Colorimetric determination of tyrosine

Abstract

An improved method for the quantitative determination of tyrosine by the Gerngross-Voss-Herfeld (1933) reaction is described. Optimum experimental conditions were selected. The solution of [alpha]-nitroso-[beta]-naphthol was made in aqueous 0.1 N sodium hydroxide. The exclusion of ethanol from the reaction allowed stabilization of the color. Linearity of color response was obtained with solutions containing between 1 and 16 [mu]g of tyrosine/ml. The method can be used to estimate the tyrosine content of proteins.