Section III., 1915 [33] Trans. R.S.C. 



The "Ninhydrin" Reaction 



By Victor John Harding, D.Sc, Biochemical Laboratory, McGill 

 University, Montreal. 



Presented by Dr. R. F. Ruttan, F. R.S.C. 



(Read May Meeting, 1915). 



preliminary note 



The so-called "Ninhydrin" reaction is the formation of a blue 

 color when amino acids are heated with a solution of triketohydrindene 

 hydrate. This reaction was discovered by Ruhemann, (1) who found 

 it applicable to a number of a-amino acids, but if the amino acid was 

 substituted on the amino or carboxyl group, then a negative test 

 was obtained. jS and y amino acids responded only feebly to the test. 

 Ruhemann also investigated the chemistry of the reaction and identi- 

 fied the blue coloring matter produced as the ammonium salt of 

 diketohydrindylidene-diketohydrindamine, 



C6H4-CO (NH4O) C-C6H4 



- I I II I ' 



CO C = N^ C-CO 



and discovered that when alanine was the amino acid, it gave rise to 

 acetaldehyde and carbon dioxide. The reaction was quickly taken 

 up by Abderhalden (2) and his co-workers, who confirmed Ruhemann's 

 observations on the test, extended the list of reacting amino acids 

 and applied it as means of detecting pregnancy in addition to his 

 optical method. Thus it will be seen that the "ninhydrin" reaction 

 was used as a means of experimental support for Abderhalden's 

 theories on specific defensive ferments and as such combined with its 

 clinical applications, rose rapidly into prominence and importance. 

 Two papers, however, appeared strongly criticising the specific 

 nature of the "ninhydrin" reaction from a chemical point of view. 

 The first by Halle, Loewenstein, and Pribram, (3) stated that a blue color 

 was produced merely by heating anhydrous glycerol and triketo- 

 hydrindene hydrate to boiling for half a minute and that many alco- 

 hols aldehydes and ketones responded to the test in a similar manner. 



Sec. Ill, 1915—3 



