미국
SRM 3163 Tungsten (W) Standard Solution, Lot No. 140606
This Standard Reference Material (SRM) is intended for use as a primary calibration standard for the quantitative determination of tungsten. A unit of SRM 3163 consists of 50 mL of an acidified aqueous solution prepared gravimetrically to contain a known mass fraction of tungsten in a high-density polyethylene bottle sealed in an aluminized bag. The solution contains nitric acid at a volume fraction of approximately 7 % and hydrofluoric acid at a volume fraction of approximately 4 %, equivalent to amount of substance concentrations (molarities) of approximately 1.2 mol/L and 1.1 mol/L respectively. This data is public in the Certificate of Analysis for this material.