Electrokinetic Methods for Preparative Electrophoresis on a Chip

This thesis describes research on preparative capillary electrophoresis on a chip. Capillary electrophoresis on a chip has one important drawback: the amount of an analyte obtained from a single run is very limited. Consequently, post-separation processing of the separated sample is challenging. Therefore methods for efficient, post-separation sample manipulation and handling are required. Such techniques should provide a way for pooling of separated identical components in order to provide sufficient amount of a sample for further off-chip, lab-scale processing. Alternatively, a method for continuous electrophoretic sample fractionation can be employed. In this project, the aim was the development of microfluidic electrokinetic-only strategies for microchip preparative CE. Particularly, the techniques for single fraction manipulation in complex channel networks were researched and methods that allow for fully automated control of such procedures were proposed. These techniques were later applied to develop a micropreparative CE chip device that was able to separate complex samples and pool identical fractions with no user interaction. Furthermore, an approach for continuously-operating zone electrophoresis was introduced and investigated. This new method, called continuous-flow zone electrophoresis (CFZE) separates analytes solely by electrophoresis and electro-osmosis. Unlike free-flow electrophoresis devices, no mechanical pumping is required. A preparative mode of CFZE, named synchronized, continuous-flow zone electrophoresis (SCFZE) was also investigated. This method allows for rapid and highly selective sample fractionation.