Conductivity Detection on Microchips

Conductivity detection as a versatile detection technique for chip-based electrophoretic separation methods is described and the basic principles are discussed. The necessary electronic equipment and technologies to implement the detection electrodes on a microchip are presented. A difference between contact and contactless detection is made and the resulting advantages and problems are shown. Different analytical applications are listed and discussed that show the basic applicability of conductivity detection in capillary electrophoresis and in isotachophoresis, which may serve as a guideline for more specific developments in the future. Central to all applications is the choice of the buffer system. It determines not only the separation capability but also puts limits on the achievable dynamic detection range.