Determination of blood serum potassium by an improved sodium cobaltinitrite method

Abstract

The low accuracy of many methods of estimating serum K based on the Na cobaltinitrite procedure of Kramer and Tisdall is due mainly to 3 factors: the dilution of the serum with water, which can lead to as much as 20% of the K remaining unprecipitated owing to the solubility of K Na cabaltinitrite; allowing insufficient time for the precipitation of K; and dissolving some of the precipitate during washing. Modification of these and other factors has given a convenient method of improved accuracy. The results of replicate detns. agree closely, their standard deviation not exceeding 1% of their mean value, and the recovery of added K is satisfactory.