Development of a Primary Iridium Solution Standard Traceable to the International System of Units.

The purpose of this work was to develop a primary solution standard for iridium (Ir) that is directly traceable to the International System of Units (SI). The candidate starting material was ammonium hexachloroiridate hydrate, ((NH)IrCl·3HO), the Ir salt. The SI traceability of the Ir salt was established by the gravimetric reduction (GR) of the salt to the metal under H.

Tracing an Osmium Solution Standard to the International System of Units (SI).

The purpose of this work was to develop an accurate osmium (Os) solution standard that is traceable to the International System of Units, the SI. A gravimetric reduction (GR) method was developed to accurately assay the Os in ammonium hexachloroosmate salt, (NH)OsCl, the chosen starting material for the Os solution standard. This GR method was also applied to -200 mesh high-purity Os metal powder, which served as an independent source of Os for comparison.