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The Griess test is an analytical chemistry test which detects the presence of nitrite ion in solution. One of its most important uses is the determination of nitrite in drinking water. The test has also been widely used for the detection of trace explosives containing nitro groups. It is usually necessary to release the nitrite ion from the organic explosive before analysis. This is normally done by alkaline hydrolysis. The ''Griess diazotization reaction'' on which the Griess reagent relies was first described in 1858 by Peter Griess. ==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 (in the picture its sulphonamide is shown instead), the nitrites form a diazonium salt. When the azo dye agent (N-alpha-naphthyl-ethylenediamine) is added a pink colour develops. This diamine is used in place of the simpler and cheaper alpha-naphthylamine because this latter is a potent carcinogen and moreover the diamine forms a more polar and hence a much more soluble dye in acidic aqueous medium. : A typical commercial Griess reagent contains 0.2% naphthylethylenediamine dihydrochloride, and 2% sulphanilamide in 5% phosphoric acid. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Griess test」の詳細全文を読む スポンサード リンク
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