Quality control and performance evaluation of k0-based neutron activation analysis at the Portuguese research reactor

The quality control (QC) and performance evaluation for the k(0)-based neutron activation analysis (k(0)-NAA) at the Portuguese research reactor (RPI) has been developed with the intention of using the method to meet the demands of trace element analysis for the applications in environmental, epidemiological and nutritional studies amongst others. The QC and performance evaluation include the following aspects: (1) estimation of the overall/combined standard uncertainty from the primary uncertainty sources; (2) validation of the method using a synthetic multi-element standard (SMELS); and (3) analysis of the certified reference materials from the National Institute of Standards and Technology (USA): NIST-SRM-1633a and NIST-SRM-1648 and the reference material from the International Atomic Energy Agency: IAEA-RM-336, for the purpose of controlling the overall accuracy and precision of the analytical results. The obtained results revealed that the k(0)-NAA method established at the RPI was fit for the purpose. The overall/ combined standard uncertainty was estimated for elements of interest in the intended applications. The laboratory's analytical results as compared to the assigned values with the bias were less than 12% for most elements, except for a few elements which biased within 13-18%. The u-score values for most elements were less than vertical bar 1.64 vertical bar, except for Co, La and Ti within vertical bar 1.64 vertical bar-vertical bar 1.96 vertical bar and Sc, Cr, K and Sb within vertical bar 1.96 vertical bar-vertical bar 2.58 vertical bar. The NIST-1633a was also analyzed over 14, months for the purpose of evaluating the reproducibility of the method. The quality factors of k(0)-NAA established at RPI were evaluated, proving that the method meets the requirements of trace element analysis, which is also considering the method's performance for which the k(0)-NAA affords a specific, rapid and convenient capability for the intended applications. (C) 2010 Elsevier B.V. All rights reserved.