Isotopic uranium determination by inductively coupled plasma atomic emission spectrometry using conventional and laser ablation sample introduction

Abstract

The use of inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of ²³⁵U: ²³⁸U isotope ratios in U–Zr metal alloys (90% m/m U, 10% m/m Zr) is described. Conventional pneumatic nebulization and laser ablation sample introduction techniques were utilized. The results of the determination agreed, within experimental uncertainty, with isotope ratios determined by thermal ionization mass spectrometry (TIMS), e.g., ²³⁵U: ²³⁸U for conventional nebulization = 2.091 ± 0.006, for laser ablation = 2.092 ± 0.015 and for TIMS = 2.0940 ± 0.0004. The precision, i.e., the relative standard deviation (RSD), of the sequential determination of the intensities of the ²³⁵U and ²³⁸U components of the U emission line and the resultant isotope ratios was improved significantly by the use of an intrinsic internal standard (Zr), i.e., RSD = 1.6% to RSD = 0.17%.