Technique for the measurement of high purity water

Abstract From the Canadian patent

Improved accuracy in solution conductivity or resistivity measurement uses a center-sampling technique in which an AC drive is applied to a conductivity cell - and the conductivity cell voltage is sampled during a predetermined time interval in the center of a half cycle drive waveform. The effects of cell capacitance and, particularly the electrode-solution capacitive are, compensated by periodically sampling during a second time interval which is different from the first interval. Based upon the difference between the sampled voltages in the first and second intervals a, correction to the measured conductivity or resistivity is made to compensate for capacitance induced errors.