A rapid, low-blank technique for the extraction of osmium from geological samples

A new. rapid, low-blank method for extraction of osmium from geological mat erials is described. As with existing techniques, this new Os accumulation procedure relies upon the oxidation of Os in the sample solution to OsO4, a nd utilises the volatile nature of this oxide. In contrast to previous dist illation methods, however, osmium oxide is caught in a cold trap, coated on its inner surface with sulfuric acid instead of bubbling an Os oxide beari ng carrier gas through chilled HCl or HBr. Once the distillation is complet e, the trapped Os is extracted into 500 mul of HBr concentration and underg oes a final cleaning step which can be accomplished by employing convention al micro-distillation techniques. The entire extraction procedure from the sample solution takes approximately 90 min and requires only 2 mul of H,SO, to trap the osmium, which is achieved with great efficiency. Thus, apart f rom the digestion medium, the extraction and recovery of Os in this techniq ue employs a total of only similar to 502 mul of reagents instead of approx imately 5-10 ml in conventional procedures that 'see' the Os. As demonstrat ed here, the efficient extraction of Os and low reagent volumes required me an that it is possible to achieve yields of 80% and total procedural blanks of 100 fg routinely. (C) 2001 Elsevier Science B.V. All rights reserved.