毛细管电泳多脉冲溶出安培检测方法的研究

The Application of Multi-Pulse Stripping Amperometric Detection to Capillary Electrophoresis

将用于电化学检测的三电极与驱动电泳分离的电化学系统的接地电极在毛细管出口处的外面作适当的布置 ,可最大程度地减少高压电场对安培检测的干扰。多阶脉冲溶出安培检测方式提高了电流检测灵敏度 ,并可在一定程度上通过不同的溶出电位鉴别分离组分。将该方法应用于铜、锌、铅、铊、镉等离子的毛细管电泳分离 ,得到了较满意的结果。

There are some drawbacks in amperometric detection in capillary electrophoresis since there is influence of high voltage from electrophoretic instrument. Three electrodes of electrochemical detection system and electrochemical system of capillary electrophoresis are separately placed in capillary outlet buffer reservoir, which can lead to a reduction in the influence of high voltage in the great degree. A carbon fiber with diameter of 7 μm is used as working electrode, and placed just at the separation capillary outlet. The multi pulse stripping amperometric detection has 1.1 s deposition step and several stripping steps with 0.02 s, which can increase the detection amperometric current and identify the species of each separated component in some classes by different pulse stripping potentials. This detection technique was applied in the separation of Cu, Zn, Pb, Tl and Cd of 25 mg/L by the capillary electrophoresis, and separation efficiency is over 60 thousands theoretical plates. The limit of the multi pulse stripping amperometry detection was 0.10 μg/L for cadmium by using water plug field amplified injection.