Phosphomolybdic acid solution is primarily used in spectrophotometric determination of phosphate ions. PMA is also component in the 3-color histology stain called Masson's trichrome; employed in the differentiation step, Phosphomolybdic acid is one of the solutions fixed tissues are immersed in prior to subsequent staining. Phosphomolybdic acid is also used as reagent for simple and rapid colorimetric determination of phenothiazine derivatives. PMA oxidizes the phenothiazine derivative to a cationic free radical, forming a coloured salt. A preliminary extraction is necessary if certain reductants (sulphite or ascorbic acid) are present as stabilizers, as they will reduce the reagent to phosphomolybdenum blue.
Also available as dry reagent: Phosphomolybdic acid hydrate (sc-215711)
1. Fujinaga, T., et al. 1971. Talanta. 18: 960-962. PMID: 18960967
2. Stan, M., et al. 1977. Talanta. 24: 140-142. PMID: 18962047
3. Li, Y., et al. 2009. Org. Lett. 11: 2691-2694. PMID: 19514796