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. Commodity Code Description 28 09 10 Diphosphorus pentaoxide 28 09 20 Phosphoric acid and polyphosphoric acids