Forensics
The test was used in forensics for many years to test for the traces of nitroglycerine.
Caustic soda is used to break down the molecule of nitroglycerine to produce nitrite ions. The concentration of this caustic soda is crucial to the test.
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
Due to the ability of many substances to produce nitrite ions, the test is not conclusive and eventually proved of limited value. British police forces had practically stopped using it by the mid-1980s.
The convictions of Judith Ward and the Birmingham Six were assisted by Frank Skuse's flawed interpretation of Griess test results.
Read more about this topic: Griess Test