Sodium polytungstate – sometimes referred to as Sodium metatungstate – is the inorganic compound with the formula Na6[H2W12O40], sometimes written 3Na2WO4·9WO3·H2O.
This salt is mainly used in the manufacture of dense aqueous solutions.
Due to its very high solubility in water (max. density 3.1 g/cm3), SPT is widely used as to produce “heavy liquid” for gravity separation (sink/float analysis) and density gradient centrifugation. It has significant advantages when compared to zinc chloride solution or the toxic halogenated carbons for sink-swim analysis. Aqueous SPT is non-toxic (unlike the denser Clerici solution), non-flammable, odorless, reusable and additionally it has a low viscosity.
ADVANTAGES:
• The inorganic salt sodium polytungstate results in an aqueous, neutral solution.
• SPT is a Non-Toxic high density agent.
• Has a low viscosity at high concentration.
• Easily adjustable densities from 1.0 g/ml to 4.2 g/ml
• Is ecology safe and simple to handle. Can be discarded easily.
• Has no obnoxious smell, no corrosive properties, not flammable.
• Stable in the pH-range of 2-14.
• Laboratory centrifuges can be used.
• Excellent recovery, substantially no losses and thus SPT is less expensive than TBE.
APPEARANCE:
• SPT makes a light yellow solution.
• Sodium Polytungstate (SPT) is available in powder.
FIELDS OF USE:
• Mineral Separation, Conodont Research and Earthquake Research.
• Density Gradient Centrifugation.
• As an inactive, non radioactive simulant in nuclear reactor technology.
• Separation of not soluble materials having different densities, like separation of minerals from gangue.
AQUEOUS SOLUTIONS:
When using and mixing Aqueous Solutions, ensure to use only distilled or deionized water. If you are storing the solution in containers, ensure to seal them appropriately. It is advised to use glass, plastic, or stainless steel containers for this purpose.
Exercise caution to prevent the solution from coming into contact with reducing agents such as base metals. In the event of such contact, blue discoloration may occur, but it will not affect the adjusted density or quality. To remove the blue coloration or prevent it from occurring, simply add a few drops of hydrogen peroxide.
Please note that your sink-float substance should be free of water-soluble ions. Occasionally, Pb2+, Ag+, Sn2+, and Ba2+ ions can form persistent precipitates either immediately or over time. If your samples contain these soluble ions, it is advised to thoroughly wash them with hot water beforehand.
SAFETY INFORMATION:
| ph value | approx.. 3 at 20°C |
| Melting point/freezing point | cannot be determined (decomposition) |
| Initial boiling point and boiling range | not applicable (solid) |
| Flash point | not applicable |
| Flammability (solid, gas) | not applicable |
| Explosive limits | not relevant |
| Vapour pressure | not relevant |
| Relative density | 5,47 g/cm³ at 20°C |
| Viscosity | approx. 60 mPa•s (solution with density 3.1 g/cm³) |
| Bulk density | approx. 1570 kg/m³ |
| Solubility in water | > 1000 g/l at 20°C |
| Surface tension | 73,4 mN/m at 20°C and 1254 mg/l |
| Partition coefficient n-Octanol/H2O | < -5,2 at 20°C |
| Auto-ignition temperature | not applicable |
| Explosive properties | none |
| Oxidising properties | none |
