Improvements on the Separation Method of Osmium by Direct Distillation in Carius Tube

Distillation is a simple method for separating Os from the sample matrix. However, complicated apparatus and heavy cleaning work have been the major limitation to its application. In this paper, the Carius tube direct distillation apparatus was improved and simplified by using latex dripper to replace the silicone tube and glass end cap and an electric steamer to replace the electric jacket. The distillation time, dilution factor and volume of the trap solution were optimized. After the improvements, the heating rate, stability and simplicity of the apparatus were improved, the cleaning work was reduced significantly to obtain a lower blank level, and large batches of samples can be treated in a relatively small working space. The experimental results indicate that the Os recovery of this method ranges from 86.7% to 95.2%. After being distilled for 2 h, Os recovery of the Carius tube direct distillation was about 41% higher than that of the traditional distilling flask method. For different samples and testing instruments, corresponding distilling conditions can be chose to shorten the treating time and enhance the signal intensity. The dating results obtained from molybdenite reference materials GBW 04436 (JDC) and GBW 04435 (HLP) were (139.5±1.9) Ma -(142.0±2.1) Ma (n=5) and (220±3.3) Ma -(223.0±3.2) Ma (n=2), respectively, in good agreement with certified values of (139.6±3. 8) Ma for GBW 04436 and (221.4±5.6) Ma for GBW 04435. This method was applied as a routine method for Os separation.