The conductivity of the column effluent is continuosly measured and the appearance of the analyte in the cell is indicated by a change in conductivity.

Usually this is a very low volume flow-through capillary equipped with two electrodes and variations in conductivity of the mobile phase due to the eluted sample components are continuously recorded. Response is linear with concentration over a wide range,   quantitation of the output signal is possible with suitable preliminary calibration. Best use is made of this detector in isocratic analysis since solvent gradients will cause a proportional shift in the baseline.

Such detectors have been used most successfully in ion-exchange chromatography of anions and cation but generally, they have found only limited popular acceptance.