The Assay of Mixtures of Sodium-24 and Potassium-42 in Clinical Tracer Studies; with Particular Reference to the Measurement of Exchangeable Sodium and Potassium

Abstract

1. Combinations of different counting systems have been investigated for their efficiency in assaying mixtures of 24Na and 42K. The advantages of a combination of thin and thick walled liquid G.M. counter tubes of the Veall pattern are described. Physical methods are unreliable when only a small proportion of the counts is derived from one isotope. 2. The separation of potassium by precipitation with sodium tetraphenylboron is described. Methods dependent on chemical separation are reliable even when 42K makes only a small contribution to the counting rate of a mixture. 3. The application of these methods to the simultaneous measurement of exchangeable sodium and potassium is discussed and a rapid method for carrying out these measurements is described.