Optimal operating frequency range for resistance measurements of two-electrode conductivity cells

The paper presents the results of studies of the impedance components of a secondary conductivity cell with platinum electrodes in the frequency range from 100 Hz to 300 kHz at low and medium values of the electrolytic conductivity (EC) of the liquid. Analysis of the frequency dependences of the real part and the tangent of the impedance phase angle shows that the frequency dependences of these parameters exhibit specific frequencies that make it possible to investigate the parameters of the polarization impedance and the bulk impedance separately from each other without the presence of a galvanic contact to them. The use of these specific frequencies makes it possible to determine the optimal operating frequency range for obtaining a minimum frequency error in measuring the real part of the resistance of a conductivity cell. Experimental verification of the existence of these frequencies and their calculability over the EC range makes it possible to conclude that the equivalent electrical circuit of a conductivity cell is described by a three-element equivalent circuit.