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Performance Bottlenecks in Dynamic Field Gradient Focusing

Jeffrey M. Burke and Cornelius F. Ivory. Chemical Engineering, Washington State University, Pullman, WA 99163

Dynamic Field Gradient Focusing (DFGF) is an equilibrium gradient method, of which isoelectric focusing (IEF) is a member, that utilizes an electric field gradient generated by a computer-controlled electrode array to simultaneously separate and concentrate charged analytes. Dynamic control of the electrode array allows for manipulation of the electric field profile during the course of an experiment to increase peak resolution, migrate analytes to off-take ports or to systematically elute individual species. Unlike IEF, which separates based on isoelectric points (pI), DFGF does not require that the analytes be amphoteric but instead have differences in their individual electrophoretic mobilities. As a result, separation can occur at pHs far removed from the pIs, thus negating problems associated with decreased solubilities. Though DFGF has shown significant potential as a powerful analytical technique for the emerging “omics” fields, full acceptance has be hindered by several performance bottlenecks that have led to reproducibility issues, diminished concentration factors and lower than expected resolution and peak capacity. This paper addresses the possible sources to these problems along with proposed solutions.