Frequency-Tuned Contactless Conductivity Detector

The performance of high-frequency electrophoretic separation is necessarily connected with the use of capillaries with small inner diameter, which enfails the need to use a lower-frequency excitation signal for contactless conductivity detection ((CD)-D-4) than that used to date. In this way, the difficult-to-interpret minimum is eliminated from the (CD)-D-4 calibration curve and simultaneously maximum detection sensitivity is attained. Setting of the working parameters of (CD)-D-4 is further connected with the need to use a variable exeitation frequency, whose final value has to be optimised according to specific conductivity of background electrolytes and inner diameter of the separation capillary.