A new color test for tryptophan and related compounds.

It has been reported in a preliminary communication (1) that under certain conditions, at room temperature, perchloric acid converts tryptophan to a yellowish green fluorescent compound. Fluorescence was found to be particularly strong in ultraviolet light. It has now been found that a small amount of bichromate very considerably increases the sensitivity of this reaction and that the test may also be applied to certain compounds which are related to tryptophan. This reaction, however, is not given by any amino acid other than tryptophan. Tryptophan may thus be readily identified in untreated proteins.