Quality Assurance for In Situ Uranium Concentration Measurements of Aqueous Samples from Mineral Processing Studies Using a Portable XRF Analyser in Compliance with ISO/IEC 17025 Requirements

Abstract

The method developed in this article aims to control the quality of uranium leaching and processing measurements at the Jordan Atomic Energy Commission, through the instant determination of uranium in aqueous samples without chemical preparation using portable X‐Ray Fluorescence (pXRF) analysis. Acidic and alkaline samples were analysed via pXRF then compared with results from ICP‐MS/ICP‐AES. The pXRF method validation, in view of ISO/IEC 17025:2017 requirements, was applied to real samples and simulated uranium ore solutions from single uranium and two other certified reference materials. The slopes acquired from correlations between pXRF results and reference values were 1.026, 1.021 and 0.9664, respectively, with correlation coefficients (r2) approaching 1.0. Precision calculations showed values < 5% RSD for samples having uranium contents > 10 mg l−1, while this value was ±10% at 5 mg l−1. The detection and quantification limits were determined as 2.5 and 7.7 mg l−1, respectively. Relative expanded uncertainty was found to equal 12.5% with a coverage factor k = 2 at the quantification limit. Finally, a paired t‐test and linear regression combining the pXRF results and reference values obtained by ICP‐MS and ICP‐AES demonstrated no significant difference at the 95% confidence level. This work eventually led to the laboratory’s ISO/IEC 17025:2017 accreditation for this method.