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

In order to measure 182Hf by accelerator mass spectrometry (AMS), a chemical procedure for separation of hafnium from tungsten has been developed by extraction chromatography. The extraction chromatographic behavior of hafnium and tungsten has been studied using tri-n-octylamine (TOA) as the stationary phase, HCl-H2O2 mixture and NH3 · H2O as the mobile phase. The effects of H2O2 concentration, column loading and column dimensions are investigated. Hf and W with microgram amounts are successfully separated on a chromatographic column (diameter 5 x 196 mm), on which Hf is hardly retained after completely eluted with 6 M HCl-1% H2O2 and W strongly adsorbed is then eluted with 3 M NH3 · H2O. The decontamination factor for tungsten is 3.0 x 105 and the recovery of hafnium is better than 99% using a single column separation. (author)