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 Griess diazotization reaction on which the Griess reagent relies was first described in 1858 by Peter Griess. The test is also been widely used for the detection of nitrates, which are converted to nitrites prior to applying the Griess test. Nitrates are common components of explosives.
When Sulfanilamide is added (or sulphanilic acid), the nitrite ion reacts to form a diazonium salt. When the azo dye agent (N-alpha-naphthyl-ethylenediamine) is formed a pink color 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.
The test involves the taking of a sample with ether and its division into two bowls. Sodium hydroxide is added to the first bowl followed by the Griess reagent; if the solution turns pink within ten seconds, this indicates the presence of nitrites. The test itself is positive if, after adding only Griess reagent to the second bowl, the solution there remains clear
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- Mick Hamer (1991-11-09). "Forensic science goes on trial: Even senior judges can be blinded by science". New Scientist. Retrieved 2007-08-07.