Estimation of alpha-amino nitrogen in plasma and urine by the colorimetric ninhydrin reaction

Abstract

Methods are described for the estimation of plasma and urine alpha-amino nitrogen by the colorimetric ninhydrin reaction; in the method for urine, both ammonia and urea are separated by a rapid ion-exchange resin procedure. Two methods of estimation are given; one has the advantage of great simplicity, but involves the use of cyanide; in the other, cyanide is eliminated. Normal values are reported; they correspond well with those obtained by the gasometric ninhydrin method.