Application of a differential technique in inductively coupled plasma emission spectrometry: presentation of a relative reference measurement procedure for the determination of total mass fraction of uranium in mineralised rocks and similar matrices

Abstract

A relative reference measurement procedure for the determination of total mass fraction of uranium in mineralized rocks, ores and similar matrices using the application of a differential technique in inductively coupled plasma emission spectrometry at 409.014 nm wavelength is presented, based on the comparison of net reading or indication of reference ore solutions with a sample of similar but unknown mass fraction of uranium on the same sample weight or dilution basis. Under standard operating conditions of the instrument, ICP-OES measurements were performed at 409.014 nm wavelength after checking the instrument stability by C–Ar test, robustness of plasma and linearity response using aqueous standard U₃O₈ solutions. The estimated relative measurement uncertainty values obtained using the results of replicate analyses (“top-down” approach) in the ICP-OES procedure for mass fraction of uranium in low grade uranium ore IAEA samples and CANMET-reference uranium ore are S1, 0.0015; S2, 0.002; S3, 0.002; S4, 0.0015; and BL-2a, 0.001, respectively. Both approaches show low measurement uncertainty in the determination of total mass fraction of uranium without any chemical separation or extraction steps using a differential technique in the ICP-OES measurement procedure and are comparable with the differential technique in laser-induced fluorimetry (DT-LIF). Differential technique in spectrophotometry/laser fluorimetry/ICP-OES has inherent high metrological quality. Differential technique in the ICP-OES measurement procedure will be useful for the analysis of uranium in ores, certification of reference materials, borehole core assay, and other diverse applications in the nuclear fuel cycle.