Abstract

The results of plasma-ammonium determinations by an ion-exchange method and by a microdiffusion method were compared on the same specimens with each other and with ammonium determinations carried out on the corresponding whole-blood specimens by the microdiffusion method. The plasma-ammonium levels of whole-blood specimens were higher than those of the corresponding plasma specimens, but the difference was not constant. Recoveries of added NH₄ from plasma by the microdiffusion method ranged from 65 to 144%. Recoveries of NH₄ from the same specimens by the ion-exchange method ranged from 93 to 96%. Of the two, the ion-exchange method was the only one of value.