Method
Nitrite is detected and analyzed by formation of a red pink colour upon treatment of a NO2−-containing sample with the Griess reagent.
When sulphanilic acid is added, the nitrites form a diazonium salt. When the azo dye agent (alpha-naphthylamine) is added a pink colour develops.
A typical commercial Griess reagent contains 0.2% naphthylenediamine dihydrochloride, and 2% sulphanilamide in 5% phosphoric acid.
Read more about this topic: Griess Test
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