Product Code Database
The Griess test is an analytical chemistry test which detects the presence of nitrite ion in aqueous 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.Peter Griess (1858) "Vorläufige Notiz über die Einwirkung von salpetriger Säure auf Amidinitro- und Aminitrophenylsäure," (Preliminary notice of the reaction of nitrous acid with picramic acid and aminonitrophenol), Annalen der Chemie und Pharmacie, 106: 123–125. The test has also been widely used for the detection of (N-oxidation state = +5), which are a common component of , as they can be redox to nitrites (N-oxidation state = +3) and detected with the Griess test.
The Griess test involves two subsequent reactions. When sulfanilamide is added, the nitrite ion reacts with it in the Griess diazotization reaction to form a diazonium salt, which then reacts with N-(1-naphthyl)ethylenediamine in an azo coupling reaction, forming a pink-red azo dye.
Using a spectrophotometer, it is possible to quantitatively determine the nitrite concentration. The detection limit of the Griess test generally ranges between 0.02 and 2 μM, depending on the exact details of the specific components used in the Griess reagent.
The test involves the taking of a sample with ether and its division into two bowls. Caustic soda 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.
The convictions of Judith Ward and the Birmingham Six were assisted by Frank Skuse's flawed interpretation of Griess test results.
|
|
