimizing hazards of loss and contamination. The validity and versatility of the methods developed were verified by the analysis of certified reference materials.

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