Inductively coupled plasma atomic emission spectrometric studies for the determination of 233U in the Thorex process

Abstract

Inductively coupled plasma atomic emission spectrometric (ICP-AES) studies carried out for the determination of ²³³U in the presence of large amounts of thorium are described. Thorium was separated by precipitation as oxalate in 1 mol l^–1 HNO₃ medium (after ascertaining the thorium content) and maintaining an excess oxalic acid concentration of 0.01 mol l^–1 over the stoichiometric requirement. The supernatant was analysed by ICP-AES for ²³³U. A sensitive ²³⁸U spectral line of 385.958 nm with an isotopic shift of 0.008 nm for ²³³U and free from ²³²Th spectral line interference, was used for the analysis. A high resolution sequential spectrometer with an inductively coupled argon plasma excitation source was employed. The RSD was ±5% at 0.1 µg ml^–1233U. Based on these studies, a method can be developed for the routine monitoring of ²³³U at ppb levels in waste streams of the Thorex process.