Phosphomolybdic acid

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Phosphomolybdic acid
Phosphomolybdic acid.png
Phosphomolybdic acid crystals.jpg
CAS number 12026-57-2 YesY
51429-74-4 (hydrate)
PubChem 53384541
EC number 234-713-5
MeSH Phosphomolybdic+acid
Molecular formula H3PMo12O40
Molar mass 1825.25 g/mol
Density 0.94 g/ml
Boiling point 158 °C (316 °F; 431 K)
EU Index Not listed
Main hazards Flammable
Flash point 5 °C (41 °F; 278 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Phosphomolybdic acid, also known as dodeca molybdophosphoric acid or PMA is a component of Masson's trichrome stain. It is a yellow-green compound, freely soluble in water and polar organic solvents such as ethanol. It is used as a reagent in thin layer chromatography for staining phenolics, hydrocarbon waxes, alkaloids and steroids.

Conjugated, unsaturated compounds reduce PMA to molybdenum blue. The color intensifies with increasing number of double bonds in the molecule being stained.[1]

See also[edit]


  1. ^ Reduction of Phosphomolybdic Acid by Compounds Possessing Conjugated Double Bonds, S. Burstein, Anal. Chem., 1953, 25 (3), pp 422–424