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Gradient Elution Moving Boundary Electrophoresis (GEMBE) for High-Throughput Multiplexed Microfluidic Devices



Jonathan G. Shackman, Matt S. Munson, David J. Ross


A novel method for performing electrophoretic separations is described - Gradient Elution Moving Boundary Electrophoresis (GEMBE). The technique utilizes the electrophoretic migration of chemical species in combination with variable hydrodynamic bulk counter-flow of the solution through a separation capillary or microfluidic channel. Continuous sample introduction is used, eliminating the need for a sample injection mechanism. Only analytes with an electrophoretic velocity greater than the counter-flow velocity enter the separation channel. The counter-flow velocity is varied over time so that each analyte is brought into the separation column at different times, allowing for high resolution separations in very short channels. The new variable of bulk flow acceleration affords a new selectivity parameter to electrophoresis analogous to gradient elution compositions in chromatography. Because it does not require extra channels or access ports to form an injection zone and because separations can be performed in very short channels, GEMBE separations can be implemented in much smaller areas on a microfluidic chip as compared to conventional capillary electrophoresis. Demonstrations of GEMBE separations of small dye molecules, amino acids, DNA, and immunoassay products are presented. A low-cost polymeric eight-channel multiplexed microfluidic device was fabricated to demonstrate the reduced area requirements of GEMBE; the device was less than one square inch in area and required only n+1 fluidic access ports per n analyses. The device was also used to generate a calibration curve for ahomogeneous insulin immunoassay using each of the eight channels as a calibration point.
Analytical Chemistry


capillary electrophoresis, DNA, immunoassay, multiplex separations


Shackman, J. , Munson, M. and Ross, D. (2007), Gradient Elution Moving Boundary Electrophoresis (GEMBE) for High-Throughput Multiplexed Microfluidic Devices, Analytical Chemistry (Accessed April 18, 2024)
Created January 15, 2007, Updated February 17, 2017