438081 Sigma-Aldrich

Phosphoric acid

Green Alternative

ACS reagent, ≥85 wt. % in H2O

Synonym: Orthophosphoric acid



Related Categories ACS Grade Acids & Bases, Acids, Acids & Bases, Alternative Energy, Analytical Reagents,
Quality Level   200
grade   ACS reagent
vapor density   3.4 (vs air)
vapor pressure   2.2 mmHg ( 20 °C)
  5 mmHg ( 25 °C)
assay   ≥85% (with NaOH, titration)
form   liquid
greener alternative product characteristics   Design for Energy Efficiency
Learn more about the Principles of Green Chemistry.
concentration   ≥85 wt. % in H2O
application(s)   NMR: suitable
impurities   Reducing substances, passes test
  ≤0.001% volatile acids (as CH3COOH)
color   APHA: ≤10
bp   158 °C (lit.)
mp   ~40 °C (lit.)
density   1.685 g/mL at 25 °C (lit.)
anion traces   chloride (Cl-): ≤3 ppm
  nitrate (NO3-): ≤5 ppm
  sulfate (SO42-): ≤0.003%
cation traces   As: ≤1 ppm
  Ca: ≤0.002%
  Fe: ≤0.003%
  K: ≤0.005%
  Mg: ≤0.02%
  Mn: ≤0.5 ppm
  Na: ≤0.025%
  Sb: ≤0.002%
  heavy metals (as Pb): ≤0.001%
SMILES string   OP(O)(O)=O
InChI   1S/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4)
Gene Information   human ... SRC(6714)


General description

Phosphoric acid (H3PO4), also known as orthophosphoric acid, is an inorganic acid. It has a wide range of industrial applications such as an intermediate to produce animal feedstock, to prepare stock solutions for workup procedures and to treat the metal surfaces for better adhesion of paint and resin coatings. In the food industry it is used as a preservative, an acidulant and flavor enhancer.

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Phosphoric acid may be employed as standard for the determination of phosphorus-31 nuclear magnetic resonance (31P NMR) chemical shifts of the common phospholipids. It may be employed in the following studies:
• As external standard for the analysis of lipid composition of human white matter by 31P NMR spectroscopy.
• As external standard during the acid-labile phosphorylation of histone H4 by 31P NMR spectroscopy.
• As reference standard to investigate the surface species present on silica/alumina-supported sodium phosphates by pre- and postreaction MAS31P-NMR and FTIR spectroscopies.
• As catalyst in the vapor-phase Fries rearrangement of phenylacetate at 623K over a series of surface modified and unmodified ZSM-5.
• As an eco-friendly reagent for the removal of protecting groups like tert-butyl carbamates, tert-butyl esters and tert-butyl ethers.


2.5, 6×2.5 L in PVC-coated bottle

500, 6×500 mL in PVC-coated bottle

Other Notes

Concentrated phosphoric acid is approx. 85% H3PO4 (aqueous).

Safety & Documentation

Safety Information

GHS05  GHS05
Signal word 
Hazard statements 
UN 1805 8 / PGIII
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable


Certificate of Analysis (COA)

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Certificate of Origin (COO)

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