A new reagent for the assay of indole in the tryptophanase reaction

Abstract

Details are presented of a modified procedure for the extraction of indole into light petroleum from aqueous tryptophanase reaction systems. The use of p-dimethylaminocinnamal-dehyde as a reagent for indole is described, and factors affecting the rate of color formation, color density and stability are described. The quantitative use of this reagent is compared with that of Ehrlich reagent. The sensitivity increase under the conditions selected is greater than 2.2, and the reagent is capable of assaying amounts of indole greater than 1 ug contained in 20 ml of aqueous solution.