An ion chromatographic method for the separation and determination of thorium in uranium
mineralizations has been developed using a mixed ion-exchange column; IonPac CS5A containing
both cation and anion exchange sites. Selective separation of U(VI) and Th(IV) was performed by online
gradient elution using two mobile phases of composition 0.1 M (NH4)2SO4 / 0.1M HCl and 0.2 M
(NH4)2SO4 / 0.1 M HCl, respectively. Post-column spectrophotometric detection with 3 mM arsenazo III
was then coupled at 655 nm. The separation factors between U and Th ions were found to be dependent on
(NH4)2SO4 and HCl concentrations of the eluent constituents and to a much more extent on its flow rate.
The optimized developed method has been validated by its application for the analysis of both uranium
and thorium in a sample from Abu Rusheid mineralization that is considered as a reference material and
has then been used for the analysis of a mineralized sample from Abu Zeneima area.