Cole–Cole Parameter Characterization of Urea and Potassium for Improving Dialysis Treatment Assessment

In this letter, we investigate the characteristics of the dielectric properties of urea and ions such as potassium and sodium, which are the principal molecules studied during dialysis treatment. The method involves measuring the electrical properties of varying concentrations of the constituent solutions over a broad frequency range and estimating the associated Cole-Cole parameters. We utilized concentrations above those expected in vivo to achieve a more accurate characterization. In these studies, we found that the conductivity was essentially constant with respect to urea concentration but had a strong, nearly linear correlation with potassium. In addition, the alpha factor had a distinct, monotonically varying relationship for both urea and potassium with significantly different initial slopes. Utilizing these two curves, simple inversion algorithms are possible to compute the solute concentrations given the Cole-Cole parameters. This concentration monitoring technique would be performed directly on the dialysate eliminating contamination from blood, which could substantially obscure the data. We expect that, using the Maxwell-Fricke mixture law, we will be able to compute the constituent concentrations even in the presence of trace amounts of competing molecules.