Phosphoric acid

Phosphoric acid (CAS 7664-38-2), also known as orthophosphoric acid and designated E338 in food applications, is a mineral acid used across industrial, food, and pharmaceutical sectors.

Where is Phosphoric acid used?

• Food and beverage: acidifies carbonated soft drinks and acts as a flavor modifier
• Metal surface treatment: rust conversion and phosphate coating prior to painting or galvanizing
• Water treatment: phosphate dosing for corrosion inhibition in distribution pipelines
• Pharmaceutical and industrial cleaning formulations: pH adjustment and sequestrant
• These formulations stabilize active ingredients against metal ion interference.
• Cleaning of production equipment in the food industry.
• Binders for refractory and ceramic materials.
• Wastewater treatment.
• pH adjustment of water in industrial processes such as boilers and cooling towers.

Good to know: FEMA 2902 recognition supports its use in flavoring systems. Food-grade material meets FCC and E338 specifications; pharmaceutical-grade supply meets USP and Ph. Eur. requirements.

Formulation notes

• Reacts violently with bases.
• The 75% concentration is more fluid and easier to pump and dose at room temperature than more concentrated grades.

Typical specification

• Commercially available as aqueous solutions at various concentrations, most commonly 75%, 80%, and 85%.
• The wet process can include an additional purification step to obtain technical or food grade acids.
• The 85% commercial solution melts at 21°C and may solidify at low temperatures.

Regulatory status

• For transport, classified under UN hazard class 8 with packing group III.
• Solutions with <10% phosphoric acid are not classified under CLP.

Storage, packaging and handling

• Reacts with metals to release flammable hydrogen gas.
• Should be stored in a cool, dry, well-ventilated place away from direct sunlight, heat, ignition sources, and incompatible materials.
• Should be stored in the original, labelled, shipping container, tightly closed and properly labelled.

Frequently asked questions about Phosphoric acid

Which materials should be avoided in contact with phosphoric acid?

Do not transfer into unlined steel containers or leave in contact with metal fittings because it can attack metals.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.