Separation of hafnium from tungsten by extraction chromatography with TOA in HCl–H2O2 mixture

An efficient method for the removal of Pb prior to the ultra-trace Am measurement by ICP-MS

The existence of Pb which formed polyatomic ions such as PbCl+, PbAr+ would interfere the determination of ultra-trace Am by ICP-MS. An extraction chromatography method for the removal of Pb interference was provided in this work to improve the determination accuracy of ultra-trace Am by ICP-MS. In this study, Sr resin was applied to separate Am and Pb because of the great difference between Am and Pb on adsorption ability. The variable parameters including nitric acid concentration, loading volume, column height and loading amount were investigated to optimize the separation conditions for high recovery of Am (R(Am)) as well as high decontamination factor of Pb (DF(Pb)). The optimal separation method was recommended in the study with the recovery of Am over 99% and the decontamination factor of Pb over 2 × 105. Moreover, the method was successfully applied to the analysis of 241Am in the simulated samples.

On-line HfF5(-)/WF5(-) separation in an O2-filled radiofrequency quadrupole gas cell

RATIONALE

An experimental Isobar Separator for Accelerator Mass Spectrometry (ISAMS) instrument has been used to demonstrate an on-line separation of HfF5(-) from its isobar WF5(-). This is necessary, in addition to sample preparation chemistry, for measuring (182)Hf at natural levels by Accelerator Mass Spectrometry (AMS).

METHODS

The device utilizes a radiofrequency quadrupole (RFQ) controlled gas cell, wherein anion-gas reactions at eV energies attenuate the interfering isobars of the analyte molecular anions, leaving HfF5(-) for AMS analysis. The RFQ also helps to control the multiple scattering resulting from the ion-gas collisions.

RESULTS

O2 gas was used in the HfF5(-)/WF5(-) separation and WF5(-) was attenuated by nearly 3 orders of magnitude while maintaining ~75% transmission of HfF5(-). It is expected that the transmission and attenuation can be increased by further research.

CONCLUSIONS

This result advances the possibility of detecting natural (182)Hf when AMS is supplemented with an isobar separator in the injection system.