毛细管的交流阻抗特性研究

Alternative Current Impedance Characteristics of Capillary

采用交流阻抗法研究了电容耦合非接触电导检测池毛细管的阻抗特性,分别考察了电极连接方式和毛细管内径对检测池阻抗的影响。实验表明:高频时,除去毛细管外层保护层会使检测池的阻抗减小,有助于检测器灵敏度的提高;采用铜箔作电极能够有效地消除电极与毛细管壁之间的空隙,使得检测池在低频时阻抗减小。随着毛细管内径的变大,阻抗依次减小。通过Zview软件拟合,提出的简单的拟合等效电路为R(RC)CPE。

The impedance characteristics of capacitively coupled contactless conductivity detection （C4D） cell in capillary electrophoresis was examined for different cell parameters by alternative current impedance（ACImp）technique. The effect of the electrodes material and the radius of the capillary on the impedance behavior of C4D cell were studied. As a result, the cell impedance decreased in the high frequency region without polyimide-coated on the capillary. The impedance increases with the increase of gap between the electrodes, which shows that tightly coupling of the electrodes to the outer wall of the capillary is needed. The impedance decreased with the increase of the radius of the capillary. The principle of axial contactless conductometric detector can effectively be explained by the simplest possible equivalent circuitry consisting of a capacitor, resistor, a second resister and the Warburg impedance.