Quality Assessment Statistic Evaluation of X-Ray Fluorescence via NIST and IAEA Standard Reference Materials

Abstract

The aim of this study is a quality assessment of X- ray fluorescence laboratory located at the University of Khartoum. The X - ray fluorescence spectrometer system consists, a set of three 109 Cd sources of an initial nominal activity of 10 μCi, and Si(Li) det ector Energy Dispersive XRF(EDXRF) systems. It is impo r- tant to carry out this work because it has an effective contribution for a wide range of research and services. The assessment was carried out by measuring 8 NIST- 2709a (soil) and 13 IAEA -155 (milk pow der) standard reference mat e- rial samples for repeatability examinations to test the measurement precision. The total combined standards uncertainty values for XRF lab were estimated by an error from repeatability measurements adding 2.6% for error propag a- t ion related to the method. For accuracy assessment, three standard statistic approaches were applied, i.e. the Bias %, zeta -score, and E n - number. The bias of all elements for both standard materials was found to be within a deviation range from −28% to 7.8%. The results of all elements for both the zeta - score test and E n - number have satisfactory results except Th (Thorium) and Zr (Zirconium ) which consider as questionable results for NIST SRM 2709a and unsatisfactory results for E n -number.