Section 06 Products of the chemical or allied 28 Inorganic chemicals; organic or inorganic compounds of precious metals, of rare earth metals, of radioactive elements or isotopes 28 04 Hydrogen, rare gases and other non-metals Commodity Code Description 28 04 10 - Hydrogen 28 04 21 - - Argon 28 04 29 - - Other 28 04 30 - Nitrogen 28 04 40 - Oxygen 28 04 50 - Boron; tellurium 28 04 61 - - Containing by weight not less than 99.99% of silicon 28 04 69 - - Other 28 04 70 - Phosphorus 28 04 80 - Arsenic 28 04 90 - Selenium