Determination of Equivalent Circuit Parameters of a Contactless Conductive Detector in Capillary Electrophoresis by an Impedance Analysis Method

摘要

The equivalent circuit parameters of a capacitively coupled contactless conductive detector (C D) weremeasured by an impedance analysis method. The change in the equivalent circuit parameters was4 explained by an electrical line distribution model. It was shown that the total impedance of a C Dunder capillary electrophoresis conditions is composed mainly of the impedance from the wallcapacitor (CW). The value of CW is much less than that predicted from a cylinder capacitor model.With increasing solution conductivity in the capillary, the value of CW increases. As the electrodelength increases, Cw increases and attains to a plateau value. The effective electrode length is obviouslyless than its geometrical length. As the operating frequency increases, the value of Cw reduces4 dramatically. The response of a C D is due to the changes in both of Cw and solution resistance.