Abstract
1. Absorption curves of the coloured products by Ehrlich's reaction have been investigated.
2. By interacting of α-amino acids and sugars are produced substances which in turn give dyes with Ehrlich's reagent with absorption maxima around 520 mμ.
3. The α-amino acids, which have another amino group besides, give rise to more intense coloration than simple a-amino acids, and show an absorption maximum around 576 mμ.
4. Tryptophane and glucosamine do not give any compounds show-ing absorption in the visible region, when they interact with sugars.
5. Tryptophane and indole give positive Ehrlich reaction immediately, and the former shows an absorption spectrum with maximum at 550 mμ and minimum at 564 mμ, but the latter that with maximum at 572 mμ.
6. The colour developed by N-acetylglucosamine shows absorption maxima at 548 mμ and 586 mμ, while that by glucosamine after treatment with alakline acetylacetone possesses one single absorption maximum at 544 mμ.
Thanks are due to Mr. Masao Sumino of the Central Laboratory, Hitachi Co. for his enthusiastic co-operation in the course of this work.
