Determination of phenylalanine in serum by a modified fluorimetric method in the diagnosis of phenylketonuria.

The paper describes the authors' experiences with the determination of serum phenylalanine by Hill's modification of the McCaman-Robins fluorimetric method for the determination of serum phenylalanine by automatic amino acid analysers. The method was modified by use of the dipeptide glycyl-leucine, which is 3 times cheaper to produce than leucyl-alanine, the dipeptide originally used. The above method is satisfactory for determining the serum phenylalanine level in normal clinical practice with the normally available, manually operated apparatuses.