Effect of AC voltage frequency on the sensitivity of conductometric detection in microseparation techniques

Conductometric detectors employed in microseparation methods are designed to primarily match the separation criteria. Consequently, their geometry is seldom optimal from the point of view of conductometry. An unsuitable detection cell geometry is manifested in the dependence of the conductometric cell constant on the frequency of the AC signal applied to the electrodes. Variations in the cell constant value cause changes in the measured signal even if the solution conductivity is constant. By varying the frequency of the AC signal it is thus possible to find an optimal frequency at which the highest detection sensitivity is attained. The optimum frequency depends both on the cell geometry and on the conductivity of the mobile phase solution.