Chapter 3: Principles and Strategies for Microchip Electrophoresis with Amperometric Detection

Microchip electrophoresis (ME) is a powerful separation method utilizing micron and submicron planar channels and allowing many applications where traditional capillary electrophoresis cannot be employed. Amperometry is an ideal detection method in ME due to its high sensitivity, ease of integrating electrodes into the microfluidic platform, simplicity of instrumentation, ease of miniaturization, and comparatively low cost. In addition, many biologically and environmentally important compounds are electroactive. However, both ME and amperometry involve application of an electric field, and these voltages must be isolated from one another to obtain maximum sensitivity and limits of detection. In this chapter, theories of both amperometric detection and ME are discussed. Theoretical and experimental aspects of the effect of interaction of separation voltage on the working electrode are presented. Three commonly employed electrode configurations for amperometric detection in ME are described. Discussions of the determination of signal and noise, and calculation of signal-to-noise ratio for ME–EC analyses, are included. Selection of appropriate electrode materials and configuration to obtain the best selectivity, analyte identification, and overall performance for specific analyte classes is described. Lastly, applications of ME with amperometric detection are highlighted in areas of biological, environmental, and food sciences.