Abstract
An improved method for the Millon reaction using cupric ion together with mercuric ion is presented for the determination of tyrosine. Blue-violet coloration in the present method is based on the mercuration and nitrosation of tyrosine, according to the conventional Millon reaction, followed by the chelate formation of nitrosotyrosine with cupric ion. This method is more sensitive than the conventional reaction, and the colored substance is more stable than that formed by the conventional reaction, and the colored substance is more stable than that formed by the conventional method. The colored substance was identified as bis (4-methyl-2-nitrosophenolato) copper (II) by isolating it from the reaction mixture of 2-chloromercrui-4-methylphenol (an intermediate of the conventional Millon reaction of p-cresol), hydrogen nitrite and cupric ion. Millon-positive substances in urine were successfully determined by the present method by pretreating the sample with mercuric acetate.
