Integrated electrophoresis chips/amperometric detection with sputtered gold working electrodes

An on-chip electrochemical detector for micromachined capillary electrophoresis (CE) systems, based on sputtering a gold working electrode directly onto the capillary outlet, is described. The new on-chip detector preparation requires no microfabrication or alignment procedures nor a decoupling mechanism. The attractive performance of the integrated electrophoresis chips/amperometric detection was demonstrated for the anodic detection of neurotransmitters. The response for dopamine was linear from 20 to 200 mu M, with a LOD of 1.0 mu M and a sensitivity of 52 pA/mu M. Such intimate coupling of capillary electrophoresis chips and electrochemical detection facilitates the realization of complete integrated microanalytical devices.