Compliant with the environmental protection industry standards HJ/T195-2005, HJ/T197-2005, HJ/T198-2005, HJ/T199-2005, HJ/T200-2005 and other project standards of the People's Republic of China, the gas phase molecular absorption spectroscopy mechanism is used for the analysis of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total nitrogen and sulfides.