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PHOSPHOTUNGSTIC ACID

MacsChem > Biological Stains > PHOSPHOTUNGSTIC ACID

Phosphotungstic acid (PTA) or tungstophosphoric acid (TPA), is a heteropoly acid. It typically forms as a hydrate, with the n = 24 variant being common, though it can be dehydrated to the hexahydrate(n = 6) The structure of Phosphotungstic acid exhibits a Keggin structure, identified by a central phosphorus atom adjacent to twelve tungsten atoms, linked by oxygen atoms. This anion shows full tetrahedral symmetry and involves bridging and terminal oxygen atoms. Further, it can be synthesized by reacting sodium tungstate dihydrate with phosphoric acid and hydrochloric acid. Besides it is thermally stable up to 400 °C and decomposes with increasing pH, forming diverse elements.

CAS No.: 12501-23-4

Synonyms: Tungstophosphoric acid; 12-Tungstophosphate hydrate; 12-Tungstophosphoric acid hydrate; Dodeca-Tungsto Phosphoric Acid.

Physical Properties
Chemical formulaH3PW12O40
IUPAC Name 12-tungstophosphate hydrate
Molecular weight 2,880.2 g/mol
SolubilityWater
Density 3.88 at 20℃
Chemical Properties
ColorColorless-grayish or slightly yellow-green
StateSolid Powder or Crystals
Melting point89 °C (192 °F)
Vapor pressure19.2hPa at 20℃
  • Catalysis: Phosphotungstic acid is helpful in several chemical reactions as a homogeneous and heterogeneous catalyst due to its high acidity and thermal stability.
  • Phosphotungstic Acid Hematoxylin: This histological stain was developed by Mallory in 1897. It colors tissues reddish-brown or blue and assists in differentiating cellular components as it binds with hematin to highlight structures like fibrin and collagen.
  • Electron Microscopy: Phosphotungstic acid is employed as a negative stain in electron microscopy.Due to its high electron density makes it active for staining viruses, polysaccharides, and other biological materials. It increases contrast by adsorbing to sample surfaces, yielding clearer imaging of fine structures.
  • Protein Precipitation: Phosphotungstic acid acts as a “universal” precipitant for proteins in the analytical process.
  • Uric acid detection: Uric acid reduces Phosphotungstic acid, which leads to a brown-colored compound. This reaction demonstrates the presence of uric acid and is a method to test for its presence in a sample.
  • Analysis: Phosphotungstic acid is used in gravimetric analysis of potassium and diverse analytical methods.
Pictograms :

Hazard Statements :

H302: Harmful if swallowed.
H314: Causes severe skin burns and eye damage.
H411: Toxic to aquatic life with long-lasting effects.

Precautionary statements :

P260: Do not breathe dust or mists.
P273: Avoid release to the environment.
P280: Wear protective gloves/ protective clothing/ eye protection/ face protection.
P301 + P312: IF SWALLOWED: Call a POISON CENTER/ doctor if you feel unwell.
P303 + P361 + P353: IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water.
P305 + P351 + P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present, and easy to do. Continue rinsing.

Phosphotungstic acid (PTA) or tungstophosphoric acid (TPA), is a heteropoly acid. It typically forms as a hydrate, with the n = 24 variant being common, though it can be dehydrated to the hexahydrate(n = 6) The structure of Phosphotungstic acid exhibits a Keggin structure, identified by a central phosphorus atom adjacent to twelve tungsten atoms, linked by oxygen atoms. This anion shows full tetrahedral symmetry and involves bridging and terminal oxygen atoms. Further, it can be synthesized by reacting sodium tungstate dihydrate with phosphoric acid and hydrochloric acid. Besides it is thermally stable up to 400 °C and decomposes with increasing pH, forming diverse elements.

CAS No.: 12501-23-4

Synonyms: Tungstophosphoric acid; 12-Tungstophosphate hydrate; 12-Tungstophosphoric acid hydrate; Dodeca-Tungsto Phosphoric Acid.

Physical Properties
Chemical formulaH3PW12O40
IUPAC Name 12-tungstophosphate hydrate
Molecular weight 2,880.2 g/mol
SolubilityWater
Density 3.88 at 20℃
Chemical Properties
ColorColorless-grayish or slightly yellow-green
StateSolid Powder or Crystals
Melting point89 °C (192 °F)
Vapor pressure19.2hPa at 20℃
  • Catalysis: Phosphotungstic acid is helpful in several chemical reactions as a homogeneous and heterogeneous catalyst due to its high acidity and thermal stability.
  • Phosphotungstic Acid Hematoxylin: This histological stain was developed by Mallory in 1897. It colors tissues reddish-brown or blue and assists in differentiating cellular components as it binds with hematin to highlight structures like fibrin and collagen.
  • Electron Microscopy: Phosphotungstic acid is employed as a negative stain in electron microscopy.Due to its high electron density makes it active for staining viruses, polysaccharides, and other biological materials. It increases contrast by adsorbing to sample surfaces, yielding clearer imaging of fine structures.
  • Protein Precipitation: Phosphotungstic acid acts as a “universal” precipitant for proteins in the analytical process.
  • Uric acid detection: Uric acid reduces Phosphotungstic acid, which leads to a brown-colored compound. This reaction demonstrates the presence of uric acid and is a method to test for its presence in a sample.
  • Analysis: Phosphotungstic acid is used in gravimetric analysis of potassium and diverse analytical methods.
Pictograms :

Hazard Statements :

H302: Harmful if swallowed.
H314: Causes severe skin burns and eye damage.
H411: Toxic to aquatic life with long-lasting effects.

Precautionary statements :

P260: Do not breathe dust or mists.
P273: Avoid release to the environment.
P280: Wear protective gloves/ protective clothing/ eye protection/ face protection.
P301 + P312: IF SWALLOWED: Call a POISON CENTER/ doctor if you feel unwell.
P303 + P361 + P353: IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water.
P305 + P351 + P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present, and easy to do. Continue rinsing.

FAQ's

The principle is that phosphotungstic acid stain involves a higher concentration compared to hematein. It specifically stains red-brown components while tungsten binds to blue constituents in the sample.

Phosphotungstic acid is prepared by reacting sodium tungstate dihydrate with phosphoric acid, acidified with hydrochloric acid.

Phosphotungstic acid is a heteropolyacid with the formula H₃PW₁₂O₄₀. It comprises tungsten and phosphorus atoms bound in a definite structure, known for its properties as a chemical compound.

The pH of a Phosphotungstic Acid (PTA) stain is typically around 3.2.

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