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 has also been widely used for the detection of nitrates (N-oxidation state = 5+), which are a common component of explosives, as they can be reduced to nitrites (N-oxidation state = 3+) and detected with the Griess test.