Tungsten

Location:  Group 6, Period 6
Atomic Weight:  183.85
Coordination Number:  6, 7, 8, 9
Chemical Form in Solution:  WOF₅^-2 (chem. form as received)
(coordination numbers in green are observed less frequently)

Intended Use: For the calibration of analytical instruments and validation of analytical methods as appropriate.

Storage & Handling:  Keep tightly sealed when not in use. Store and use at 20 ± 4°C. Do not pipet from container. Do not return portions removed for pipetting to container.

Chemical Compatibility:  W is very readily hydrolyzed requiring 0.1 to 1% HF for stable acidic solutions. The [WOF₅]^-2 is soluble in % levels of HCl and HNO₃, provided it is in the [WOF₅]^-2 form. Stable at ppm levels with some metals provided it is fluorinated. Do not mix with Alkaline or Rare Earths. W is best to be mixed only with other fluorinated metals (Ti, Zr, Hf, Nb, Ta, Mo, Si, Sn, Ge). Look for yellow WO₃ precipitate if mixed with other transitions at higher levels indicating instability. The yellow WO₃ will form over a period of weeks even in trace HF, therefore HF levels of W multi-element blends should be ~ 1%.

Stability:  2-100 ppb levels stable (alone or mixed with all other metals that are at comparable levels) as the [WOF₅]^-2 for months in 1% HNO₃ / LDPE container. 1-10,000 ppm single element solutions as the [WOF₅]^-2 chemically stable for years in 1% HF in a LDPE container.

W Containing Samples (Preparation & Solution):  Metal (soluble in HF / HNO₃); Oxide (soluble in HF or NH₄OH); Organic Matrices (dry ash at 450 ⁰C in Pt⁰ and dissolve oxide with HF).