New method for microdetermination of blood ammonia by use of cation exchange resin.

Abstract A micromethod for the determination of whole blood ammonia is described based on the cation exchange principle in which sodium and potassium ions are exchanged instantaneously for ammonium. The measurement of ammonia occurs after elution and reaction with Nessler's solution. The method offers the advantages of a storage form of the resin which can be held indefinitely, always ready for use. In addition, the procedure eliminates the sources of ammonia due to artifact present in methods currently in use and requires only 2 ml. of blood and 0.5 Gm. of resin. A number of samples may be collected at the bedside and can be held indefinitely after adsorption and washing is accomplished; elution and analysis may be completed when desired. Figures for the blood ammonium concentration in normal subjects and patients with nonhepatic as well as hepatic disease experiencing fluctuating states of consciousness are given.