This International Standard specifies a photometric method for the determination of the mass concentration of nitrogen oxides in exhaust gases from ducts or chimneys.

The method is applicable to the determination of the mass concentration of nitrogen oxides in exhaust gases from combustion processes, processes for surface treatment of metals and from organic chemical reactions, if necessary after removal by washing, in-furnace reduction and/or catalytic denitration, prior to their dispersion into the atmosphere.

This International Standard is applicable to the concentration range 5 mg/m³ to 1000 mg/m³ as NO₂ for a sample gas volume of 1000 ml.

For gas concentrations greater than 1000 mg/m³, the determination of sample gas concentrations up to 5000 mg/m³can be performed by diluting the sample solution or by taking an aliquot of the sample solution.

This International Standard is not applicable to the determination of dinitrogen monoxide (N₂O).