1.1 This standard applies to the determination of nitrogen oxide in organized emission from stationary source.
1.2 When the sampling volume is 1L, the qualitative detection concentration by this method is 0.7mg/m3, and the quantitative determination concentration scope is 2.4~208mg/m3. Samples of higher concentration may be determined by dilution.
1.3 When the ozone concentration is 5 times larger than the nitrogen oxide concentration and the sulfur dioxide concentration is 100 times larger than nitrogen oxide concentration, the determination of nitrogen oxide will be disturbed.
2 Principle
Nitrogen oxides (NOx) include nitric oxide (NO) and nitrogen dioxide (NO2), etc. During sampling, suboxides in gas such as nitric oxide will be firstly oxidized into nitrogen dioxide by chromium trioxide, and after nitrogen dioxide is absorbed by absorption solution, nitrus acid and nitric acid will be generated, among which nitrus acid will have reoxidation reaction with sulfanilic acid and then couple with ethylenediamine dihydrochloride, which will show rose red, in this way spectrophotometric determination will be conducted according to the color.
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3 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard.
GB 16297-1996 Comprehensive Emission Standard of Air Pollutants
GB 16157-1996 Determination of Particulates and Sampling Methods of Gaseous Pollutants Emitted from Exhaust Gas of Stationary Source
