Amperometric Detection in Capillary Electrophoresis with an Etched Joint

A system for coupling amperometric detection with capillary electrophoresis (CE) is demonstrated. In CE amperometric detection, the separation and detection capillaries are usually coupled with a porous joint to isolate the detector from the high applied voltage when the capillary inner diameter is larger than 25 μm. In this report a simple method is suggested. The joint was prepared by etching the capillary wall with HF after the polyimide coating of the capillary had been removed. This etched joint can efficiently isolate the detector from the high applied voltage. The performance of the CE-amperometric detection with an etched joint was evaluated with hydroquinone. The successful separation and amperometric detection of catecholic compounds, diphenols, and phenol have been carried out by this system.