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 33 Sulphates; alums; peroxosulphates (persulphates). 28 33 40 Peroxosulphates (persulphates) Commodity Code Description 28 33 40 00 Peroxosulphates (persulphates)