Section 06 Products of the chemical or allied industries 28 Inorganic chemicals; organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or isotopes 28 09 Diphosphorus pentaoxide; phosphoric acid; polyphosphoric acids, whether or not chemically defined. 28 09 20 Phosphoric acid and polyphosphoric acids 28 09 20 00 Phosphoric acid and polyphosphoric acids Commodity Code Description 28 09 20 00 000 Phosphoric acid and polyphosphoric acids