The colorimetric estimation of plasma amino nitrogen with DNFB.

A simple procedure for the estimation of plasmaamino nitrogen basedon the reaction of amino groupswith 2,4-dinitrofluorobenzene (DNFB) and subsequentmeasurement of the dinitrophenyl (DNP) amino derivatives at 420 m is presented. Elevated concentrations of bilirubin, hemoglobin, and the major nonprotein and nonamino acid nitrogen components of plasma do not seriously interfere. The proposed procedure comparesfavorably with a correspondingninhydrin technic for plasmaamino nitrogen. The mean plasma amino nitrogen values and range for a group of adults (age 18-50 years) by the proposed method is 5.56 mg./100 ml. (3.6-7.0 mg./100 ml.) compared to 4.12 mg./100 ml. (3.6-5.2 mg./100 ml.) for a group of children (age 2-10 years). Values from a group of children with sickle cell anemia showed no significant variance with the normal population. Optimum conditions for quantitation of plasma amino nitrogen along with other procedural parameters are presented.