Abstract
An enzymic method is described for the estimation of L-tryptophan in biological material, in the range 1-60 [mu]g. L-Tryptophan is converted quantitatively into indole by the enzyme tryptophanase, and the indole measured colorimetrically, after extraction with light petroleum, with either p-dimethylaminobenzaldehyde or p-dimethyl-aminocinnamic aldehyde reagents.