The estimation of creatine and of diacetyl.

Voges & Proskauer [1898] observed that when strong alkali was added to broth cultures of certain species of bacteria there developed, after an interval of time, a pink colour. Subsequently the work of Harden [1906] and of Harden & Norris [1911] established that the chemical reaction responsible was one between diacetyl and creatine (or certain similar substances). Attempts to make the reaction quantitative [Walpole, 1911; Eggleton & Eggleton, 1928] were only partially successful. The reaction was further studied by Duliere [1929], Lang [1932] and Muller [1935], but it was the discovery by Barritt [1936], that o-naphthol greatly intensifies the colour, which made it possible for the first timne to use this reaction as a means of estimating either creatine or diacetyl. The present paper presents some additional facts about the reaction and methods of estimation based on it.