Adamkiewicz reaction

The Adamkiewicz reaction is part of a biochemical test used to detect the presence of the amino acid tryptophan in proteins. When concentrated sulfuric acid is combined with a solution of protein and glyoxylic acid, a red/purple colour is produced. It was named after its discoverer, Albert Wojciech Adamkiewicz.[1][2] Pure sulphuric acid and a minimal amount of pure formaldehyde, along with an oxidizing agent introduced into the sulphuric acid, allow the reaction to proceed. In this oxidation-reduction reaction, the oxidizing agent can be sodium amalgam, which reduces oxalic acid, while the reducing agent is nitric acid, which oxidizes an alcohol. Reduction of the oxalic acid is done in a sulphuric acid solution while avoiding a temperature increase inside the cathode. Once the reduction has ended, the oxalic acid is diminished and the freed glyoxylic acid produces the indol molecules, which gives the red/purple color.[3]